eris2010

TBuserMan.txt (54216B)

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              I T T Y   B I T T Y   C O M P U T E R S
 
                       TINY BASIC User Manual
 
 
 
 
 
 
 
       Congratulations!  You have received the first of what we hope
 is a long line of low cost software for hobby computers.  We are
 operating on a low margin basis, and hope to make a profit on
 volume.  Please help us to stay in business by respecting the
 Copyright notices on the software and documentation.
       If you are in a hurry to try TINY BASIC, Appendix C will tell
 you how to get on the air.  Then come back and read the rest of this
 manual --- most of it is useful information.
 
       The TINY BASIC interpreter program has been extensively tested
 for errors ("bugs"), but it would be foolish to claim of any program
 that it is guaranteed bug-free.  This program does come with a
 "Limited Warranty" in that any errors discovered will be corrected in
 the first 90 days.  Catastrophic bugs will be corrected by
 automatically mailing out corrected versions to all direct mail
 customers and local dealers.  Minor bugs will be corrected by
 request.  In any case this warranty is limited to replacement of the
 Program Tape and/or documentation, and no liability for consequential
 damages is implied.
       If you think you have found a bug, make a listing of the
 program that demonstrates the bug, together with the run input and
 output.  Indicate on the listing what you think is wrong and what
 version number you are running and your serial number (on the tape
 leader).  Mail this to:
 
       ITTY BITTY COMPUTERS
       P.0. Box 6539
       San Jose, CA   95150
 
 We will try to be responsive to your needs.
 
 
 ----------
 (C) Copyright 1976 by Tom Pittman.  All rights reserved.
 
 "Itty Bitty" is a Trademark of the ITTY BITTY COMPUTERS Company.
 
 
                                   1
 
       TINY BASIC was conceived by the dragons at the People's
 Computer Company (PCC), a non-profit corporation in Menlo Park CA.
 and its implementation defined by Dennis Allison and others in the
 PCC newspaper and an offshoot newsletter.  The implementation of this
 program follows the philosophy defined there.  The reader is referred
 to PCC v.4 Nos 1-3 for a discussion of the inner workings of this
 software.
       In keeping with the "small is good" philosophy, TINY BASIC
 employs the two level interpreter approach (with its consequent speed
 cost) so that the whole system occupies only 2K of program memory
 (exclusive of user program; some versions are slightly larger).
 With 1K of additional RAM small but useful user programs (50 lines or
 less) may be accommodated. A system with 4K of RAM can contain the
 interpreter and about 100 lines of user program.
 
       TINY BASIC is offered in several versions for each processor.
 One is designed to be used with an arbitrary operating system, and
 executes out of low memory (e.g. 0100-08FF for the 6800). The other
 versions are configured for unusual memory requirements of particular
 operating systems. All are "clean" programs, in that they will
 execute properly from protected memory (such as PROM). Direct
 addressing is used for interpreter variables as much as possible, so
 memory Page 00 is largely dedicated. In all cases the user programs
 are placed at the end of that part of lower memory used by TINY, and
 they may occupy all the remaining contiguous memory. Appendix D is a
 a summary of the important low-memory addresses.
       TINY BASIC is designed to be I/O independent, with all input
 and output funneled through three jumps placed near the beginning of
 the program.  In the non-standard versions these are preset for the
 particular operating system I/O, so the discussion to follow is
 primarily concerned with the standard versions.  For this
 discussion, it is assumed that the interpreter begins at hex address
 0100, though the remarks may be applied to other versions with an
 appropriate offset.
       Location 0106 is a JMP to a subroutine to read one ASCII
 character from the console/terminal.  Location 0109 is a JMP to a
 subroutine to type or display one ASCII character on the
 console/terminal.  In both cases the character is in the A
 accumulator, but the subroutine need not preserve the contents of the
 other registers.  It is assumed that the character input routine will
 simultaneously display each character as it is input; if this is not
 the case, the JMP instruction in location 0106 may be converted to a
 JSR, so that each character input flows through the output subroutine
 (which in this case must preserve A) before being fed to TINY.
 Users with terminals using Baudot or some other non-ASCII code should
 perform the character conversion in the Input and Output subroutines.
 If your console is a CRT and/or you have no need to output or
 display extra pad characters with each Carriage Return and Linefeed,
 you may intercept these in the output routine to bypass their
 display.  Each input prompt by TINY is followed by an "X-ON"
 character (ASCII DC1) with the sign bit set to 1 (all other
 characters except rubout are output with the sign bit set to 0) so
 these are also readily detected and deleted from the output stream.
 Appendix C shows how to perform these tests.
       A third subroutine provided by you is optional, and gives TINY
 
 
                                   2
 
 a means to test for the BREAK condition in your system.  Appendix C
 shows how this subroutine may be implemented for different types of
 I/O devices.  If you choose to omit this subroutine, TINY will assume
 that a BREAK condition never happens; to include it, simply replace
 locations 010C-010E with a JMP to your subroutine, which returns with
 the break condition recorded in the Carry flag (1 = BREAK, 0 = no
 BREAK).  The Break condition is used to interrupt program execution,
 or to prematurely terminate a LIST operation.  Tiny responds to the
 Break condition any time in the LIST, or just before examining the
 next statement in program execution.  If a LIST statement included
 within a program is aborted by the Break condition, the Break
 condition must be held over to the next statement fetch (or repeated)
 to stop program execution also.
       All input to Tiny is buffered in a 72 character line,
 terminated by a Carriage Return ("CR").  Excess characters are
 ignored, as signaled by ringing the console/terminal bell.  When the
 CR is typed in, Tiny will echo it with a Linefeed, then proceed to
 process the information in the line.  If a typing error occurs during
 the input of either a program line or data for an INPUT statement,
 the erroneous characters may be deleted by "backspacing" over them
 and retyping. If the entire line is in error, it may be canceled
 (and thus ignored) by typing the "Cancel" key.  The Backspace code is
 located near the beginning of the program (location 010F), and is
 set by default to "left-arrow" or ASCII Underline (shift-O on your
 Teletype).  To change this to the ASCII Standard Backspace code (or
 anything else you choose), the contents of location 010F may be
 changed to the desired code.  Similarly the Cancel code is located at
 memory address 0110, and is set by default to the ASCII Cancel code
 (Control-X).  Four characters which may not be used for line edits
 (Backspace or Cancel) are DC3 (hex 13), LF (0A), NUL (00), and DEL
 (FF).  These codes are trapped by the TINY BASIC input routines
 before line edits are tested.
       When Tiny ends a line (either input or output), it types a CR,
 two pad characters, a Linefeed, and one more pad character.  The pad
 character used is defined by the sign bit in location 0111, and is
 set by default to the "Rubout" or Delete code (hex FF; Location 0111
 Bit 7 = 1) to minimize synchronization loss for bit-banger I/O
 routines.  The pad character may be changed to a Null (hex 00) by
 setting the sign of location 0111 to 0.  The remainder of this byte
 defines the number of Pad characters between the CR and linefeed.
 More than two pad characters may be required if large user programs
 are to be loaded from tape (see comments on Tape Mode, below).
       TINY BASIC has a provision for suppressing output (in
 particular line prompts) when using paper tape for loading a program
 or inputting data.  This is activated by the occurrence of a Linefeed
 in the input stream (note that the user normally has no cause to type
 a Linefeed since it is echoed in response to each CR), and disables
 all output (including program output) until the tape mode is
 deactivated.  This is especially useful in half-duplex I/O systems
 such as that supported by Mikbug, since any output would interfere
 with incoming tape data.  The tape mode is turned off by the
 occurrence of an X-OFF character (ASCII DC3, or Control-S) in the
 input, by the termination of an executing program due to an error, or
 after the execution of any statement or command which leaves Tiny in
 the command mode.  The tape mode may be disabled completely by
 replacing the contents of memory location 0112 with a 00.
 
