Ferrite Core Memory Project  - Page 1
Forum section: electronics / projects

author: ihearta380
author_rank: Newbie
timestamp: March 04, 2022, 06:27:57 pm
content: Hello I need a little help navigating this ferrite core memory technology. My end goal is to use it in a calculator something straight forward. However I understand the writing process to each core but how is reading accomplished? Do you have to measure the voltage on the sense wire and flip each of the bits while collecting the bits on the sense wire? Because I feel of you flipped all the bits at once you would have several voltages just summed together. Also my memory pane is a 64K in size and has a front and back that are mirror and in parallel with the front. The sides have 4 windows and has 64x(s) and 64y(s) that I counted. How should I go about driving all these it seems far fetch to have 16384 transistors. As for the sensing and logic should I use a fpga and opamp or ADC and do some DSP in the fpga for the weak signals produced from the sense wire. I want to put this all in a 6x6x2.5 inch enclosure so it's going to be tight. Any suggestions would be great help.

author: pqass
author_rank: Super Contributor
timestamp: March 04, 2022, 07:57:07 pm
content: Reading is destructive. Only the core at the intersecting row+column will receive the full saturation current so if it flips, that's what (and only) the sense wire sees. Here is an extensive writeup of how it all works:https://web.archive.org/web/20170205194857/http://www.cs.ubc.ca:80/~hilpert/e/coremem/index.htmlYou'd drive the array with something like 64+64 transistors * 2 (if each line needs a push-pull driver). I vaguely remember reading about multiple sense wires and inhibit wires too. You'll need to first figure out what topology you've got in front of you. Do you know what machine it came from? Any markings?For contrast, here's a simple core mem implementation (follow the Arduino Core Memory shield links):https://hackaday.com/blog/?s=core+memorySee full shield documenation PDF here:https://jussikilpelainen.kapsi.fi/wordpress/?p=213Also, great explanation and demonstration:

author: pqass
author_rank: Super Contributor
timestamp: March 04, 2022, 09:21:11 pm
content: Just by looking at a close up of the picture, it seems that someone went at the outer pads with a grinder. You'll need to clean that up before you can determine which pads on opposite edges (I'm assuming) are connected. And at each of the corners it appears there are two loops (4 pads) for sense and inhibit. If there is another set of unconnected pads on the reverse, then it looks like you've got 642*4*2 or 4096 bytes total; each quad is a 4k bits.

author: CaptDon
author_rank: Super Contributor
timestamp: March 05, 2022, 02:02:04 pm
content: Seeburg used a toroid magnetic core memory in the older jukeboxes. They called the device the 'Tormat' and it was read out using a voltage pulse of around 100 volts pulsed at each physical record location as the mechanism moved from end to end. The 'letters' selection formed the 'rows' in conventional thinking and the numbers formed the column selection. Such as when you selected the song at B9 or D2. They could remember the selections for years and it was basically non-volatile during power fail!! B.T.W. you could take a 'D' cell and spark it across the sense connector (It was a shielded RCA type) and 'load' the tormat and cause it to play EVERY song. Opposite polarity would clear the entire memory.