This page (revision-114) was last changed on 24-Feb-2023 14:10 by Andreas Tartz 

This page was created on 08-Mar-2010 20:15 by Carsten Strotmann

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Version Date Modified Size Author Changes ... Change note
114 24-Feb-2023 14:10 18 KB Andreas Tartz to previous
113 24-Feb-2023 13:11 18 KB Andreas Tartz to previous | to last
112 24-Feb-2023 13:09 18 KB Andreas Tartz to previous | to last
111 24-Feb-2023 13:06 17 KB Andreas Tartz to previous | to last
110 24-Feb-2023 12:57 17 KB Andreas Tartz to previous | to last
109 24-Feb-2023 12:53 17 KB Andreas Tartz to previous | to last
108 24-Feb-2023 12:38 17 KB Andreas Tartz to previous | to last
107 03-Feb-2023 15:21 17 KB Maury Markowitz to previous | to last
106 13-Dec-2021 16:05 17 KB Maury Markowitz to previous | to last
105 16-Sep-2021 13:46 17 KB Maury Markowitz to previous | to last
104 16-Sep-2021 13:30 17 KB Maury Markowitz to previous | to last general cleanup
103 29-Jul-2020 21:57 17 KB Peter Dell to previous | to last TURBO-BASIC XL ==> Turbo-BASIC XL
102 23-May-2020 05:03 17 KB Roland B. Wassenberg to previous | to last
101 01-May-2020 02:03 17 KB Roland B. Wassenberg to previous | to last

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Atari BASIC
Atari BASIC

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!!!Atari Basic
!!!Atari BASIC
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Atari BASIC was originally written by Shepardson Microsystems in late 1978 as part of a somewhat rushed effort to make a BASIC that would fit in an 8k ROM. The standard BASIC of the era, Microsoft's "8k basic", was actually around 9k, and the most common versions were about 11k. In spite of their best efforts, Atari programmers failed to pare it to 8k, and hired Shepardson to do it for them.
Atari originally licensed the 6502-assembler code for Microsoft BASIC, which was about 9k in size. The Atari design limited cartridges to 8k, and the Atari programmers struggled to cut the MS code down enough to fit in a cart. That was bad enough of its own, but they really wanted to add additional instructions to take advantage of the Atari's graphics and sound as well. Eventually they gave up and went looking for a 3rd party to do it for them, and eventually chose Shepardson Microsystems.
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Shepardson cut some features and added others to provide access to the capabilities of the new machine. The result required about 10k, so to cross the remaining gap to 8k, some of the core libraries were moved out of the language and into the operating system ROMs. This had the side-effect of allowing any other language on the Atari to use these routines as well.
Shepardson, or SMI for short, won the contract. They proposed cutting some features and adding others to provide access to the capabilities of the new machine. The result required about 10k, so to cross the remaining gap to 8k, some of the core libraries were moved out of the language and into the operating system ROMs. This had the side-effect of allowing any other language on the Atari to use these routines as well.
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Among the code moved to the OS ROMs was the floating point system, which was based on a 6-byte format. The 9k version of MS BASIC also used this format, while the much more common 11k version (Commodore, others) used an expanded 9-byte format. This meant the Atari has somewhat less accuracy, although in practice this meant little. In contrast, a very real issue was that the Shepardson floating point code was terribly slow, and this had a significant performance impact on almost all programs.
By the time SMI was hired, Atari was in something of a rush to get the BASIC. They were planning to show the machines in January 1979, and the contract required SMI to deliver the final version by April of that year. SMI completed it well in advance of the deadline, in October 1978, so Atari took an early version of the code with them to the CES show in January. To SMI's surprise, they learned that Atari had begun burning that version to ROM, even though it had several known bugs. SMI offered an updated version, but Atari didn't bother using it, shipping the buggy version for years.
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Among the code moved to the OS ROMs was the floating point system, which was based on a 6-byte format. The 9k version of MS BASIC also used this format, while the much more common 11k version (used by Commodore and others) used an expanded 9-byte format. This meant the Atari has somewhat less accuracy, although in practice this meant little (the IBM PC had even less). In contrast, a very real issue was that the Shepardson floating point code was terribly slow, and this had a significant performance impact on almost all programs.
This page (revision-114) was last changed on 24-Feb-2023 14:10 by Andreas Tartz  Top