C1 Forth

Computer One Forth was released by Computer One Ltd, to provide an implementation of the high-level language Forth.

Forth was developed originally by Charles Moore in the 1960s to help him control large telescopes in his observatory and is noted for its speed and reverse Polish notation (eg. to get the sum of 3 and 2 you enter: 3 2 +

Forth is also noted for files being developed as a series of pages - basically, you keep defining functions until you reach the simplest level of function - making the language probably the most modular programming language.

C1 Forth was developed with the help of Steve Pelc, an experienced Forth programmer who previously implemented the language for computers such as the Apple II.

Listed features:

• FORTH-83 SYSTEM
• Forth Screen Editor
• 100-page Manual
• Produce stand-alone programs
• QL Graphics and sound extensions
• Example FORTH programs
• FORTH macro-assembler
• Multitasking extensions with many powerful features

During 2011 a Forth programmer identified some bugs in version 2.0 of C1 Forth and has released a patch to fix these issues.

The most serious bug affected all the words that implemented some kind of integer division ( / mod /mod ... etc), where division of negative numbers yielded a quotient of 0 (rather than have been -1).

The other two bugs rectified by this patch are:

"NOT" in Forth83 is defined as the "bitwise negation" of a 16 bits number, whereas in this release, it behaved like "0=", a boolean test.

"D+!" is a word that which produced garbage.

The program was originally written by MicroProcessor Engineering Ltd on a Sage CP/M68k computer and is a port of Laboratory Microsystems 68k Forth.

Title: Computer One Forth
Language: 68000 Machine Code
Author: MicroProcessor Engineering Ltd
Publisher: Computer One Ltd
Year of Publication: 1985
Platforms Suitable for: All Sinclair QLs and emulators
Commercial Status: Commercial
Price as at January 1985: £39.95
Reviews: Unknown
Sources Available from: n/a
Latest Version available from: RWAP Software website