                                   3
 
       Memory location 0113 is of interest to those 6800 users with
 extensive operating systems.  Normally Tiny reserves 32 bytes of
 stack space for use by the interpreter and I/O routines (including
 interrupts).  Up to half of these may be used by Tiny in normal
 operation, leaving not more than 16 bytes on the stack for I/O.  If
 your system allows nested interrupts or uses much more than ten or
 twelve stack bytes for any purpose, additional space must be
 allocated on the stack.  Location 0113 contains the reserve stack
 space parameter used by Tiny, and is normally set to 32 (hex 20).  If
 your system requires more reserve, this value should be augmented
 accordingly before attempting to run the interpreter.
       All of these memory locations are summarized in Appendix D.
 Note that there are no Input or Output instructions or interrupt
 disables in the interpreter itself; aside from the routines provided
 for your convenience (which you may connect or disconnect), your
 system has complete control over the I/O and interrupt structure of
 the TINY BASIC environment.
 
       TINY BASIC is designed to use all of the memory available to it
 for user programs.  This is done by scanning all the memory from the
 beginning of the user program space (e.g. 0900 for the standard 6800
 version) for the end of contiguous memory.  This then becomes the
 user program space, and any previous contents may be obliterated.
 If it is desired to preserve some part of this memory for machine
 language subroutines or I/O routines, it will be necessary to omit
 the memory scan initialization.  This is facilitated in TINY BASIC by
 the definition of two starting addresses.  Location 0100 (or the
 beginning of the interpreter) is the "Cold Start" entry point, and
 makes no assumptions about the contents of memory, except that it is
 available.  Location 0103 is the "Warm Start" entry point, and
 assumes that the upper and lower bounds of the user program memory
 have been defined, and that the program space is correctly
 formatted.  The Warm Start does not destroy any TINY BASIC programs
 in the program space, so it may be used to recover from catastrophic
 failures.  The lower bound is stored in locations 0020-0021 and the
 upper bound is in locations 0022-0023.  When using the Warm Start to
 preserve memory, you should be sure these locations contain the
 bounds of the user space.  Also when using the Warm Start instead of
 the Cold Start, the first command typed into TINY should be "CLEAR"
 to properly format the program space.
 
 
 STATEMENTS
 
       TINY BASIC is a subset of Dartmouth BASIC, with a few
 extensions to adapt it to the microcomputer environment.  Appendix B
 contains a BNF definition of the language; the discussion here is
 intended to enable you to use it.  When TINY issues a line prompt (a
 colon on the left margin) you may type in a statement with or without
 a line number.  If the line number is included, the entire line is
 inserted into the user program space in line number sequence, without
 further analysis.  Any previously existing line with the same line
 number is deleted or replaced by the new line.  If the new line
 consists of a line number only, it is considered a deletion, and
 nothing is inserted.  Blanks are not significant to TINY, so blanks
 
 
                                   4
 
 imbedded in the line number are ignored; however, after the first
 non-blank, non-numeric character in the line, all blanks are
 preserved in memory.
       The following are valid lines with line numbers!
 
       123 PRINT "HELLO"
       456    G O T O 1 2 3
       7 8 9 PRINT "THIS IS LINE # 789"
       123
       32767 PRINT "THIS IS THE LARGEST LINE #"
       1PRINT"THIS, IS THE SMALLEST LINE #"
       10000 TINY BASIC DOES NOT CHECK
       10001 FOR EXECUTABLE STATEMENTS ON INSERTION.
 
       0 Is not a valid line number.
 
       If the input line does not begin with a line number it is
 executed directly, and must consist of one of the following statement
 types:
 
       LET             GOTO            REM
       IF...THEN       GOSUB           CLEAR
       INPUT           RETURN          LIST
       PRINT           END             RUN
 
       These statement types are discussed in more detail in the pages
 to follow.
       Note that all twelve statement types may be used in either the
 Direct Execution mode (without a line number) or in a program
 sequence (with a line number).  Two of the statements (INPUT and RUN)
 behave slightly differently in these two operating modes, but
 otherwise each statement works the same in Direct Execution as within
 a program.  Obviously there is not much point in including such
 statements as RUN or CLEAR in a program, but they are valid.
 Similarly, a GOSUB statement executed directly, though valid, is
 likely to result in an error stop when the corresponding RETURN
 statement is executed.
 
 
 EXPRESSIONS
 
       Many of these statement types involve the use of EXPRESSIONS.
 An Expression is the combination of one or more NUMBERS or VARIABLES,
 joined by OPERATORS, and possibly grouped by Parentheses.  There are
 four Operators:
       +   addition
       -   subtraction
       *   multiplication
       /   division
 These are hierarchical, so that in an expression without parentheses,
 multiplication and division are performed before addition and
 subtraction.  Similarly, sub-expressions within parentheses are
 evaluated first.  Otherwise evaluation proceeds from left to right.
 Unary operators (+ and -) are allowed in front of an expression to
 denote its sign.
 
