Microsoft open sources GWBASIC

Jim Brain brain at
Thu May 28 15:54:10 CDT 2020

On 5/28/2020 12:38 PM, Liam Proven via cctalk wrote:
>> Yes.  TRS80.
>> It had a memory map that was incompatible with CP/M.  BASIC in ROM at the
>> bottom, and RAM at the top.
> Which one?
> As they're purely a theoretical concept to me and AFAIK I've never
> actually touched one, the profusion of models is very confusing, and
> I'm  not aware of an idiot's single-para overview.
> I vaguely know of:
>   • TRS-80 Model 100 (8085), pre-laptop portable
Rebadged Kyotronic 85.  Was pretty well received in US by journalists 
and those who needed some computing power on the go.
>   • Tandy 1000 (PC compatible)
Yep, there's a whole line (HX, LX, EX, etc.)
>   • TRS-80 Model 2000 (*before* the 1000?! Also kinda-sorta PC
> compatible, nearly?)
Maybe due to other vendors having a "1000" machine, this put Tandy in 
front.  Or, depending on what the Tandy 6000 was introduced, maybe they 
had a product lineup dreamed...
>   • TRS-80 Colour, AKA CoCo -- 6809
Started life as a farming-related Videotex terminal.  Pics will show the 
amazing similarity.  Was a joint venture between Motorola and Tandy, and 
used essentially the 6809 reference design.
>   • TRS-80 Pocket (no idea)
These were all rebadged items from other manufacturers (PC-1,II,34, 
etc..).  Went all the way up to 8.  But, folks prefer the 2, as it was 
most expandable, etc.
> Then there seem to be about 42 different computers called TRS-80 Model
> X where X is either a Roman or Arabic number under 1000, after which
> it all changed. Except 2000 comes before 1000. Obviously.
Al PC compatibles.
> The TRS-80 Model I, Model II, Model III, Model 4, Model 12, Model 16,
> etc. I know nothing at all about these but I believe the III ran Xenix
> on a 68000 and had some resemblance to the Apple Lisa, which would
> seem to preclude any relation to the Model I & Model II -- and
> Wikipedia suggests that the Model II is totally different from the
> Model I.

IN the beginning, there was the Model 1 (actually, it was called the 
Micro Computer System at intro.  It got back-numbered when the II came 
out).  It was a fat KB shell with a computer board in it (think C64, but 
less aerodynamic :-)  Fred's right, it should be considered a home 
computer.  No color, Z80 1.7MHz (half the 3.59MHz of NTSC TV signal fame).

FOr the business crowd, TANDY designed the Model II, which is 
distinctive due to the 8" drives used.  In fact, I think it's the only 
mainstream US computer offered with such drives straight from the 
factory, though someone will correct me if not.

Enter the FCC, and the 1981 regulations concerning EMI.  The Model I 
didn't pass muster, so the Model III (which was mainly an extension of 
the Model I specs, but in a nicely polished case, including monitor and 
drives.  It's what people think of when they remember the TRS-80 
computers, I think.

> But it claims the Model III is compatible with the Model I. (Wut?)
Yep, and the 4 was a follow on from the 3.
> It very quickly all becomes rather surreal and I rapidly lose track
> (and interest, TBH.)

> I suspect a graphic might be needed to disentangle it.

> So it goes:
> Model I → Model III → Model 4
> *And*
>>    Model 2 → Model 12 → Model 16


II-12/16B (16B had the card cage)

I see the 16A and the 12/16B as different sublines, as the II/16A used a 
passive backplane with cards, while the 12/16B/6000 had a motherboard 
with the z80 on it, and the card cage was for extensions (and the 68K card).

Both sublines merged back together with the 6000

Units were Z80 based, but a 68K daughtercard was sold to enable Xenix.  
The 6000 has an 8MHz 68K, I think the rest are 6MHz

> ... ?
> Where do the VideoGenie and Coco fit in?
VideoGenie is not a TANDY item (most folks consider it a clone of the 
Model I), and the Coco was a different home computer line with color.

Jim Brain
brain at

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