This document has a chart listing the minimum RAM requirements for various versions of the firmware (which IBM calls Licensed Internal Code). The versions I have access to are A5 and B5, with the A5 versions formatted for the 1.2MB drive that came in the machine. Version A5 requires 2MB of RAM.
My controller (model 51R) has a base configuration of 1MB of RAM and a single 1.2MB diskette drive. Unless I find diskettes for version A4, the firmware won't fit inside the paltry RAM installed on this model.
There were two revisions of the planar (motherboard) in a model 51R, one has 512KB onboard and the other had 1MB onboard. For the machines that have the 512KB planar, a plug-in card was added to bring the total RAM up to 1MB.
Since I don't know the history of my machine, I had to do a bit of disassembly to figure out which revision I have. Turns out it was the 9021-03 planar, which has only 512KB of onboard RAM. I don't see an additional card that might host the other 512K. Frankly, I don't see a slot into which I might plug an additional board, such as a 2MB card giving me either 2.5 or 3MB total.
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| 3174 planar (motherboard) |
I have ordered a 2MB plug in module, which should bring my machine up to a level that can support the firmware. I am taking a bit of a risk since I don't see where or how this might be added to the machine, but I have attempted to contact someone whose comment four years ago to some reseller indicated that the reseller updated a 51R to 2.5MB, which is what I hope to accomplish.
I thought of you and your DSKY project this evening. I caught about the last half of a program on my local PBS station called "8 Days to the Moon and Back". I'm sure a lot of it was re-enacted or CG, but there were some all too fleeting shots of the DSKY in operation in Apollo 11. There was also at least one mention of one of its verbs and nouns, along of course with the infamous 12xx error indications.
ReplyDeleteTranquility Base has such a nice sound to me!