On 25 Mar 2006 09:06:03 -0800, "ve3tjd" put finger
to keyboard and composed:

Hi Guys:

I'm working on a "tractor performance monitor" from a farm tractor. It
uses an 6803U4 micro and I gather that the main program is stored on a
TC5518 static ram which is battery backed up. The problem came about
when the lithium cell went dead and the static ram lost it's contents.
I do have another working monitor, but does anyone know a way to read
it while it's still on the board? The board was manufactured in 1988.

I was thinking about soldering a 3 volt source to the ground and Vcc
leads, and then use my pocket programmer (II) to read the good one?
This static ram chip is pin for pin compatible with a 2716 eprom!

Can anyone suggest any other means of extracting the data, and
reburning it onto the original 5518?

If you could, also send me a reply to "tedd at ve3tjd dot com".

Thanks for any assistance.

Tedd, VE3TJD

Is the uP socketed? If so, remove it. Then wire the address and data
pins of your pocket programmer to the uP socket, and the CS pin to the
CS of the SRAM (or to the uP socket, if applicable). Connect the OE*
pin of the programmer to the R/W pin of the SRAM, through an inverter
if necessary. Now read the data as you would for a 2716 EPROM.

When writing the data, you may be able to "program" the SRAM as you
would a 2716 EPROM or a 2816 EEPROM - just don't connect the Vpp pin.

- Franc Zabkar
--
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