Tech: Astrocade (Gorf, etc) DRAM timing

[Guest]

Archived from groups: rec.games.video.arcade.collecting (More info?)

Has anyone looked into the dram timing on bally astrocade boards?

I finally got boards fabbed for my redesigned gorf ram boards, and they
didn't worth on the first try (no real surprise there so I was wondering
if anyone had docs on the timing on the singals coming out of the astrocade
chips.

I know replacing 4027 with 4116 (or other newer DRAMs) works on some boards
(ie. Berzerk), but not on other (Carnival), due to timing isues with CAS,
RAS, G, etc, so before doing any serious debugging I was curious as to
how the timing looks. A straight 4116/4164 swap would have been an easy
design, but I used x4 DRAMs and thus need to multiplex the bus externally
to make the DRAM look like they have separate inputs and outputs, so I
could just be making marginal timing worse.

Guess I need to build up a test rig and slap a scope on the card cage...


--
Mark Spaeth mspaeth@mtl.mit.edu
50 Vassar St., #38.265 mspaeth@mit.edu
Cambridge, MA 02139
(617) 452-2354 http://rgvac.978.org/~mspaeth

 

[Guest]

Archived from groups: rec.games.video.arcade.collecting (More info?)

Hey Mark,
Can you drop me a line?