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From: toddpw@tybalt.caltech.edu (Todd P. Whitesel)
Newsgroups: comp.sys.apple2
Subject: Re: EEPROM burner for the II?
Message-ID: <1990Jul9.192328.22177@laguna.ccsf.caltech.edu>
Date: 9 Jul 90 19:23:28 GMT
References: <1990Jul8.063202.19289@agora.uucp> <26793@athertn.Atherton.COM>
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Organization: California Institute of Technology
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EEPROM's are easier to work with than EPROMs. An EEPROM will act just like an
EPROM in that it remembers everything when the power is off, but you don't
need a special programmer to program an EEPROM.

I have a card I wire-wrapped for my II which has a socket on it that will
accept a 6264 static RAM, and memory maps it (bank switch four times) into
the peripheral ROM spaces ($Cn00 and $C800-$Ceff). I originally used it on the
II+ to hold a prodos RAMdisk driver for a Saturn 128K card.

But enough of that. The 2864 EEPROM plugs into _exactly_ the same socket as the
6264, and you program it _in_that_socket_ by writing a byte at a time to the
EEPROM and then waiting until it reads back correctly. The EEPROM has little
internal circuits that handle the erasure and burning process, and you can
reprogram each byte independently, without having to erase the whole chip first
(big win here).

It should be possible to use an EPROM burner to program a EEPROM, but I'd have
to check my notes at home before I'd stand by that. I think the program voltage
(12V) pin on an EPROM is not connected on the 6264 and 2864, so you could use
them in the same socket as a 2764.

Todd Whitesel
toddpw @ tybalt.caltech.edu