Rare IBM Schools Computer 1969

Summary

Hello, I found the IBM schools computer in the IBM Hursley museum. That is the machine you see in those pictures. Next to it was a single sheet quick reference card. That had the full instruction set on it and some operating instructions. That got me interested as there seemed to be enough information on that sheet to have a go at making a replica. After some research I found a few documents and even photos of it being used in a school. There was enough to create a replica using a RP Pico, some buttons and a small OLED display. That is shown here: The original was designed and built in Hursley in the UK and was, I think, based on the IBM360 type of SLT circuitry. I asked the museum curators if they would open the museum machine with a view to maybe getting it running again or replicating at the hardware level. They did open the machine and found it was actually just case. There was no functioning hardware inside at all, even the keyboard is a non functional panel. It seems that this machine was just a mechanical prototype of some sort. The architecture of the computer is odd by todays standards, and very much aimed at mathematics. It runs in BCD, so decimal, has 32 bit registers, apart from some double length registers of 64 bits and 200 words of core store. The floating point instructions are actually coded in the machine language of the ‘processor’ and stored in one half of core store. they are run as normal instructions but a branch to core is made to run the actual code (extracodes). This does allow custom instructions to be created to replace the standard floating point instructions, or add to them. There is an example of this in one of the documents I found. i did manage to collect documents about the machine, there was the original quick reference sheet, and a paper about the unit that describes it’s architecture in detail was fairly easy to find. I actually managed to buy a paper copy of that document on ebay. There are some patents that describe aspects of ...