Re: CBM's CP/M, Z-80 carts for the 64

On 19/12/12 22:47, silverdr@wfmh.org.pl wrote:
> Do I recall correctly that those carts were unreliable / unstable? Also, wikipedia states: [..] the cartridges only worked on early-model C64s from 1982 and were incompatible with later units [..] What do the authors mean there?
>

 From Brian Bagnall's book:

"Bil Herd wanted to make his C128 compatible with the existing Commodore 
CP/M cartridge, which used a Z80 processor. The cartridge was designed 
by an engineer they dubbed 'Shooting Star'. "This guy was supposed to 
design a Z80 cartridge for the Commodore 64," explains Herd. "One of the 
things I noticed when I did the C128 was that the Z80 cartridge didn't 
work in the C128, and it really didn't work in the Coomodore 64; they 
just thought it did."

"Herd discovered the problem. "I'm going through this pile of papers a 
year later and I find a schematic for a Z80 cartridge," he recalls. "I 
open it up and look at it, and low and behold it's the Z80 coprocessor 
card for the Apple! Shooting Star ripped it off and that's why it didn't 
work."

"Herd studied the problem and realized the CP/M cartridge used more 
power than the C64 supplied. "I got paid to be cheap and I couldn't 
afford to pay for half an amp that I would only use if somebody had the 
CP/M cartridge," he says. "I couldn't afford to add five dollars to the 
cost of [the C128]."

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