From: Jim Brain (brain_at_jbrain.com)
Date: 2005-01-15 05:41:50
I am trying to design a 32 kB ROM cart for the VIC-20. I've found some RAM expansions that come close to the design I am looking for, but here's the rub: On a RAM cart, you cna just feed the BLK signals to a encoder and get the 2 high address bits. RAM is contiguous. No issues. In a ROM/EPROM, there are lots of options: 8kB ROM mapped into BLK1, or BLK2, or BLK3, or BLK5 16kB ROM mapped into BLK1, BLK2, BLK3 32kB ROM mapped into BLK1 32kB ROM mapped in as two separate 16kB images 32kB ROM mapped in as 4 separate 8kB images 16kB ROM mapped in as 2 separate 8kB images Does anyone have ideas on how to enable such configurations? If I didn;t have to worry about swapping address lines, I could simply put switches on the 4 lines. ON would enable that 8kB segment. Since address line swapping is needed to implement the above, I thought about some jumper blocks. Anyone have better ideas or know of projects already doing this? Jim -- Jim Brain, Brain Innovations email@example.com http://www.jbrain.com Dabbling in WWW, Embedded Systems, Old CBM computers, and Good Times! Message was sent through the cbm-hackers mailing list
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