 
                                   5
 
       A Number is any sequence of decimal digits (0, 1, 2, ... 9),
 denoting the decimal number so represented.  Blanks have no
 significance and may be imbedded within the number for readability if
 desired, but commas are not allowed.  All numbers are evaluated as
 16-bit signed numbers, so numbers with five or more digits are
 truncated modulo 65536, with values greater than 32767 being
 considered negative.  The following are some valid numbers (note
 that the last two are equivalent to the first two in TINY):
 
       0
       100
       10 000
       1 2 3 4
       32767
       65536
       65 636
 
       A Variable is any Capital letter (A, B, ... Z). This variable
 is assigned a fixed location in memory (two bytes, the address of
 which is twice the ASCII representation of the variable name).  It
 may assume any value in the range, -32768 to +32767, as assigned to
 it by a LET or INPUT statement.
       The following are some examples of valid expressions:
       A
       123
       1+2-3
       B-14*C
       (A+B)/(C+D)
       -128/(-32768+(I*1))
       (((((Q)))))
 
       All expressions are evaluated as integers modulo 65536.  Thus
 an expression such as
       N / P * P
 may not evaluate to the same value as (N), and in fact this may be
 put to use to determine if a variable is an exact multiple of some
 number.  TINY BASIC also makes no attempt to discover arithmetic
 overflow conditions, except in the case of an attempt to divide by
 zero (which results in an error stop).  Thus all of the following
 expressions evaluate to the same value:
       -4096
       15*4096
       32768/8
       30720+30720
 
       TINY BASIC allows two intrinsic functions.  These are:
       RND (range)
       USR (address,Xreg,Areg)
 Either of these functions may be used anywhere an (expression) is
 appropriate.
 
 
 
 
 
 
 
                                   6
 
 FUNCTIONS
 
 
       RND (range)
 
       This function has as its value, a positive pseudo-random number
 between zero and range-1, inclusive.  If the range argument is zero
 an error stop results.
 
 
 
       USR (address)
       USR (address,Xreg)
       USR (address,Xreg,Areg)
 
       This function is actually a machine-language subroutine call to
 the address in the first argument.  If the second argument is
 included the index registers contain that value on entry to the
 subroutine, with the most significant part in X.  If the third
 argument is included, the accumulators contain that value on entry to
 the subroutine, with the least significant part in A.  On exit, the
 value in the Accumulators (for the 6800; A and Y for the 6502)
 becomes the value of the function, with the least significant part in
 A.  All three arguments are evaluated as normal expressions.
       It should be noted that machine language subroutine addresses
 are 16-bit Binary numbers.  TINY BASIC evaluates all expressions to
 16-bit binary numbers, so any valid expression may be used to define
 a subroutine address.  However, most addresses are expressed in
 hexadecimal whereas TINY BASIC only accepts numerical constants in
 decimal.  Thus to jump to a subroutine at hex address 40AF, you must
 code USR(16559). Hex address FFB5 is similarly 65461 in decimal,
 though the equivalent (-75) may be easier to use.
       For your convenience two subroutines have been included in the
 TINY BASIC interpreter to access memory.  If S contains the address
 of the beginning of the TINY BASIC interpreter (256 for standard
 6800, 512 for standard 6502, etc.), then location S+20 (hex 0114) is
 the entry point of a subroutine to read one byte from the memory
 address in the index register, and location S+24 (hex 0118) is the
 entry point of a subroutine to store one byte into memory.
       Appendix E gives examples of the USR function.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
                                   7
 
 STATEMENT TYPES
 
 
       PRINT print-list
       PR print-list
 
       This statement prints on the console/terminal the values of the
 expressions and/or the contents of the strings in the print-list.
 The print-list has the general form,
       item,item...    or      item;item...
 The items may be expressions or alphanumeric strings enclosed in
 quotation marks (e.g. "STRING").  Expressions are evaluated and
 printed as signed numbers; strings are printed as they occur in the
 PRINT statement.  When the items are separated by commas the printed
 values are justified in columns of 8 characters wide; when semicolons
 are used there is no separation between the printed items. Thus,
       PRINT 1,2,3
 prints as
       1       2       3
 and
       PRINT 1;2;3
 prints as
       123
 Commas and semicolons, strings and expressions may be mixed in one
 PRINT statement at will.
       If a PRINT statement ends with a comma or semicolon TINY BASIC
 will not terminate the output line so that several PRINT statements
 may print on the same output line, or an output message may be
 printed on the same line as an input request (see INPUT).  When the
 PRINT statement does not end with a comma or semicolon the output is
 terminated with a carriage return and linefeed (with their associated
 pad characters).  To aid in preparing data tapes for input to other
 programs, a colon at the end of a print-list will output an "X-OFF"
 control character just before the Carriage Return.
 
       Although the PRINT statement generates the output immediately
 while scanning the statement line, output lines are limited to 125
 characters, with excess suppressed.
 
       While the Break key will not interrupt a PRINT statement in
 progress, the Break condition will take effect at the end of the
 current PRINT statement.
 
       The following are some examples of valid PRINT statements:
       PRINT "A=";A,"B+C=";B+C
       PR                        (one blank line)
       PRI                       (prints the value of I)
       PRINT 1,","Q*P;",",R/42:
 
 
 
 
 
 
 
 
 
                                   8
 
       INPUT input-list
 
       This statement checks to see if the current input line is
 exhausted.  If it is, a question mark is prompted with an X-ON
 control character, and a new line is read in.  Then or otherwise, the
 input line is scanned for an expression which is evaluated.  The
 value thus derived is stored in the first variable in the input-list.
 If there are more variables in the input-list the process is
 repeated.  In an executing program, several values may be input on a
 single request by separating them with commas.  If these values are
 not used up in the current INPUT statement they are saved for
 subsequent INPUT statements.  The question mark is prompted only when
 a new line of input values is required.  Note that each line of input
 values must be terminated by a carriage return.  Since expressions
 may be used as input values, any letter in the input line will be
 interpreted as the value of that variable.  Thus if a program sets
 the value of A to 1, B to 2, and C to 3, and the following statement
 occurs during execution:
       INPUT X,Y,Z
 and the user types in
       A,C,B
 the values entered into X, Y, and Z will be 1, 3, and 2,
 respectively, just as if the numbers had been typed in.  Note also
 that blanks on the input line are ignored by TINY, and the commas are
 required only for separation in cases of ambiguity.  In the example
 above
       ACB
 could have been typed in with the same results.  However an input,
 line typed in as
       +1  -3  +6   0
 will be interpreted by TINY as a single value (=58) without commas
 for separators.  There is one anomaly in the expression input
 capability: if in response to this INPUT, the user types,
       RND+3
 TINY will stop on a bad function syntax error (the RND function must
 be of the form, RND(x)); but if the user types,
       RN,D+3
 the values in the variables R, N, and the expression (D+3) will be
 input.  This is because in the expression evaluator the intrinsic
 function names are recognized before variables, as long as they are
 correctly spelled.
 
