Dumping ROM combo chips

[Don.F.Broadus at ucm.com]

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
 
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/