PROM Switching (Was PC war thread)

[Frederic Breitwieser]

>  Hey, Fred.  I've got the small end of my cone shaped hat at my ear, so I
>should be able to get everything now. : )

Howdy :)  At www.dalsemi.com, they have data sheets for their static ram.
Anyone familiar with the EISA PC architecture that Compaq tried to make
famous - this was one OEM application of these chips.

>In a general sense, how does the chip you mentioned replace an eprom?  And
how
>do you program it?

Its a pin for pin compatible with most of the 27xx series EPROMS, and you
can program it in the same eprom programmer, or build your own interface -
its a ram chip.  I brought it up since I figured a lot of us are making our
own stuff, this shouldn't be too hard to do - I've done it, though not
recently (and for an alarm system too, but the theory is the same).

Anyway, there is no -15V or anything strange to program it - its a static
ram chip with a litium battery soldered to it, epoxied over.

>with 10 chip slots.  I could never understand why anyone would need that
many.

Me neither... I could think of three - drag racing, track racing, and
emissions testing.

>Are you suggesting electronically switching from the test prom to a stock
one,
>?reprogram? the test prom, and switch back while the car's running?

Personally, I wouldn't, unless you were absolutely sure the chips code were
identical - otherwise its possible for the program on the EEPROM to get
lost and the ECM halts (that's bad, but restart the car and it goes away).
The data could be very different, that's not an issue, though upon
switching, the car might hiccup slightly if the chips are radically different.

>And on a side note, have you checked out any Kenne Bell stuff?  Not that
they'd
>have any 4 valve heads....

Not yet :)

Frederic Breitwieser
Bridgeport, CT 06606

Homebrew Automotive Website:
http://www.xephic.dynip.com/

1993 Supercharged Lincoln Continental
1989 HMMWV
2000 Buick-Powered Mid-Engined Sports Car