       Due to the way TINY BASIC buffers its input lines, the INPUT
 statement cannot be directly executed for more than one variable at a
 time, and if the following statement is typed in without a line
 number,
       INPUT A,B,C
 the value of B will be copied to A, and only one value (for C) will
 be requested from the console/terminal.  Similarly, the statement,
       INPUT X,1,Y,2,Z,3
 will execute directly (loading X, Y, and Z with the values 1, 2, and
 3), requesting no input, but with a line number in a program this
 statement will produce an error stop after requesting one value.
 
       If the number of expressions in the input line does not match
 the number of variables in the INPUT statement, the excess input is
 
                                   9
 
 saved for the next INPUT statement, or another prompt is issued for
 more data. The user should note that misalignment in these
 circumstances may result in incorrect program execution (the wrong
 data to the wrong variables). If this is suspected, data entry may be
 typed in one value at a time to observe its synchronization with
 PRINT statements in the program.
       There is no defined escape from an input request, but if an
 invalid expression is typed (such as a period or a pair of commas) an
 invalid expression error stop will occur.
 
       Because Tiny Basic does not allow arrays, about the only way to
 process large volumes of data is through paper tape files.  Each
 input request prompt consists of a question mark followed by an X-ON
 (ASCII DC1) control character to turn on an automatic paper tape
 reader on the Teletype (if it is ready).  A paper tape may be
 prepared in advance with data separated by commas, and an X-OFF
 (ASCII DC3 or Control-S) control character preceding the CR (a
 Teletype will generally read at least one more character after the
 X-OFF).  In this way the tape will feed one line at a time, as
 requested by the succession of INPUT statements.  This tape may also
 be prepared from a previous program output (see the PRINT
 statement).
 
 
 
 
 
       LET var = expression
       var = expression
 
       This statement assigns the value of the expression to the
 variable (var).  The long form of this statement (i.e. with the
 keyword LET) executes slightly faster than the short form.  The
 following are valid LET statements:
 
       LET A = B+C
       I = 0
       LET Q = RND (RND(33)+5)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
                                   10
 
       GOTO expression
 
       The GOTO statement permits changes in the sequence of program
 execution.  Normally programs are executed in the numerical sequence
 of the program line numbers, but the next statement to be executed
 after a GOTO has the line number derived by the evaluation of the
 expression in the GOTO statement.  Note that this permits you to
 compute the line number of the next statement on the basis of program
 parameters during program execution.  An error stop occurs if the
 evaluation of the expression results in a number for which there is
 no line.  If a GOTO statement is executed directly, it has the same
 effect as if it were the first line of a program, and the RUN
 statement were typed in, that is, program execution begins from that
 line number, even though it may not be the first in the program.
 Thus a program may be continued where it left off after correcting
 the cause of an error stop.  The following are valid GOTO
 statements:
       GOTO 100
       GO TO 200+I*10
       G 0 T 0 X
 
 
 
 
 
 
       GOSUB expression
 
       The GOSUB statement is like the GOTO statement, except that TINY
 remembers the line number of the GOSUB statement, so that the next
 occurrence of a RETURN statement will result in execution proceeding
 from the statement following the GOSUB.  Subroutines called by GOSUB
 statements may be nested to any depth, limited only by the amount of
 user program memory remaining.  Note that a GOSUB directly executed
 may result in an error stop at the corresponding RETURN.  The
 following are some examples of valid GOSUB statements:
       GOSUB 100
       GO SUB 200+I*10
 
 
 
 
 
 
 RETURN
 
       The RETURN statement transfers execution control to the line
 following the most recent unRETURNed GOSUB.  If there is no matching
 GOSUB an error stop occurs.
 
 
 
 
 
 
 
 
                                   11
 
       IF expression rel expression THEN statement
       IF expression rel expression statement
 
       The IF statement compares two expressions according to one of
 six relational operators.  If the relationship is True, the statement
 is executed; if False, the associated statement is skipped.  The six
 relational operators are:
       =               equality
       <               less than
       >               greater than
       <=              less or equal (not greater)
       >=              greater or equal (not less)
       <>, ><          not equal (greater or less)
 
       The statement may be any valid TINY BASIC statement (including
 another IF statement).  The following are valid IF statements:
       IF I>25 THEN PRINT "ERROR"
       IF N/P*P=N GOTO 100
       IF 1=2 Then this is nonsense
       IF RND (100) > 50 THEN IF I <> J INPUT Q,R
 
 
 
 
 
 
      END
 
      The END statement must be the last executable statement in a
 program.  Failure to include an END statement will result in an error
 stop after the last line of the program is executed.  The END
 statement may be used to terminate a program at any time, and there
 may be as many END statements in a program as needed.  The END
 statement also clears out any saved GOSUB line numbers remaining, and
 may be used for that purpose in the direct execution mode.
 
 
 
 
 
 
       REM comments
 
       The REM statement permits comments to be interspersed in the
 program.  Its execution has no effect on program operation, except
 for the time taken.
 
 
 
 
 
 
 
 
 
 
 
                                   12
 
       CLEAR
 
       The CLEAR statement formats the user program space, deleting
 any previous programs.  If included in a program (i.e. with a line
 number) the program becomes suicidal when the statement is executed,
 although no error results.  If the Warm Start is used to initialize
 the interpreter, this must be the first command given.
 
 
 
       RUN
       RUN,expression-list
 
       The RUN statement is used to begin program execution at the
 first (lowest) line number.  If the RUN statement is directly
 executed, it may be followed by a comma, followed by values to be
 input when the program executes an INPUT statement.
       If the RUN statement is included in a program with a line
 number, its execution works like a GO TO first statement of the
 program.
 
 
 
       LIST
       LIST expression
       LIST expression,expression
 
       The LIST statement causes part or all of the user program to be
 listed.  If no parameters are given, the whole program is listed.  A
 single expression parameter in evaluated to a line number which, if
 it exists, is listed.  If both expression parameters are given, all
 of the lines with line numbers between the two values (inclusive) are
 listed.  If the last expression in the LIST statement evaluates to a
 number for which there is no line, the next line above that number
 which does exist (if any) is listed as the last line.  Zero is not a
 valid line number, and an error stop will occur if one of the
 expressions evaluates to zero.  A LIST statement may be included as
 part of the program, which may be used for printing large text
 strings such as instructions to the operator.  A listing may be
 terminated by the Break key.
       If the terminal punch (or cassette recorder) is turned on for a
 LIST operation, the tape may be saved to reload the program into TINY
 at a later time.
       The following are valid LIST statements:
       LIST
       LIST 75+25            (lists line 100)
       LIST 100,200
       LIST 500,400          (lists nothing)
 
 
 
 
 
 
 
 
 
