Re: [stella] EPROMs

Subject: Re: [stella] EPROMs
From: Kevin Horton <khorton@xxxxxxxxxxx>
Date: Mon, 03 Sep 2001 01:19:20 -0500
At 18:51 9/2/01 -0400, you wrote:

2 of the chips I got are labelled `M2732AFI 21V Fast', and appear to be
brand new. Are these things fully compatible with the standard 2732? I'm
assuming that EPROMs are like RAM, and will run just fine at a slower
speed than they are rated, but what about the programming voltage/timings?

Plain old 2732. 21V programming voltage, and "Fast" means you can use quick pulse to program it instead of the usual old 50ms programming pulse.

And yes, you can always use a faster EPROM on a slower bus (same with RAM and most other devices).

The rest of the chips I got are 27C128's. I assume the C means CMOS. I
haven't yet found a data sheet for these, but somebody on this list can

16K bytes, and yup, CMOS so they don't draw much power.

probably give me the short answer: Will these 27C128's (a) work in a
programmer designed for regular 27xx series, and (b) assuming I get them
programmed, will they work in a 2600 cartridge? (Yes, I have 74xx inverters)

If it can accept 27128's then it will work just fine. BE SURE TO CHECK YOUR PROGRAMMING VOLTAGE. The chip should be printed with it on there. 12.5V or 21V is usually what's used. The smaller die chips are usually 12.5V. If the chip isn't marked, program it at 12.5V and if it doesn't work, then try 21V.

Also, if the EPROM has an "A" appended to it (27C32A) that means 12.5V programming voltage usually. Sometimes "B" or even "C" is seen. This can mean different things, but usually 12.5V programming voltage. Using a Vpp higher than the chip's rating will destroy it (i.e. 21V Vpp on a 12.5V Vpp part). Note that if you are just reading an EPROM Vpp does not matter since it is not turned on during the read (if you want to be safe, you can set it to 12.5V).

Anyway, if worst comes to worst, I have got one regular old 2732 I can

Also, you can use the 27C128's. You can make a simple 4 game multicart (so you can burn 4 tests to the EPROM before having to erase it) or simply wire the unused address lines to ground so it selects the first 4K only.

use... and the Hamfest trip was a blast, even though I'm not really into
ham radio.

Hamfests are great. I've gotten the coolest crap at those including some Gameline modems, new in the box. :-)

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