Canon Cat -- what's it really like?

Eric Smith eric at brouhaha.com
Mon Mar 7 04:43:38 CST 2005


Ethan wrote:
> My recollection is that the Apple II motherboard pre-decodes address
> ranges on behalf of the cards and does _not_ present A0-A15 raw to the
> slot.

A0-A15 are on pins 2-17 of the slot connector.  They are buffered, both
to increase the drive capability and because the standard 6502 didn't
provide a way to disable the on-chip address drivers, which is necessary
to support DMA.

Most cards don't need to use A12 through A15 because of the available
decode lines, but they're certainly available.

Eric






More information about the cctalk mailing list