Microsoft open sources GWBASIC

Fred Cisin cisin at
Fri May 22 11:09:51 CDT 2020

On Fri, May 22, 2020, 1:43 AM jim stephens via cctalk <cctalk at> wrote:
>> Seems of interest.  Will be interesting to play with.

On Fri, 22 May 2020, Justin Goldberg via cctalk wrote:
> Interesting. I wonder if this is similar to the qbasic code in the dos 5
> (6?) source leak that's floating around. Or if Gates wrote any of it.

The Radio Shack Model 100 is believed to be the LAST BASIC that Bill Gates 
actively participated in.

"Similar"?  Well, sorta.

A little historical perspective:

1964 May : Kurtz and Kemeny (Dartmouth College) developed BASIC as a 
very/over simplified system for introducing beginning students to 
programming. "Beginner's All-purpose Symbolic Instruction Code"  As 
simplified as they could make it with as little overhead as they could, 
intended to be easier to GET STARTED with then FORTRAN.  It is unclear 
whether they intended that anybody might continue using BASIC once they 
had completed that beginner's introduction.

1975 January : Popular Electronics ran a cover feature story about the 

1975 March : Bill Gates and Paul Allen wrote a BASIC interpreter for the 
MITS Altair 8800 using Harvard's PDP-10.  The use was unauthorized, but 
student use had not been explicitly forbidden.  yet.
Allen completed the bootstrap program for it on the plane on their way to 
Albuquerque, to meet with Ed Roberts (MITS)

1975 April : Gates and Allen formed Micro-Soft
1979 January : Micro-Soft moved from Albuquerque to Bellevue Washington.
(Their phone number was (206) 255-8080)
1979 November : Microsoft dropped the hyphen

Developed BASIC interpreters (usually in ROM) for TRS-80 ("Level ii 
BASIC"), Commodore PET ("Commodor BASIC"), Apple ][ ("Applesoft BASIC") 
and others.

1981 : Contracted with IBM to write BASIC for 5150, and PC-DOS
(PC-DOS consisted of purchasing Seattle Computer's 86-DOS/QDOS ("Quick and 
Dirty Operating System"), and enhancing it.   There is extensive lore about WHY 
IBM contracted with Microsoft, instead of with Digital Research, Inc. for 
the operating system.   THAT is a different discussion.

1981 June 25 : Microsoft Incorporated

1981 August : release of IBM 5150, with BASIC in ROM, and BASIC and BASICA
on disk that added additional features (such as DISK) to the ROM BASIC.
Becuase the minimal 5150 came with 16K of RAM (soldered, with sockets to 
expand to 64K), BASIC was squeezed, and BASICA was less squeezed.

Microsoft began selling MS-DOS to OEMs.  Tim Paterson, Falcon 
Technologies, SCP, exclusive V non-exclusive license, etc. are another 
discussion.  Differences between PC-DOS and MS-DOS exist, but are mostly 
few and minor (such as IBMBIO.COM/IBMDOS.COM V IO.SYS/MSDOS.SYS)

Each OEM created their own BIOS ROMs, with occasional legal scuffles when 
IBM thought that they were TOO similar (IBM had PUBLISHED the source code 
for their BIOS ROM in the "PC Technical Reference Manual", but did not 
publish the source code of the BASIC ROM.)  "Clean-room" reverse 
engineering, "bug for bug compatability", etc. are other discussions.

Because other OEMs did not have legal access to the BASIC ROMs, they could 
not run BASIC.COM/BASICA.COM , which relied heavily on subroutines in the 

Microsoft created GWBASIC as a substitute. Almost the same as BASICA.COM, 
but did not require the BASIC ROMs, so that companies such as Compaq could 
provide BASIC.  (NO! Compaq could NOT run the reaal BASICA.COM.  They 
RENAMED GQBASIC.COM into BASICA.COM to avoid confusion for customers 
having both systems, thus creating lots of confusion for customers who had 
the renamed GWBASIC file on their disks)

Originally, G W BASIC stood for "Gee Wiz BASIC".  But Microsoft has 
forgotten that, and now claims to have no idea what GW stood for. 
(Similarly the file header flag of "MZ" that differentiated .EXE files 
from .COM stood for Mark Zbikowski)


and THAT is what is being touted here.

MUCH later, Quick-BASIC and QBASIC were created.

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