EPROM won't program correctly

[Dan Plaskett]

Tim

Could be the ZIF  They are notoriously bad on the Pocket Programmers.  I've
got a friend that has to push down on the chip every time he programs one.
You might try that or contact Pocket Programmer for a replacement unit. BTW.
The other thing you might check is to make sure you have a 27C256 chip.  I
was having a similar problem and found out the chip I thought was a 27C128
was actually a 27C256.  You might be dealing with a 27C512 and not know it.
If that happens to be the case you need to load the file twice  (or create a
special BIN with it twice) and choose 27C512 as the chip you are
programming.  Good luck.

Dan Plaskett

----- Original Message -----
From: "trax" <trax at frederickmd.com>
To: <diy_efi at diy-efi.org>
Sent: Thursday, May 11, 2000 8:30 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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