Microsoft open sources GWBASIC

Jim Brain brain at
Sat May 23 22:41:54 CDT 2020

On 5/23/2020 10:25 PM, Fred Cisin via cctalk wrote:
>> Again, misleading.  The Z80 was not a design goal.  a 2MHz C64 
>> compatible with 80 columns was the design goal.  THank the Z80 on 
>> some Marketing shmuck that promised CP/M compatibility on the unit 
>> (thinking the C64 CP/M cart would work, which it can't, because the 
>> cart is badly designed, I am told it was a bit f plagiarism from an 
>> Apple II CP/M card, but failed to take into account the strange C64 
>> bus cycle).  Bil is around and can happily tell you the story of 
>> simply designing the Z80 cart into the main motherboard to checkoff 
>> the requirement and quit having to fight to get the cart to work.
> I met a few early purchasers of the C128.
> They were C64 users who felt that they ALSO needed a CP/M machine, and 
> it was handy to have both machines in one case.

I don't completely fault the Marketing person for suggesting it. But, as 
Bil tells it, when he pushed back, saying everyone at the office knew 
the CP/M cart only worked on Rev 1 64s, Management (remember, Jack was 
gone now) noted that it had been promised to dealers in hard copy, so it 
had to happen. :-)

I also think the hardcopy promosed 512kB RAM, but Commodore cheaped out 
on the MMU for the C128, so only 128kB is possible inside the machine.  
Some extremely talented CBM HW gurus figured out how to leverage/abuse 
the UltiMAX mode of the original 64 to enable DMA transfers on the cart 
bus, which is why the 1750 RAM Expansion Unit exists.

> It's possible that with a few more iterations, they might have been 
> able to get the Z80 side and the C64 side to work together better.

I think they would have.  Bil was not an expert on the Z80, he did as 
well as he could under time constraints.  If it had seen another 
revision, perhaps a full speed 4MHz Z80 would have been possible.

But, like I said, I think the C128 was just a cash grab to keep the 
company afloat until Amiga sales could support it.  I remember in late 
1980's, Commodore tried everything to get folks to trade in their 64 for 
an Amiga (500 or 600, I think). They wanted to kill of the 64, as they 
didn't intend to support it any more. And, those of us who did not move 
onto the Amiga were sore about their for years.  But, looking back now 
as an adult and with more knowledge of economics, it seems totally 
reasonable.  The 8-bit line had run it's course from a sales 
perspective.  16/32 bit machines commanded higher prices, had more 
expansion options, etc.

I'm not as much into Apple, but I believe the IIGS was a similar beast. 
Speed limited so as to not poach Mac sales, and was designed to bolster 
some cash flow until the sluggish Mac sales sped up. The story I heard 
from many sources was that Bill Mensch (who I believe Jack or at least 
Commodore helped set up Bill's Western Design Center) delivered the 
first version of the '816 to Apple, and the tech folks complained 
bitterly about some technical aspect of the addressing, essentially 
forcing Bill to redesign that aspect.  I've always wondered what the 
first version had, what the issue was, and what was done to address it 
to Apple's satisfaction.


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