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Some bit-serial machines (and projects) http://anycpu.org/forum/viewtopic.php?f=3&t=581 |
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Author: | BigEd [ Fri Mar 15, 2019 10:48 pm ] |
Post subject: | Some bit-serial machines (and projects) |
We've previously mentioned some serial machines in discussions, and MichaelM has at least one in-progress project. So I thought it might be useful to have a thread to link to those discussions and to talk about bit-serial machines. MichaelM's MiniCPU-S in HDL and in C (mentioned here too.) The LGP-30 from 1956 - just 15 flipflops Olivetti Programma 101 - delay line memory, pretty likely to be a bit-serial machine. Many calculators are nibble-serial. Early machines mentioned in "Faster than thought" by B. V. Bowden Ferranti's 12 bit wonder: the 1968 FM1200 |
Author: | MichaelM [ Fri Mar 15, 2019 11:38 pm ] |
Post subject: | Re: Some bit-serial machines (and projects) |
Don’t leave out the Elliot Brothers computers. The Elliot 152 is discussed on the forum here. |
Author: | Garth [ Sat Mar 16, 2019 5:31 am ] |
Post subject: | Re: Some bit-serial machines (and projects) |
The HP-41 calculator/computer which came out in 1979 and was discontinued 11 years later has a bit-serial data bus even though its Nut processor has lots of 56-bit registers and RAM consists in 56-bit registers too. |
Author: | BigEd [ Sat Mar 16, 2019 8:18 am ] |
Post subject: | Re: Some bit-serial machines (and projects) |
Thanks, both! I'd forgotten the Elliott post entirely. It turns out bit-serial ROMs go back to the HP-35 at least: http://www.pmonta.com/calculators/hp-35/chips via http://www.pmonta.com/calculators/hp-35/ although I think the CPU is nibble-serial inside. I could be wrong. |
Author: | Hullins [ Tue Mar 19, 2019 2:42 pm ] |
Post subject: | Re: Some bit-serial machines (and projects) |
Does it even matter if the CPU is nubble-serial or not in this case? |
Author: | BigEd [ Tue Mar 19, 2019 3:22 pm ] |
Post subject: | Re: Some bit-serial machines (and projects) |
(Welcome, Hullins!) No, it doesn't matter in a deep sense, but a bit-serial memory is saving pins, in this technology, whereas a bit-serial ALU would also save transistors. A nibble-serial CPU is a good choice for a decimal machine: it's progressively harder to do decimal arithmetic as a CPU gets wider. (I'm interested to know whether "operating in a serial-parallel mode" was an unambiguous and well-recognised phrase back in the day. There was a time when memory had to be serial, and the CPU probably was too. Then there was a time when parallel (core) memory made sense, but flip-flops were expensive so a bit-serial CPU made sense.) |
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