Re: Steal RAM -- Question

["mdj" <mdj.mdj@gmail.com>]

Bryan Parkoff wrote:

>     If we are going to build peripheral card using RAM like AE RAMFactor
> card, we have an ability to force INHIBIT' to be low to disable CASEN',
> EN80', CD ROM, and EF ROM so they can steal $D000-$FFFF by using RAM card on
> periperhal slot rather than motherboard RAM or auxiliary RAM.  Will
> $0000-$01FF and $0200-$BFFF work to be used in peripheral slot?  I am
> curious.

I should also point out that the RAMFactor card, just like the Apple II
memory expansion card it's compatible with does not use INHIBIT', but
simply has 3 address registers to hold the memory card address, and a
data register to read/write it. For convenience, the card automatically
increments the address registers on an access to the data registers.

If you want to play around with it, the hardware addresses are as
follows:

$C080 - low byte of address
$C081 - middle byte of address
$C082 - high byte of address
$C083 - data byte

(Of course, all addresses are + slot number * 16)

You also need to do a read to the card firmware before it's registers
are active.

Matt