                                   13
 
                     A P P E N D I X   A
 
                    ERROR MESSAGE SUMMARY
 
 
 0     Break during execution
 8     Memory overflow; line not inserted
 9     Line number 0 not allowed
 13    RUN with no program in memory
 18    LET is missing a variable name
 20    LET is missing an =
 23    Improper syntax in LET
 25    LET is not followed by END
 34    Improper syntax in GOTO
 37    No line to GO TO
 39    Misspelled GOTO
 40,41 Misspelled GOSUB
 46    GOSUB subroutine does not exist
 59    PRINT not followed by END
 62    Missing close quote in PRINT string
 73    Colon in PRINT is not at end of statement
 75    PRINT not followed by END
 95    IF not followed by END
 104   INPUT syntax bad - expects variable name
 123   INPUT syntax bad - expects comma
 124   INPUT not followed by END
 132   RETURN syntax bad
 133   RETURN has no matching GOSUB
 134   GOSUB not followed by END
 139   END syntax bad
 154   Can't LIST line number 0
 164   LIST syntax error - expects comma
 183   REM not followed by END
 184   Missing statement type keyword
 186   Misspelled statement type keyword
 188   Memory overflow: too many GOSUB's ...
 211      ... or expression too complex
 224   Divide by 0
 226   Memory overflow
 232   Expression too complex ...
 233      ... using RND ...
 234      ... in direct evaluation;
 253      ... simplify the expression
 259   RND (0) not allowed
 266   Expression too complex ...
 267      ... for RND
 275   USR expects "(" before arguments
 284   USR expects ")" after arguments
 287   Expression too complex ...
 288      ... for USR
 290   Expression too complex
 293   Syntax error in expression - expects value
 296   Syntax error - expects ")"
 298   Memory overflow (in USR)
 303   Expression too complex (in USR)
 
 
                                   14
 
 304   Memory overflow (in function evaluation)
 306   Syntax error - expects "(" for function arguments
 330   IF syntax error - expects relation operator
 
       Other error message numbers may possibly occur if the
 interpreter is malfunctioning.  If this happens, check the program in
 memory, or reload it, and try again.
 
       Error number 184 may also occur if TINY BASIC is incorrectly
 interfaced to the keyboard input routines.  A memory dump of the
 input line buffer may disclose this kind of irregularity.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
                                   15
 
                      A P P E N D I X   B
 
                FORMAL DEFINITION OF TINY BASIC
 
 
 line ::= number statement CR
          statement CR
 statement ::= PRINT printlist
               PR printlist
               INPUT varlist
               LET var = expression
               var = expression
               GOTO expression
               GOSUB expression
               RETURN
               IF expression relop expression THEN statement
               IF expression relop expression statement
               REM commentstring
               CLEAR
               RUN
               RUN exprlist
               LIST
               LIST exprlist
 printlist ::=
               printitem
               printitem :
               printitem separator printlist
 printitem ::= expression
               "characterstring"
 varlist ::= var
             var , varlist
 exprlist ::= expression
              expression , exprlist
 expression ::= unsignedexpr
                + unsignedexpr
                - unsignedexpr
 unsignedexpr ::= term
                  term + unsignedexpr
                  term - unsignedexpr
 term ::= factor
          factor * term
          factor / term
 factor ::= var
            number
            ( expression )
            function
 function ::= RND ( expression )
              USR ( exprlist )
 number ::= digit
            digit number
 separator ::= , ! ;
 var ::= A ! B ! ... ! Y ! Z
 digit ::= 0 ! 1 2 ! ... ! 9
 relop ::= < ! > ! = ! <= ! >= ! <> ! ><
 
 
 
                                   16
 
 
                          A P P E N D I X   C
 
                       IMPLEMENTING I/O ROUTINES
 
 COSMAC
 
 COSMAC TINY occupies the same space as 6800 TINY -- 0100-08FF.
 Similarly, the general parameters occupy 0020-00B7, as defined in
 the manual.  However, COSMAC TINY also uses locations 0011-001F to
 contain copies of interpreter parameters and other run-time data; do
 not attempt to use these locations while running TINY.
 
 Like all Itty Bitty Computer software, COSMAC TINY contains no I/O
 instructions (nor references to Q or EF1-4), no interrupt enables or
 disables, and no references to an operating system.  The three jumps
 (LBR instructions) at 0106, 0109, and 010C provide all necessary
 I/O, as defined in the manual.  If you are using UT3 or UT4, you may
 insert the following LBR instructions, which jump to the necessary
 interface routines:
 
                         ..  LINKS TO UT3/4
         0106 C0076F             LBR UTIN
         0109 C00776             LBR UTOUT
         010C C00766             LBR UTBRK
 
 If you are not using the RCA monitor, you must write your own I/O
 routines.  For this the standard subroutine call and return linkages
 are used, except that D is preserved through calls and returns by
 storing it in RF.1.  Registers R2-RB and RD contain essential
 interpreter data, and if the I/O routines make any use of any of
 them they should be saved and restored.  Note however, that R2-R6
 are defined in the customary way and may be used to nest subroutine
 calls if needed.  R0, R1, RC, RE and RF are available for use by the
 I/O routines, as is memory under R2.  Both the call and return
 linkages modify X and the I/O data character is passed in the
 accumulator ("D", not RD).
 
 After connecting TINY to the I/O routines, start the processor at
 0100 (the Cold Start).  Do not attempt to use the Warm Start without
 entering the Cold Start at least once to set up memory from
 0011-0023.  Any register may be serving as program counter when
 entering either the Cold Start or the Warm Start.
 
 The USR function works the same way as described in the manual,
 except that the second argument in the call is loaded into R8, and
 the third argument is loaded into RA with the least significant
 byte also in the Accumulator.  On return RA.1 and the accumulator
 contain the function value (RA.0 is ignored).  The machine language
 subroutine must exit by a SEP R5 instruction.  USR machine language
 subroutines may use R0, R1, R8, RA, RC-RF, so long as these do not
 conflict with I/O routine assignments.  TINY BASIC makes no internal
 use of R0, R1, RC, or RE.
 
 RCA Corporation funded the development of COSMAC TINY BASIC, and it
 is by RCA's permission that it is made available.
 
