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Building a lot Core memory for a PDP8 Straight 8

rorypoole

Veteran Member
Joined
Dec 8, 2004
Messages
585
Location
UK, Surrey
I have wanted a PDP8 straight 8 for over 10 years, recently I found a seller on ebay selling 0.5mm~ and 1.1mm~ raw cores for use in core memory, dated 1980~ this kicked off the PDP8 building project, I want to use the PDP8 as a CNC machine controller, so need 32kw of core memory. so I bought 9 boxed of 0.5mm dia. raw cores, I decided on the smaller cores as they would work faster and I have no data sheet on them.
each core memory needs to store 4096 bits and as its a 12bit computer I will need 12 planes per 4kw, and one more as I want the parity option, so that is 53,248 cores for the first 4kw! and 425,984 cores for the full 32kw, that is 104 core memory planes that need weaving, each plane will be a 64X64 matrix, with inhibit and sense wires, so 4 wires per core, I have worked out I need 0.08mm wire to fit!
 

rorypoole

Veteran Member
Joined
Dec 8, 2004
Messages
585
Location
UK, Surrey
The reel of 0.08mm magnet wire has arrived, it is thinner than I was expecting! but I now have a lot of it. I will now design a core memory testing rig for 1 bit core memory .
 

rorypoole

Veteran Member
Joined
Dec 8, 2004
Messages
585
Location
UK, Surrey
I managed to loop some 0.7~ copper magnet wire threw the 1.2mm dia. core, 4 times and the 0.08mm magnet wire threw the 0.5mm dia. core 5 times! I am pleased that it was not as hard as I was dreading.
 
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