Login
Back to forumSee the full topicGo to last reply

Posted By

Litwr
on 2016-12-26
09:31:27
 Re: Porting to Commodore Plus 4 of my game Genius, memory/bitmap mode questions..

IMHO it is easy to use 64 KB RAM permanently. Just make IRQ and KERNAL calls wrappers. For example, IRQ wrapper maybe something like the next code

bintr
STA $FF3E ;enables ROM
STA *+11 ;saves AC
LDA #>rintr
PHA
LDA #<rintr
PHA
PHP
LDA #0
PHA
TXA
PHA
TYA
PHA
JMP ($314) ;ROM IRQ handler
rintr
STA $FF3F ;turn RAM on
RTI

You should place bintr address to $fffe.



Back to top


Copyright © Plus/4 World Team, 2001-2024