Editing Atari BASIC (section)

===Shepardson Microsystems===
[[Image:Basic computing language for Atari 8-bit computers.jpg|thumb|8K Atari BASIC cartridge]]

In September 1978, [[Shepardson Microsystems]] won the bid on completing BASIC.{{sfn|Wilkinson|1982|p=ix}} At the time they were finishing Cromemco 16K Structured BASIC for the [[Zilog Z80|Z80]]-based [[Cromemco]] [[S-100 bus]] machines.{{sfn|Wilkinson|1982|pp=iv-v}}{{sfn|Cromemco|1978}} Developers Kathleen O'Brien and Paul Laughton used [[Data General Business Basic]], an integer-only implementation, as the inspiration for their BASIC, given Laughton's experience with Data General on a [[time-sharing]] system.<ref name="SE Books">{{cite book |last1=Lorenzo |first1=Mark |title=Endless Loop: The History of the BASIC Programming Language |date=2017 |publisher=SE Books |location=Philadelphia |isbn=978-1974-27707-0 |page=106}}</ref>

Cromemco BASIC includes an extended [[floating-point arithmetic|floating point]] implementation using a 14-digit [[binary-coded decimal]] (BCD) format made possible using all 16 registers of the [[Zilog Z80]] processor. As it converts all data to the internal format at edit time, small constants like "1" use ~8 bytes of memory, and this could be a particular issue when storing arrays of numbers. To address this, the language also supports a smaller 6-digit BCD format.{{sfn|Cromemco|1978|pp=2, 3}}

Even the smallest BASICs on the 6502 used about 10K. For instance, [[Commodore BASIC]] used 9K but also relies on support from the [[KERNAL]],{{efn|Commodore BASIC used two main areas of memory, $A000-$BFFF and $E000-$E4D2.<ref>{{cite web |url=https://www.c64-wiki.com/wiki/Memory_Map |title=Memory Map}}</ref>}} while [[Applesoft BASIC]] is 10,780 bytes.{{efn|Applesoft was in the area from $D000-$F7FF, including the FP library.<ref>{{cite web |url=https://www.callapple.org/vintage-apple-computers/apple-ii/memory-map-apple-ii-with-applesoft-basic-loaded/ |title=Memory Map – Apple II with Applesoft BASIC Loaded}}</ref>}} To meet the goal of fitting in an 8K ROM, the new BASIC would be in two parts: the language itself on the cartridge and a 2K floating point library in the system's 10K ROM supporting only the 6-digit format.{{sfn|Wilkinson|1982|p=v}}

Atari accepted the proposal, and when the specifications were finalized in October 1978, Laughton and O'Brien began work on the new language.{{sfn|Wilkinson|1982|p=ix}} The contract specified the delivery date on or before 6 April 1979 and this also included a File Manager System (later known as DOS 1.0).{{sfn|Wilkinson|1982|p=v}} Atari's plans were to take an early 8K version of Microsoft BASIC to the 1979 CES, then switch to Atari BASIC for production. Development proceeded quickly, helped by a [[Consideration# Bonus_clause|bonus clause]] in the contract, which led to the initial version being delivered in October. Atari took an 8K cartridge version to CES instead of Microsoft's.{{sfn|Wilkinson|1982|p=x}} [[Atari Microsoft BASIC]] was later a separate product.<ref>{{cite magazine |first=Charles |last=Cherry |title=BASIC Bonanza |magazine=Antic |date=June 1987 |url=https://www.atarimagazines.com/v6n2/BASICBonanza.html}}</ref>