                                   17
      If you do not have access to a monitor in ROM with ASCII I/O
 built in, you will have to write your own I/O routines.  Most likely
 you have something connected to a parallel port for the keyboard
 input; output may be some parallel port also, or you may want to 
 use the 1861 video display for a gross dot-matrix kind of text 
 display.  For the moment, let's assume you have parallel ports, 
 Port C (N=1100) for input, and port 4 (N=0100) for output.  Assume 
 also that EF4 controls both input and output.  This is the situation 
 you would have if you took an ordinary ELF and used the hex input 
 and display with the single "input" button to step through the 
 characters.  You need for this configuration, two routines, which 
 might look something like this:
      0106 C0 00E0    LBR KEYIN
      0109 C0 00E7    LBR DISPL
      ...
      00E0 3FE0 KEYIN BN4 *
      00E2 E2         SEX 2
      00E3 6C         INP 4
      00E4 37E4       B4  *
      00E6 68         LSKP
      00E7 3FE7 DISPL BN4 *
      00E9 E2         SEX 2
      00EA 73         STXD
      00EB 52         STR 2
      00EC 64         OUT 4
      00ED 37ED       B4  *
      00EF D5         SEP 5
      Of course if you have a keyboard on Port F you will change 
 the INP instruction to match; if the keyboard pulls EF3 down, then 
 you must change the first pair of BN4/B4 instructions to BN3/B3
 instructions and change the LSKP to a NOP (C4 or E2).  If your 
 input comes from some device that already displayed the character 
 typed, then change the LSKP to a Return (D5).
      Similarly, if the output is to a different port you must 
 change the OUT instruction to fit it, and the second pair of BN4/B4 
 instructions to match the control line being used. Notice that 
 the LSKP instruction is only there to prevent your waiting on the 
 EF4 line twice for each keyin, and should be removed (changed to 
 a NOP) as soon as you connect up real input and output ports.
      Many 1802 systems come equipped with a video output using 
 the 1861 chip.  If you have this, you should get a copy of the 
 February and April 1979 issues of KILOBAUD MICROCOMPUTING (formerly 
 just KILOBAUD). I have a two-part article published in these two 
 issues which explains how to put text on the 1861 graphics display, 
 with particular emphasis on how to connect it to TINY BASIC.
      So far I have not mentioned the Break test. If you leave 
 that part unchanged, Tiny will work just fine, but you cannot stop 
 a listing or a program that is getting too long.  After you get 
 your keyboard and display connected up and working, you may want 
 to use EF4 (or some other flag) as a Break input. It is possible 
 to use the same flag for Break as for "input ready", if you want 
 Tiny to stop executing when you press a key on your keyboard (this 
 does not affect the INPUT instruction, which is obviously waiting 
 for that keyin). This code will do that:
      010C C000F0     LBR BRKT
      ...
      00F0 FC00  BRKT ADI 0
      00F2 3FF6       BN4 EXIT
      00F4 FF00       SMI 0
      00F6 D5    EXIT SEP R5
      Notice that the only function of this routine is to set the 
 Carry (DF) when EF4 is true (low) and clear it otherwise.
 
                                   18
 
 KIM
 
       The Teletype I/O routines in the MOS Technology KIM system may
 be used for the character input and output requirements of TINY BASIC
 6502.  The following break routine is included in Tiny to test the
 serial data line at 1740;  Since TINY BASIC 6502 does not use the
 lower part of memory page 01, the break test routine is ORG'ed to
 execute in that space:
 
             ;  BREAK TEST FOR KIM
 0100 AD4017 KIMBT LDA KTTY      LOOK AT TTY
 0103 18           CLC           C=O IF IDLE
 0104 300E         BMI KIMX      IDLE
 0106 AD4017       LDA KTTY      WAIT FOR END
 0109 10FB         BPL *-3
 010B 200E01 KLDY  JSR *+3
 010E A9FF         LDA #255      DELAY 2 RUBOUT TIMES
 0110 20A01E       JSR OUTCH
 0113 38           SEC           C=1 IF BREAK
 0114 60     KIMX  RTS
 
       To run TINY BASIC 6502 load the paper tape into your Teletype
 reader, type "L", and turn on the reader.  Then key in the following
 Jumps:
 
             ;  JUMPS TO KIM
 0206 4C5A1E     JMP GETCH       CHARACTER INPUT
 0209 4CA01E     JMP OUTCH       CHARACTER OUTPUT
 020C 4C0001     JMP KIMBT       BREAK TEST
 
       It is recommended that you save a copy of memory on tape
 (0100-0114 and 0200-0AFF) before going any further.  Or you may
 prefer to save it on audio cassette.  Set up the starting address for
 Tiny at 0200, and type "G".
       Because of the awkwardness of putting memory in the 4K gap left
 in the KIM-1 system, an alternate version is available which executes
 out of 2000-28FF.  For this version the Cold Start is at 2000 and
 other addresses are at 200x instead of 020x (cf. 010x in Appendix D).
 
 
 JOLT or TIM
 
       JOLT systems may not always have memory loaded in the space
 from 0200 on up, so a special version has been prepared in which the
 interpreter resides in the space 1000-18FF.  This is the only
 difference between the JOLT version and the KIM version, so if your
 JOLT or TIM system has contiguous memory from Page 00 you may prefer
 to use the KIM version to gain the extra memory space.  Since the
 serial data in the JOLT/TIM systems is not the same as KIM, a special
 break test routine has also been provided for those systems:
 
             ; JOLT BREAK TEST
 0115 A901   JOLBT LDA #1        LOOK AT TTY
 0117 2C026E       BIT JTTY
 011A 18           CLC           C=0 IF IDLE
 
 
                                   19
 
 011B F00E         BEQ JOLTX     IDLE
 011D 2C026E       BIT JTTY      WAIT FOR END
 0120 D0FB         BNE *-3
 0122 202501       JSR *+3       DELAY TWO CH TIMES
 0125 A9FF         LDA #255
 0127 20C672       JSR WRT
 012A 38           SEC           C=1 = BREAK
 012B 60     JOLTX RTS
 
       To run, load the paper tape into your Teletype reader and type
 "LH".  Then key in the following Jumps:
 
             ;  JUMPS TO JOLT/TIM
 1006 4CE972     JMP RDT         CHARACTER INPUT
 1009 4CC672     JMP WRT         CHARACTER OUTPUT
 100C 4C1501     JMP JOLBT       BREAK TEST
 
       As with other versions, the Cold start is the beginning of the
 program (1000).
 
