View Full Version : Looking for a Dual Systems CMEM memory board manual.

January 27th, 2016, 07:56 PM
I am looking for a Dual Systems CMEM memory board manual. If the manual is not available, I am hoping that someone else has a CMEM board and can tell me what ICs go in positions U30 and U40. As can be seen in the pictures these two chips are missing.



January 28th, 2016, 12:57 AM
Yes, unfortunately I can categorically state that DUAL documentation is just almost non existent. I googled it so many times of the years. So I would very much lookforward to somebody out there reading this and proving me wrong.

Regards marcus b.

February 13th, 2016, 08:30 PM
Just a followup on the CMEM board. I managed to find two pictures of the board online, neither of which are very clear. However, I was able to determine from one that the U40 chip is a 74LS245. That left the U30 chip to figure out. I traced back from all of the pins of U30 enough to determine how it functioned in the circuit. I realized that the chip must be a quad dual input nand chip which is a 74LS00. I installed both chips and had a successful test of the board. So, I now have a working CMEM static memory board.