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 The Digital Scientific META-4, from 1969 
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Joined: Wed Jan 09, 2013 6:54 pm
Posts: 1277
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This jumped out at me, as a new meaning to the idea of disassembling microcode:
Quote:
For the back end machine we chose a very interesting microprogrammable minicomputer, the Digital Scientific META-4, a new machine (1969). By the time our META-4 arrived my simulation was finished and we were well into the code on the 1108.

Because I love hardware I immediately latched onto the META-4. I decided to implement some additional instructions in microcode, ones I thought would speed up database processing. To microcode the META-4 one first disassembled the microcode store, which consisted of a sandwich of glass plates with small metal foil squares glued on to implement the codes. The reason for this arcane arrangement was because the macrocode store needed to be very fast, and core memory and other read-only memory implementations were too slow. After disassembling the store, one removed or added metal squares corresponding to the bits of the desired instructions. The machine came with a generous supply of little squares, conveniently provided with an adhesive backing.


From the very interesting career retrospective blog of Rudd Canaday, the fourth and little-known member of the team who invented UNIX.

Next paragraph:
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It turned out that the microcode idea was not a good one. My special instructions did not make any perceptible difference in the speed of our system. However, I had fun.


More about the machine here.

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Thu Jun 15, 2017 12:50 pm
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Joined: Tue Jan 15, 2013 10:11 am
Posts: 114
Location: Norway/Japan
Thanks for posting that. A very interesting way of implementing microcode.. with bits of metal. Makes a lot of sense, if the only alternative was core memory.
(Unfortunately I can't look into the google book link, I get an error message saying that I've probably reached my limit for looking at that book.. which I have never looked at before.)


Fri Jun 16, 2017 7:21 am
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Joined: Fri May 08, 2015 6:22 pm
Posts: 61
Just some Google oddness, clicking the small icon of the book (at the mentioned error page) seems to fix the glitch and bring up the content.


Sat Jun 17, 2017 12:52 am
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Joined: Wed Jan 09, 2013 6:54 pm
Posts: 1277
Here's a bit more from the book:
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Meta-4-p157.png [ 76.48 KiB | Viewed 3146 times ]


Sat Jun 17, 2017 5:53 am
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