PROM Switching (Was PC war thread)

[Mark Romans]

Fred, which product is it specifically?  They have a bunch of products on
their web site.  HELP,  electronically challenged!
Mark.
-----Original Message-----
From: Frederic Breitwieser <frederic.breitwieser at xephic.dynip.com>
To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>;
diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
Date: Wednesday, March 18, 1998 7:24 PM
Subject: Re: PROM Switching (Was PC war thread)


>>  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
>