Re: GMECM Digest V2 #192

[Dig <turbodig@yahoo.com>]

----
<trax@frederickmd.com>
Subject: '90 Calpaks and PROMs

A quick question from a newbie here ...
Those of you who are burning chips from years where
the PROM is soldered to
the calpak ... is it possible to make some sort of
adapter or do you have to
unsolder the PROM, erase the chip, reburn it, and then
resolder it to the
calpak?
----

Along the lines of "variations on a theme"....

It is possible to program them in-situ...with an
adapter to do it. 

Fortunately, the adapter is dirt-simple. I used 
a really long-pinned dual-row ribbon-cable header
(try digikey.com) that I split in half lengthwise.
(It needs to be 14 pins long)

Stick each half in a vise, and bend a 30 degree
angle on the bottom row of pins. Leave the uppers
straight. What you'll end up with will look like
this looking at it from the end:
   
   ||
   --
  /  \


Stick the straight pins into the PROM end of the
MEMCAL, and the other goes into the ZIF on your
EPROM burner (I use a Intronics Pocket Programmer).
Burn away!

Oh, yeah, there's that erasing part. I use a Datarase
II, which just isn't big enough to fit a whole memcal
into. So, out comes the tin-foil. Take the cover off
the Datarase, stick a tie-wrap in the little slot for
the safety interlock so the light turns on with the
cover off (insert appropriate Indiana Jones "Don't 
look at it" comment), place the MEMCAL window-side-
down on the eraser, and wrap the whole works with
the tin-foil to keep the light inside. (Ala baked-
potato)

It'll take a while longer to erase than regular 
eproms do just because the memcal isn't getting 
full UV light, but it will erase.

That being said, I found the above to be a hassle,
especially at the drags, so I went the direction 
others have displayed here by socketing the MEMCAL.

Rather than a ZIF, I used a low-profile gold-contact
socket, such that the blue cover fits back over the
top when you get done. If you're good at melting the 
EPROM label off with a hair dryer, you can even put
it back on, which makes it so clean even the dealer
mechanics can't tell the difference. :)

Also, I found that the best way to solder the socket
down to the MEMCAL was to remove the EPROM and 
contacts with a long stickpin (poke the terminals up
and out of the MEMCAL, go slow and be persistent).

Once you have the l-shaped contact pins out of there,
cut a thin piece of cardboard and stick it in the 
middle of the socket you're soldering 'em to. Line
the contacts up so they're evenly spaced, and solder
'em onto the legs of the socket.

Once you've got all the contacts soldered to the 
socket, pull the cardboard out, and stick the whole
works back in the MEMCAL shell. If you break a 
contact or two, don't worry- there's a couple extras
at each end of the ESC substrate you can steal.

HTH,

Dig
turbodig@yahoo.com
Sockittomesockittomesockittomesockittome...


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