Re: Steal RAM -- Question

["Bryan Parkoff" <nospam@nospam.com>]

"mdj" <mdj.mdj@gmail.com> wrote in message 
1162911536.994535.141680@h54g2000cwb.googlegroups.com">news:1162911536.994535.141680@h54g2000cwb.googlegroups.com...
>
> Bryan Parkoff wrote:
>
>>     Okay, I understand.  When AE RAMFactor or any memory card is 
>> installed
>> in slot 1 through 7, SELECT DEVICE is mapped in C08X * 16 and I/O DEVICE 
>> is
>> mapped in Cx00-CxFF.  If you build new peripheral card, are you limited 
>> to
>> use 16 I/O switches in C08X * 16 while reading firmware including I/O
>> switches from I/O DEVICE ROM.  Correct?
>
> If you build a new card, you can do what you like :-)
>
>>     When AE RAMFactor card is active, data should always be accessed in
>> motherboard RAM while it can be transferred from motherboard RAM to
>> RAMFactor card.  It is impossible to disable motherboard / auxiliary RAM 
>> and
>> use RAMFactor card as primary RAM $0000-$FFFF except $C000-$CFFF.  Only
>> other RAM card can disable motherboard / auxiliary RAM.
>
> Data from the RAMFactor, or any other 'slinky' card is only available
> through a 1 byte window in the I/O space.
>
> I'm not aware of any memory card that uses the INHIBIT' line to expand
> memory, with the exception of multibank memory cards for the II/II+
> that provided multiple language card banks.
>
> It's difficult to conceive of a design that utilises this feature,
> doesn't do what either slinky cards or RamWorks style cards already do,
> and doesn't clobber something in some way as to make it undesirable.

Matt,

    Please read page 5-24 of "Understanding the Apple //e" manual.  It 
explains that if INHIBIT' is low, motherboard RAM, auxiliary RAM, and CD+EF 
ROMs are disabled and it steals $D000-$FFFF into peripheral card RAM.  It 
does not say if it steals $0000-$BFFF.
    I do understand that AE RAMFactor card is not designed to steal 
$0000-$BFFF and $D000-$FFFF.  It is done using $C08X * 16 to read one byte 
data from AE RAMFactor card on the databus.  Correct?  I will study AE 
RAMFactor card later.  Is it the same what AE RAMWorks III is doing.  I 
can't imagine if AE RAMWorks III card can do to steal $0000-$BFFF without 
loading byte data through I/O.

Bryan Parkoff