Re: Zip GS questions

[dempson@actrix.gen.nz (David Empson)]

<pubpc1@library.ucla.edu> wrote:

> Barry, yes it will work.  I'm in the dark about how the Zip maps memory,
> but from experimenting on the Zip, it seems that any time you have four
> 32k x 8 SRAMs installed, you can set the DIP switches to any of the
> configurations from 8k all the way to 64k.

32K and 8K static RAMs are pin compatible, except for two pins: A14 (on
pin 1 of a 32K RAM) is not connected on an 8K RAM, and A13 (on pin 26 of
a 32K RAM) is replaced with an active-high chip select signal on an 8K
static RAM.

As the ZIP has switches to tell it what size of RAM is installed, it
should have no trouble using only 8K of 32K RAM chips.  It just holds
pin 26 high and can set pin 1 either way as it sees fit (as long as it
does it consistently).

The 8K vs 16K and 32K vs 64K settings just tell the ASIC how many socket
pairs are used.

-- 
David Empson
dempson@actrix.gen.nz
Snail Mail: P.O. Box 27-103, Wellington, New Zealand