 
 
 MIKBUG
 
       Systems that use MIKBUG (TM Motorola) for console I/O may use
 the I/O routines in MIKBUG.  The following break routine is provided
 in Tiny to test the PIA at 8004:
 
         *  BREAK TEST FOR MIKBUG
 
 B68004  BREAK   LDA A PIAA      LOOK AT PIA
 0C              CLC             C=0 IF NONE
 2B0D            BMI EXIT
 B68004          LDA A PIAA
 2AFB            BPL *-3         WAIT FOR END
 8D00            BSR *+2
 86FF            LDA A #$FF      DELAY ONE
 BD0109          JSR TYPE        CHARACTER TIME
 0D              SEC             C=1 IF BREAK
 39      EXIT    RTS
 
       To run, load the paper tape into your Teletype reader and type
 "L".  Then key in the following Jumps:
 
             *  JUMPS TO MIKBUG
                 ORG $0106
 0106 7EE1AC     JMP $E1AC       CHARACTER INPUT
 0109 7EE1D1     JMP $E1D1       CHARACTER OUTPUT
 010C 7E08FD     JMP $08FD       BREAK TEST
 
       It is recommended that you save a copy of memory on tape
 (0100-08FF) before going any further.  Set the starting address in
 A048-A049 to 0100 and type "G". For your convenience the Cold Start
 entry leaves the Warm start entry set up in the Mikbug stack, so that
 after a reset a simple "G" command will result in a Warm start and
 preserve the user programs.
 
                                   20
 
 OTHER
 
       For standard systems (and for special systems with I/O other
 than that provided), subroutines must be supplied by the user to
 interface TINY to the operator.  For ACIA input or output the
 following routines may be used, or they may serve as examples for
 your coding (6800 opcodes are shown).  They should be assembled for
 your ACIA address, and in some memory location which is not
 contiguous with the TINY BASIC user program memory (which may be
 destroyed by the Cold Start).  If nothing else is available,
 locations 00D8-00FF are not used by Tiny and may be used for this
 purpose.
 
        *
        *  ACIA I/O
        *
 B6XXXX BREAK   LDA A ACIA
 47             ASR A           CHECK FOR TYPEIN
 2406           BCC BRX         NO, NOT BREAK
 B6XXXY         LDA A ACIA+1    GET IT
 2601           BNE BRX         NOT NULL IS BREAK
 0C             CLC             IGNORE NULLS
 39     BRX     RTS
 B6XXXX INPUT   LDA A ACIA
 47             ASR A
 24FA           BCC INPUT       WAIT FOR A CHARACTER
 B6XXXY         LDA A ACIA+1    GET IT
 36     OUTPUT  PSH A           SAVE CHARACTER
 B6XXXX         LDA A ACIA
 8402           AND A #2        WAIT FOR READY
 27F9           BEQ OUTPUT+1
 32             PUL A
 B7XXXY         STA A ACIA+1    OUTPUT CHARACTER
 39             RTS
 
       Note that this routine will accept any non-null character
 typein as a break.  Alternatively we could look at the Framing Error
 status, but if a character has been input this status will not show
 up until that character is read in, rendering it ineffective in some
 cases.  Nulls are excepted as break characters since one or more of
 them may follow the carriage return in an input tape, and still be
 pending.  Note that for this to work properly, the pad character
 defined in location 0111 should be set to NULL (hex 00).
 
       The 6800 "R" version of TINY BASIC includes these routines in
 the code, as shown here.  Locations 08FA-08FC contain a JMP to the
 break test at the beginning of this block.  You should alter the ACIA
 addresses to suit your system before using the subroutines.
 
 
 
 
 
 
 
 
 
                                   21
 
 CRT OR TVT
 
       If a TV Typewriter is used for I/O it may be desirable to
 remove excess control characters from the output stream.  All
 controls except Carriage Return may be removed by the following
 instructions at the beginning of the output subroutine (6800 opcodes
 shown):
 
 39             RTS
 810A   OUTPUT  CMP A #0A
 2FFB           BLE OUTPUT-1
 
 Only nulls, Rubouts, X-ON and X-OFF may be deleted by changing the
 CMP to a TST A.  Nulls may be passed through by also changing the BLE
 to a BMI.
 
       Some TV Typewriters do not scroll up when the cursor reaches
 the bottom of the screen, but rather wrap the cursor around to the
 top of the screen, writing over the previously displayed data.  With
 this kind of display it is essential that the I/O routines (or the
 hardware) clear to the end of the line whenever a CR-LF is output,
 so that previous data does not interfere with the new.  If your I/O
 routines are fixed in ROM, some sort of preprocessor may be required
 to recognize output CR's and convert them to the appropriate sequence
 of control functions.  It may also be necessary to trap input CR's
 (suppressing their echo) since Tiny generally responds with both
 another CR and a linefeed.
 
       Some users prefer to concatenate all output into one "line" of
 print, using the terminal comma or semicolon to suppress the line
 breaks.  Since TINY was designed to limit line lengths to less than
 128 characters, if this sort of concatenation is attempted it will
 appear that TINY has quit running.  To eliminate the print
 suppression the most significant two bits of the print control byte
 (location 00BF in most versions) may be cleared to zero periodically
 with the USR function or in the output driver routine.  The least
 significant three bits of this same byte are used for the "comma
 spacing" in the PRINT statement, and should be left unaltered.
 
 
 
 CASSETTE I/O
 
       Officially, TINY only speaks to one peripheral--the console.
 However a certain amount of file storage may be simulated by
 attaching these peripherals (such as cassette systems) to the
 character input and output routines.  If the same electrical and
 software interface is used this is very easy.  Otherwise the I/O
 drivers will require special routines to recognize control characters
 in the input and output data for setting internal switches which
 select one of several peripherals.  The USR function may also be
 used either to directly call I/O routines or to alter switches in
 memory.
 
 
 
 
                                   22
 
 
 
 
 
                          A P P E N D I X   D
 
                            LOW MEMORY MAP
 
 
 LOCATION        SIGNIFICANCE
 --------        ------------
 
 0000-000F       Not used by any version of TINY
 0011-001F       COSMAC version temporaries
 0020-0021       Lowest address of user program space
 0022-0023       Highest address of program space
 0024-0025       Program end + stack reserve
 0026-0027       Top of GOSUB stack
 0028-002F       Interpreter parameters
 0030-007F       Input line buffer & Computation stack
 0080-0081       Random Number Generator workspace
 0082-0083       Variable "A"
 0084-0085       Variable "B"
 ...             ...
 00B4-00B5       Variable "Z"
 00B6-00C7       Interpreter temporaries
 00B8            Start of User program (PROTO)
 00C8-00D7       Sphere parameters (not 0020-002F)
 00D8-00FF       Unused by standard version
 
 0100            Cold Start entry point (6800)
 0103            Warm Start entry point
 0106-0108       JMP (or JSR) to character input
 0109-010B       JMP to character output
 010C-010E       JMP to Break test
 010F            Backspace code
 0110            Line Cancel code
 0111            Pad character
 0112            Tape Mode Enable flag (hex 80 = enabled)
 0113            Spare stack size
 0114            Subroutine to read one Byte
                   from RAM to A (address in X)
 0118            Subroutine to store A into RAM
                   at address in X
 
 0900            Beginning of User program (6800)
 
 Note that some of these addresses apply to the standard 6800 version.
 For other versions addresses above 0100 should be read as addresses
 above their respective starting address.
 
