1979 Bigtrak - Control Chip

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Neil Middlemass
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1979 Bigtrak - Control Chip

Postby Neil Middlemass » Sat Mar 11, 2017 10:43 pm


Apologies if this is off topic, please delete if it is.

I have acquired a Bigtrak from the early 1980's and I think the control chip isn't functioning.. The chip is a TMS100 and is MP3301ANLL E

Would it be possible to read and extract the code from a working chip and write to an EPROM or something similar to replace the duff one??

It is quite easy to find the code on the intranet using Google but that is where my skill stops...

Would be lovely to get this old thing working again.

Many Thanks


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Re: 1979 Bigtrak - Control Chip

Postby BigEd » Sat Mar 11, 2017 11:10 pm

I don't think there's any way to reprogram the chip or run it with external ROM: it's a mask ROM, which means it's fixed at manufacture.

Just possibly you could remove the chip and replace it with an emulation... but if possible, replacing with the same chip from another device (perhaps one with mechanical breakage) would be a great deal easier.

The TMS1000/TMS1070 were basic microcontrollers with 1 KB of masked ROM and 64 x 4 bits of RAM

- http://www.cpu-world.com/CPUs/TMS1000/index.html

See also http://www.robotroom.com/BigTrak.html

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Re: 1979 Bigtrak - Control Chip

Postby Seldon2k » Mon Apr 17, 2017 2:06 am


My first thought was remove the TMS1000 and use a ribbon cable to go to an Arduino Nano or Mini.

https://commons.wikimedia.org/wiki/File ... _Board.jpg

A sketch could be written for the Arduino that would emulate the functions of the Bigtrack.
These are listed in the user manual.

Then I thought, I can't be the first one to think of this, so a few seconds searching revealed:-

https://zuzebox.wordpress.com/2010/11/2 ... -big-trak/


Hope this helps,
Terry (Seldon2k)

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