Retrocomputing Basic Implementations

Here is a summary of a number of Basic implementations that I have come across and worked with as part of my retrocomputing hobby. Many of these were ported by me or others to different platforms from the ones they were originally written for (for example, single board computers based on the 6502, 6809, Z80, and 68000 microprocessors). These are all found on my github  account.

Name	Developer	Platform	Code size	Comments
Enhanced Basic (68000)	Lee Davison	68000	14K	Full-featured Basic for 68K platform
Tiny Basic for the 68000	Gordon Brandly	68000	4K	Derived from and similar to Palo Alto Tiny Basic.
Enhanced Basic (6502)	Lee Davison	6502	11K	Full-featured Basic for 6502 platform.
Microsoft Basic for 6502	Microsoft	Apple 2, Commodore, KIM-1, OSI, and others	8K	Basic used on several early 6502-based microcomputers.
Tiny Basic for 6502	Tom Pitman	6502	3K	Originally published in Dr. Dobbs Journal.
Apple 1 Basic	Steve Wozniak	6502 (Apple 1)	4K	Basic for the Apple 1, later expanded into Apple 2 Integer Basic.
BBC Basic 2 for Acorn Atom/BBC Computer	Roger Wilson (Acorn Computer)	6502-based Acorn Atom and BBC Computers	16K	Basic for the Acorn Atom and BBC Computers.
Tiny Basic for 6800	Tom Pitman	6800	2K	My version runs on the Heathkit ETA-3400.
Tiny Basic for 6809	Tom Pitman	6809	2K	6809 port of 6800 version.
TSC Micro BASIC PLUS	Technical Systems Consultants	6809	4K	Similar to Tiny Basic.
Sinclair ZX81 Basic	John Grant and Steve Vickers, Nine Tiles Networks and Sinclair Research	Sinclair ZX80/ZX81, Timex 1000	8K	Basic for the Sinclair ZX81 computer.

Building a 68000 Single Board Computer - Tiny Basic

Tiny BASIC is a dialect of the BASIC programming language that was originally written by Dennis Allison for early microcomputers including 6502 systems like the KIM-1. It could fit into as little as two or three kilobytes of memory. I earlier blogged about running the 6502 version on my Replica 1 computer.

Tiny Basic spawned a newsletter called Dr. Dobb's Journal of Tiny BASIC Calisthenics and Orthodontia, which evolved into the magazine Dr. Dobb's Journal. In 1985, the 100th issue of Dr. Dobb's Journal published an article by Gordon Brandly describing a Tiny Basic interpreter he had written for the Motorola 68000 microprocessor.

I came across this and thought I would try porting it to my TS2 computer. It turns out that no porting is needed, as it was designed to run on the Motorola MEX68KECB Educational Computer Board, which the TS2 is compatible with. I simply loaded the Motorola S record file and it came up on the console:

TUTOR  1.3 > GO 900
PHYSICAL ADDRESS=00000900

Gordo's MC68000 Tiny BASIC, v1.2

OK
>

The supported Basic keywords are BYE, CALL, FOR, GOSUB, GOTO, IF, INPUT, LET, LIST, LOAD, NEW, NEXT, PEEK, POKE, PRINT, READ, REM, RETURN, RUN, SAVE, STEP, STOP, AND TO. It is quite a limited version of Basic (it is only about 3K in size!), but some programs have been developed for or ported to it. One that comes with the Tiny Basic distribution is a version of the classic Star Trek game. Here is a transcript of a portion of a game:

> RUN
Do you want a difficult game?  (Y or N): N
Stardate 3200:  Your mission is to destroy 5 Klingons in 30 stardates.
There are 3 starbases.
Enterprise in Q-75 S-31
Captain: HELP
R=Report       S=SR. sensor   L=LR. sensor
G=Galaxy map   P=Phaser       T=Torpedo
W=Warp engine  * Please use one of these commands *
Captain: R
Status report:
Stardate      3200
Time Left     30
Condition     Green
Position      Q-75 S-31
Energy        4000
Torpedoes     10
Klingons left  5
Starbases     3
Captain: G
Enterprise in Q-75 S-31
Computer display of galaxy map

