G'day folks,
Paul explained why you have to use two EPROMs as a minimum, and I agree
completely. I'll direct you, Ray, to page 4 of the schematics. Look
at the chips that the EPROMs feed. You'll see how the the data at
even addresses is allowed through, but the data at odd addresses is
latched up. (Note that I could have it in reverse...the data at odd
addresses is let through, but the data at even addresses is latched up.)
You're going to have to change the architecture quite a bit to handle
this. Paul's suggestion of using a 16 bit wide EPROM is probably the
most practical way to quickly overcome the limitations of this architecture
BUT I wouldn't suggest it since very few people will be able to duplicate
your efforts!! Think how hard it is for you just to burn regular EPROMs
like 2732s, etc. Imagine how much harder it would be to buy the 16 bit
wide EPROM and then find facilities to burn it!!!! Stick to two EPROMs.
As to documenting the 2716->2532 information, first I have to give some
background. UE=U7, LE=T7, UO=R7 and LO=P7, where [P-U]7 is the socket
location on the Cinematronics motherboard and the [UL][EO] stands for
one quarter of the whole Cinematronics program. If you combine the lower
and upper quarters where lower goes at 0000H of the 2532 EPROM, then you
put E at T7 and O at P7. If you reverse how you combine the lower and
upper quarters where upper goes at 0000H of each 2532H, then you put
E at U7 and O at R7.
Interestingly enough, Space Wars puts it's masked ROMs at U7 and R7.
What do you think Paul?
Steve Ozdemir
ps - Sorry I haven't gotten the questions to you yet, Paul. Did you
pick up the equipment from my grandparents?
pps - Did I mention that I got my EPROM burner working on my PC this
weekend? Rick got me an EPROM eraser, so I'm all set to go!!! Not
a bad set up given that I paid a total of $50 for all the parts...too
bad I had to wait 2 years before all the parts came together. It's
always a trade off, spending more money or more time.
