View unanswered posts | View active topics It is currently Thu Jun 27, 2019 6:14 am

Reply to topic  [ 6 posts ] 
 Some bit-serial machines (and projects) 
Author Message

Joined: Wed Jan 09, 2013 6:54 pm
Posts: 1192
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

Fri Mar 15, 2019 10:48 pm

Joined: Wed Apr 24, 2013 9:40 pm
Posts: 159
Location: Huntsville, AL
Don’t leave out the Elliot Brothers computers. The Elliot 152 is discussed on the forum here.

Michael A.

Fri Mar 15, 2019 11:38 pm

Joined: Tue Dec 11, 2012 8:03 am
Posts: 264
Location: California
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.

_________________ lots of 6502 resources

Sat Mar 16, 2019 5:31 am
Profile WWW

Joined: Wed Jan 09, 2013 6:54 pm
Posts: 1192
Thanks, both! I'd forgotten the Elliott post entirely. It turns out bit-serial ROMs go back to the HP-35 at least:
although I think the CPU is nibble-serial inside. I could be wrong.

Sat Mar 16, 2019 8:18 am

Joined: Mon Mar 18, 2019 10:34 am
Posts: 1
Does it even matter if the CPU is nubble-serial or not in this case?

Tue Mar 19, 2019 2:42 pm

Joined: Wed Jan 09, 2013 6:54 pm
Posts: 1192
(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.)

Tue Mar 19, 2019 3:22 pm
Display posts from previous:  Sort by  
Reply to topic   [ 6 posts ] 

Who is online

Users browsing this forum: No registered users and 1 guest

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group
Designed by ST Software