1:   0   0   0   0   0   0   0   0

2:   0   0   0   0   0   0   0   0

3:   0   0   0   0   0   0   0   0

4:   0   0   0   0   0   0   0   0

5:   0   0   0   0   0   0   0   0

6:   0   0   0   0   0   0   0   0

7:   0   0   0   0   0   0   0   0

8:   0   0   0   0   0   0   0   0
    ..  ..  ..  ..  ..  ..  ..  ..
     1   2   3   4   5   6   7   8

Captain: S
Enterprise in Q-75 S-31
Short range sensor
1 . . . . . . . .
2 . . . . . . . .
3 E . . . . . . .
4 . . . . . . . .
5 . . . . . . . .
6 . . . . . . . .
7 . . . . . . . .
8 . . . . . . . *
  1 2 3 4 5 6 7 8
Captain: L
Enterprise in Q-75 S-31
Long range sensor
   1   7   7
   1   1   1
 101   5   1
Captain: W
Captain: W
Warp engine
Sector distance: 10
Course (0-360): 180
Enterprise in Q-84 S-61
Klingon attack
218 units hit from Klingon at S-63
160 units hit from Klingon at S-51
143 units hit from Klingon at S-21
124 units hit from Klingon at S-12
3305 units of energy left.
Captain: S
Enterprise in Q-84 S-61
Short range sensor
1 . K . . . . . *
2 K . . . . . . .
3 . . . . . . . .
4 . . . . . . . .
5 K . . . . . . .
6 E . K . . . . .
7 . . . . . . . .
8 * . . . . . . .
  1 2 3 4 5 6 7 8
Captain: W
Warp engine
Sector distance: 1
Course (0-360): 0
**EMERGENCY STOP**
Spock: "To err is Human."
Enterprise in Q-84 S-61
Klingon attack
242 units hit from Klingon at S-63
172 units hit from Klingon at S-51
189 units hit from Klingon at S-21
 83 units hit from Klingon at S-12
2619 units of energy left.
Shield damaged, 4 stardates estimated for repair
Captain: S
Enterprise in Q-84 S-61
Short range sensor
1 . K . . . . . *
2 K . . . . . . .
3 . . . . . . . .
4 . . . . . . . .
5 K . . . . . . .
6 E . K . . . . .
7 . . . . . . . .
8 * . . . . . . .
  1 2 3 4 5 6 7 8
Captain: 

The article about Tiny Basic was also published in a book: Dr. Dobb's Toolbook of 68000 Programming. I'll have to see if I can find a copy of this.

Tiny Basic for the Replica 1

Tiny BASIC is a dialect of the BASIC programming language that was written by Dennis Allison for early microcomputers including 6502 systems like the KIM-1. It could fit into as little as 2 or 3 kilobytes of memory.

I came across this web page with a lot of information about this version by Tom Pittman.

It's a little more primitive than the Apple BASIC for the Apple 1, lacking even FOR NEXT loops. It's also quite slow because it is implemented using an interpreted language called (so it's an interpreter written in an interpreter written in machine language).

Tiny Basic spawned a newsletter called Dr. Dobb's Journal of Tiny BASIC Calisthenics and Orthodontia which evolved into the Dr. Dobb's Journal which is still published today.

Bill O'Neill disassembled a 6502 version of Tiny Basic, added comments, and got it working with generic 6502 systems using a serial ACIA for input and output. I ported it  to the Replica 1 in an evening, only having to make a few changes:

• modifications to assemble with the CC65 assembler
• modifying the input and output routines for the Replica 1
• making some memory map changes to run out of RAM by default

The picture below shows Tiny Basic on startup.

Tiny Basic Startup

And running some simple BASIC code:

Running Some BASIC Code

Many programs were written in Tiny Basic including some quite large adventure type games. Below is a screen shot of one such game:

An Adventure Game

So I now have one more BASIC to add to my collection of ports to the Replica 1 which now includes Apple BASIC, Applesoft Lite, Microsoft Basic (based on the Ohio Scientific version), Enhanced Basic, and Tiny Basic.