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

On 2012-12-19, at 13:42, Daniel O'Shea 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:
> [...]
> "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]."

So does it boil down to the power supply? Would adding external power to the cart in such case help make it work reliably? This would suggest that the later 64 PCBs supplied less power than the first ones, which I sort of doubt. Or was there something else? That would supposedly prevent the cart from working with later versions of the 64?

-- 
SD!
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