 
 
 
 
 
 
                                   23
 
                          A P P E N D I X   E
 
                          AN EXAMPLE PROGRAM
 
 
 10 REM DISPLAY 64 RANDOM NUMBERS < 100 ON 8 LINES
 20 LET I=0
 30 PRINT RND (100),
 40 LET I=I+1
 50 IF I/8*8=I THEN PRINT
 60 IF I<64 THEN GOTO 30
 70 END
 
 
 100 REM PRINT HEX MEMORY DUMP
 109 REM INITIALIZE
 110 A=-10
 120 B=-11
 130 C=-12
 140 D=-13
 150 E=-14
 160 F=-15
 170 X = -1
 175 O = 0
 180 LET S = 256
 190 REMARK: S IS BEGINNING OF TINY (IN DECIMAL)
 200 REM GET (HEX) ADDRESSES
 210 PRINT "DUMP: L,U";
 215 REM INPUT STARTING ADDRESS IN HEX
 220 GOSUB 500
 230 L=N
 235 REM INPUT ENDING ADDRESS IN HEX
 240 GOSUB 500
 250 U=N
 275 REM TYPE OUT ADDRESS
 280 GOSUB 450
 290 REM GET MEMORY BYTE
 300 LET N = USR (S+20,L)
 305 REM CONVERT IT TO HEX
 310 LET M = N/16
 320 LET N = N-M*16
 330 PRINT " ";
 335 REM PRINT IT
 340 GOSUB 400+M+M
 350 GOSUB 400+N+N
 355 REM END?
 360 IF L=U GO TO 390
 365 L=L+1
 370 IF L/16*16 = L GOTO 280
 375 REM DO 16 BYTES PER LINE
 380 GO TO 300
 390 PRINT
 395 END
 399 PRINT ONE HEX DIGIT
 400 PRINT O;
 
 
                                   24
 
 401 RETURN
 402 PRINT 1;
 403 RETURN
 404 PRINT 2;
 405 RETURN
 406 PRINT 3;
 407 RETURN
 408 PRINT 4;
 409 RETURN
 410 PRINT 5;
 411 RETURN
 412 PRINT 6;
 413 RETURN
 414 PRINT 7;
 415 RETURN
 416 PRINT 8;
 417 RETURN
 418 PRINT 9;
 419 RETURN
 420 PRINT "A";
 421 RETURN
 422 PRINT "B";
 423 RETURN
 424 PRINT "C";
 425 RETURN
 426 PRINT "D";
 427 RETURN
 428 PRINT "E";
 429 RETURN
 430 PRINT "F";
 431 RETURN
 440 REM PRINT HEX ADDRESS
 450 PRINT
 455 REM CONVERT IT TO HEX
 460 N = L/4096
 470 IF L<0 N=(L-32768)/4096+8
 480 GOSUB 400+N+N
 483 LET N=(L-N*4096)
 486 GOSUB 400+N/256*2
 490 GOSUB 400+(N-N/256*256)/16*2
 495 GOTO 400+(N-N/16*16)*2
 496 GOTO=GOSUB,RETURN
 500 REM INPUT HEX NUMBER
 501 REM FORMAT IS NNNNX
 502 REM WHERE "N" IS ANY HEX DIGIT
 505 N=0
 509 REM INPUT LETTER OR STRING OF DIGITS
 510 INPUT R
 520 IF R=X RETURN
 525 REM CHECK FOR ERROR
 530 IF R>9999 THEN PRINT "BAD HEX ADDRESS
 531 REM NOTE ERROR STOP ON LINE 530 (ON PURPOSE!)
 535 REM CONVERT INPUT DECIMAL DIGITS TO HEX
 540 IF R>999 THEN N=N*16
 545 IF R>99 THEN N=N*16
 550 IF R>9 THEN N=N*16
 
                                   25
 
 555 IF R>0 THEN R=R+R/1000*1536+R/100*96+R/10*6
 559 REM PICK UP NON-DECIMAL DIGIT LETTERS
 560 IF R<0 THEN LET R=-R
 565 REM ADD NEW DIGIT TO PREVIOUS NUMBER
 570 LET N=N*16+R
 580 GOTO 510
 590 NOTE: DON'T NEED END HERE
 
 
 1000 TO RUN RANDOM NUMBER PROGRAM, TYPE "RUN"
 1010 IT WILL TYPE 8 LINES THEN STOP.
 1020 TO RUN HEX DUMP PROGRAM TYPE "GOTO 100"
 1030 IT WILL ASK FOR INPUT, TYPE 2 HEX ADDRESSES
 1040 EACH TERMINATED BY THE LETTER X,
 1050 AND SEPARATED BY A COMMA
 1055 (TYPE ALL ZEROS AS LETTER OH).
 1060 THE PROGRAM WILL DUMP MEMORY BETWEEN
 1070 THOSE TWO ADDRESSES, INCLUSIVE.
 1080 EXAMPLE:
 1090 :GOTO 100
 1100 DUMP: L,U? AO3EX,AO46X
 1110 A03E EE FF
 1120 A040 00 11 22 33 44 55 66
 1130 IF THE RANDOM NUMBER PROGRAM
 1140 IS REMOVED, OR IF YOU TYPE IN
 1150 :1 GOTO 100
 1160 THEN YOU CAN GET THE SAME DUMP BY TYPING
 1170 :RUN,AO3EX,AO46X
 1180 .
 1190 NOTE THAT THIS PROGRAM DEMONSTRATES NEARLY
 1200 EVERY FEATURE AVAILABLE IN TINY BASIC.
 
 
 
 REMARK: TO FIND OUT HOW MUCH PROGRAM SPACE
 REM... YOU HAVE LEFT, TYPE:
 LET I=0
 1 LET I=I+2
 2 GOSUB 1
 RUN
 REMARK: AFTER A FEW SECONDS, THIS WILL STOP
 REM... WITH AN ERROR; THEN TYPE:
 END
 PRINT "THERE ARE ";I;" BYTES LEFT"
 
 
 REM: TO EXIT FROM TINY BASIC TO YOUR MONITOR/DEBUGGER,
 LET S=256
 REM (S AS IN LINE 180 ABOVE)
 LET B=0
 IF P=6800 THEN LET B=63
 REM: B IS SWI OR BRK INSTRUCTION
 LET A = USR (S+24,0,B) + USR (0)
 REM: THE FIRST CALL STORES A BREAK IN 0000
 REM... THE SECOND CALL JUMPS TO IT.
 
 
                                   26