Posted By
filker
on 2018-01-16
05:36:28
|  Re: Possible 8501 replacement kit?
Yes. The same guy mentioned in the first link given in this thread sells them.
BTW, I was planning to do it on my way, and last night I examined the original kernal to see the modifications necessary for 6510. 6510 has no last two bits at the $01, which are used by the kernal with a tight code, such as:
BIT $01
BVS ....
or
LDA $01
ASL
BPL ....
These code snippets cannot be changed in place since we can only use the bit 3 and bit 5 instead (for serial data and clock inp). So, an ugly patch is needed in these codes.
Though, I'll also examine the jiffydos kernal, I hope it is less harmful to change it.
BTW, since we use 6510 in Plus/4. I first changed the default screen, border and text colors in the kernal ($334D, $3351, $187F) to C64 colors: $16, $46, $16.
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