This is a listing of Tiny BASIC Extended, by Dick Whipple and John Arnold. The listing (as presented here) originally appeared in SIGPLAN Notices, July 1976. The SIGPLAN article is a reprint of an article that appeared in the January 1976 issue of Dr. Dobb's Journal of Tiny BASIC Calisthenics & Orthodontia (the very first issue of Dr. Dobbs Journal.) A type-in of the binary was in the first issue, the source code appeared in the second issue.

The file tinybasic.oct is a recreation of the original split octal listing, and closely resembles how it appeared in the first issue of DDJ. This version of Tiny BASIC is written in 8080 machine code. The listing was hand-typed from a PDF scan of a bad photocopy, so there are very likely errors. However, I was able to load this into an 8080 emulator and enter some very simple programs. It is possible that this will work with an Altair 8800 (or an emulator.)

In order to bring up this version of Tiny BASIC, load the binary into memory at 1000H. In addition, you will need to specify several routines in low memory:

Address 0 of memory should initialize the stack pointer and jump to the Tiny BASIC entry point. I used the following code

    ADDR    INST   8080
    000000  061
    000001  377
    000002  000    LD SP, 00FFH
    000003  303
    000004  254
    000005  021    JP 11ACH

Address 030 (18H) should read an ASCII character from the input device into register A. If ESC is pressed, jump to the cold start routine. No registers should be modified except A.

Address 050 (28H) should output the ASCII character stored in register A. No registers should be modified.

Address 020 (10H) should output a CR followed by a LF. You can do whatever newline processing you'd like instead. Only register A may be modified.

In my Z80 simulator, I entered the cold start routine into memory, and implemented the other three routines as traps. I adopted a slightly different scheme for the JavaScript 8080 simulator included in this repository. In that version, I used I/O so that input from port 0 fetches a character, output to port 0 outputs a character, and output to port 1 outputs a newline.

Multiplication table

 10 FOR I = 1 TO 12
 20 FOR J = 1 TO 12
 30 PR I*J;
 40 NXT J
 50 PR
 60 NXT I
 70 END

Transcript of session with Tiny BASIC

 :NEW

 :10 FOR I = 1 TO 12
 :20 FOR J = 1 TO 12
 :30 PR I*J;
 :40 NXT J
 :50 PR
 :60 NXT I
 :70 END
 :LST

 00010 FOR I = 1 TO 12
 00020 FOR J = 1 TO 12
 00030 PR I*J;
 00040 NXT J
 00050 PR
 00060 NXT I
 00070 END
 :LST 20

 00020 FOR J = 1 TO 12
 :LST 20,40

 00020 FOR J = 1 TO 12
 00030 PR I*J;
 00040 NXT J
 :RUN

 1 2 3 4 5 6 7 8 9 10 11 12
 2 4 6 8 10 12 14 16 18 20 22 24
 3 6 9 12 15 18 21 24 27 30 33 36
 4 8 12 16 20 24 28 32 36 40 44 48
 5 10 15 20 25 30 35 40 45 50 55 60
 6 12 18 24 30 36 42 48 54 60 66 72
 7 14 21 28 35 42 49 56 63 70 77 84
 8 16 24 32 40 48 56 64 72 80 88 96
 9 18 27 36 45 54 63 72 81 90 99 108
 10 20 30 40 50 60 70 80 90 100 110 120
 11 22 33 44 55 66 77 88 99 110 121 132
 12 24 36 48 60 72 84 96 108 120 132 144

 :

In the js/ directory, there is a very primitive simulator of an Intel 8080 based computer running Tiny BASIC. You can run this in the browser by loading index.html. You can also access a live demo.

The Tiny BASIC prompt is the colon :. Before you enter a program, you must type NEW at the prompt. If you don't, entering a program line will cause Tiny BASIC to hang.

You'll notice several differences from other BASICs, most importantly

• Instead of PRINT or ? Tiny BASIC uses PR
• Instead of NEXT in a loop, Tiny BASIC uses NXT
• Instead of LIST to list a program, Tiny BASIC uses LST
• Instead of INPUT to prompt for input, Tiny BASIC uses IN
• Input is numeric. Complete by hitting SPACE (most BASIC dialects complete input by hitting RETURN/ENTER)
• Instead of : to put multiple statements on a single line, Tiny BASIC uses $
• Programs should be terminated with END
• Only 16 bit integers are supported
• Only one letter variable names are supported

Original specification by Dennis Allison

Original listing by Dick Whipple and John Arnold

JavaScript 8080 emulator by Alexander Demin's i8080-js

Transcribed from the original by Eric Scharff, March 2007

JavaScript 8080 simulator added by Eric Scharff, March 2025