GM 747 EPROM

[Mika.Helander at softbit.fi]

There is no problems using bigger EPROMs in 2732A carrier. Just use pull-up
resistors for greater-than-2732-eprom address lines and dip-switch block or
BCD switch like I used.

I know that for experience; my VAN is having '7747 and I replaced stock GM
eprom carrier by normal carrier for easier chip swapping. Later on I wrapped
32-pin PLCC carrier (for Am29F040) on top of 24-pin EPROM carrier so that
2732-size address pins with data bus and chip selects straight to 24-pin
carrier. The I grounded A13-15 and pulled up with 10k resistors A16-19 and
wired to grounding 10-pos BCD switch. Now I can switch easily between eight
"EPROM"s... And no need for UV-eraser, just program Am29F040 with
5-volt-only programming device.

-Mika

> For the GM 747 EPROM, I noticed all the images are 4096bytes 
> (32Kx8 bits).
> Does this mean the 13th address bit (most significant) is not 
> used? If this
> is the case, is it connected to the computer, or would it be 
> possible to
> burn two 32Kx8 images to a 64K eprom, and use a simple logic 
> high/log on the
> A13 pin to select which image to use. I got this idea from 
> the 6-in-1 design
> idea on the website, to give credit where it's due.
> ----------------------------
> Jove Malcolm / TheDrip
> drip at home.com
> http://www.sendon.net/~drip
> 1989 Chevy Blazer
> 1980 Pontiac Trans Am WS6
> 1960-1990 Combined pile of rust
> approximately the size of a vehicle
> 
> 
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