Posted By
SVS
on 2015-02-23
02:52:58
 |  Re: Bankswitching of Plussy and its programming
The problem of reading RAM under ROM was known by Plus4' OS creators. Hence they did put a special routine for that purpose.
Every time the Plus4 is turned on, the routine is copied onto $07D9...
Working info:
- Write on $7DF the zero-page address where is stored the RAM address of location to be read;
- .Y is used to index the reading (then set .Y=0 if no indexing is requested)
- JSR $07D9 and you'll have .A with the read value.
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