Dumping ROM combo chips

[Bruce Plecan]

-----Original Message-----
From: Don.F.Broadus at ucm.com <Don.F.Broadus at ucm.com>
To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
Date: Wednesday, November 25, 1998 10:00 AM
Subject: RE: Dumping ROM combo chips


>Could I bother you for info on  Prom ABHC 7377 out of a 1227747 ECM from a
>1987
>Full sized GMC Van.  Would this PROM work on a  stock 5.7L  engine

Yes, it's out of a G Van.  If the 5.7 is in something much lighter,
different then the match will be less than perfect drivibility wise.
GM looks at lots of things when they do a calibration, the finer
it is tuned the less transferable it is.  
Bruce
> 
>Thanks Don
>
> -----Original Message-----
> From: Ludis Langens [SMTP:ludis at cruzers.com]
> Sent: Wednesday, November 18, 1998 2:55 PM
> To: Diy_efi
> Subject: Dumping ROM combo chips
>
> Many of the older GM ECMs use a 40 pin DIP combination ROM/RAM/IO
>chip. 
> (The pinout is on my web site.)  This chip has 4K bytes of ROM, 128
> bytes of RAM, and 8 digital I/O lines.  The chip receives all 16
> processor address lines and does it's own address decoding.
>
> If you wish to read out the ROM from one of these out of circuit,
>you'll
> need to provide an E clock signal.  I wired up an adapter to read
>these
> chips in a PROM reader as a 27512.  The RAM and I/O appear to read
>OK
> with E tied high.  The ROM however doesn't.  The PROM ~OE signal
>needed
> to be inverted and applied to the combo chip's E input.
>
> -- 
> Ludis Langens                               ludis (at) cruzers (dot)
>com
> Mac, Fiero, & engine controller goodies:
>http://www.cruzers.com/~ludis/
>