Re: EPROM won't program correctly

["Jim Wilson" <Wilson.James4@worldnet.att.net>]

I use Eprom Exe. in Windows 98 and have no problems. Before I program I use
(1)eprom erace and (5)check eprom for compatibilty to buffer. If program is
stopping before finish and you are coming up with"eprom not programed" then
I would suspect the 27c256 Eprom.






-----Original Message-----
From: trax <trax@frederickmd.com>
To: gmecm@diy-efi.org <gmecm@diy-efi.org>; diy-efi@diy-efi.org
<diy-efi@diy-efi.org>; Kevin Crain <kevin@warpten.com>
Date: Thursday, May 11, 2000 6:21 AM
Subject: EPROM won't program correctly


Everytime I program an EPROM it will not verify to the buffer.

Equipment:
Pocket Programmer
Datarase II
IBM Thinkpad P133 w/ 40Meg RAM (Windows98 with optional DOS boot)
27C256 EPROM from 1990 5.7 IROC desoldered from the carrier
.BIN file from same chip (obtained successfully by reading EPROM using above
equipment and verified in TunerCat against another '90 f-body 350ci image).

Here are the steps that I performed:
Erased EPROM in Datarase II
Booted laptop to DOS (no events in autoexec; config.sys has...
- DEVICEHIGH=c:\WINDOWS\HIMEM.SYS
- DOS=HIGH,UMB
Ran the program called eprom.exe
Choose 27C256 EPROM
Put EPROM in ZIF (nice tight fit)
Blank EPROM check succeeds consistently
Load buffer with FFs and verify EPROM to buffer (successfull)
Load stock .BIN for '90 5.7 from hard disk (same image I took from the chip)
Program EPROM
Verify EPROM to buffer

The verify EPROM to buffer always fails.  There are so many addresses that
are different that the screen just scrolls and scrolls with the errors.  I
tried this method many times (erase, program ... erase, program ... etc).
Blank check always succeeds and the verify always fails.  Furthermore, the
programming seems to always stop on its own before it reaches the 7FFF
address.  Am I doing something wrong?  Any ideas?  Tonight I am going to try
a different laptop (486/50MHz).  I will eventually try a different EPROM
(should have fresh EPROMs on Monday).  But, I find it hard to believe that
it would be the EPROM since this is the first time that it has ever been
erased and it has always worked successfully in the car.  All the legs on
the EPROM are perfect.  It seems to fit nice and tight into the Pocket
Programmer's ZIF.

Extra Info:
Using the concealed option 88 reveals...
Vpp=12.5 Port Address=0378  Pass=1  Pulse=82  Port Delay=5  Add Strobe=On

Any help you can give is very much appreciated.

Tim Siford




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