Core memory emulator using non volatile ram.

Sent from Mail for Windows 10 From: allison via cctech Sent: 16 December 2018 03:08 To: cctech at classiccmp.org Subject: Re: Core memory emulator using non volatile ram. On 12/15/2018 01:01 PM, Guy Sotomayor Jr via cctech wrote: My call on this is that cmos static ram 4Bit wide does the job well I have 32K of it in my PDP-8 to get past possible failure of hard to find and get core.? A Panasonic BR-1 lithium cell has enough capacity at the measured drain for about 6-7 years and the Dallas power management chip makes it a non hack.? Flash, EEprom and Magnetic FRAM and MRAM) types have many unacceptable properties for a random access read write memory.? It makes no difference to the PDP8(ILEFMA) that read is not destructive as it will write back as needed anyway. There is a design on the 'net for using CMOS ram in a straight forward buildable array for Omnibus with battery back up that is fine.? Don;t get wraped around the axle about RMW as any sufficiently fast ram can do that without wearout.? And compared to core it doesn't take much speed. EEprom and Flash work fine for read mostly disks or disk simulators. Allison Sheesh!! Well what a response. This stems from my (so far) successful major over haul of my PDP-8/e. I found one failed 7474 and one failed 8881 ? replaced and now working. I think I have the rim loader toggled in and will attempt to send a paper tape image from Hyperterm Strangely I do have at least three genuine complete 4k memory sets. However I began to think would it be possible to create a close copy of an 8/e out of modern parts. As you all know I make front panels so that?s not a problem. I did manage to copy my (distorted) bezel in resin. A friend has been able to 3D print toggle switch leavers that fit and work. Vince Sylngstat has done a console board PCB layout. Power supply clearly not a problem. So what?s left? Case? Well I have one of those and I suspect a sheet metal shop would not have a problem Finally the big one ? Omnibus and the connectors its made from. A 3D printing candidate? I?m going to autopsy a busted connector and see how they are constructed inside. Objectives The basic board set as original. M8300, M8310, M8320 etc. Same form factor Plug compatible ? but board contents can differ from original The idea is replace one item at time until you no longer have any DEC parts. Yup a FAKE-8 I may even need a label ?No part in this PDP-8/e computer was manufactured by digital equipment corporation? Rod Smallwood