Ahhh, core memory, the choice of Apollo Guidance Computer.
CuriousMarc YouTube channel is following the resurrection of an AGC,
Tom.... 
(Yes I am a grandad..)
First I've ever seen such a thing. Pretty cool.
I have a long time before I'm a grandpa though.
Fascinating. But he did not explain how (if it is possible) to detect whether a core contains a 1 or 0 without changing its state.
...R
HI,
There are quite a few of those instruction films on YouTube about the Apollo program and about core memory.
They had a ROM and a RAM version, the RAM version used all those coils and sense wires through the core.
The ROM version was much simpler, but basically impossible to edit, it was true FIRMWARE. The code of 1's and 0's was mechanically woven through the cores, each core having a pickup winding.
There is an Arduino presentation on Youtube playing with some core RAM.
Tom..
OMG, first computer I maintained had 32k core memory and line printers used core memory for data storage 1k.
Good old days.
Robin2:
Fascinating. But he did not explain how (if it is possible) to detect whether a core contains a 1 or 0 without changing its state....R
IIRC, read is destructive, and the value read back must then be rewritten.
AWOL:
IIRC, read is destructive, and the value read back must then be rewritten.
EXTREMELY VOLATILE MEMORY... :o :o :o :o
AWOL:
IIRC, read is destructive, and the value read back must then be rewritten.
Correct. And the real limit to the speed of computers with core memory.
Paul
I honestly didn't expect this many people to be interested....
if that was then and this is now. What's next I wonder?? In the terms of logic.
LandonW:
I honestly didn't expect this many people to be interested....
if that was then and this is now. What's next I wonder?? In the terms of logic.
I think what is fascinating about it is that it took men to the moon and even an old 286 clunker had more power and memory.
LandonW:
I honestly didn't expect this many people to be interested....
if that was then and this is now. What's next I wonder?? In the terms of logic.
Well, I learned programming on a 1k word, 32 bits, with rotating magnetic drum memory. Monroe monrobot desk computer. Paper tape i-o plus IBM typewriter (before selectric).
All machine language. Then went to IBM 1401 with real core memory.
I once scrapped a German made calculator that used core memory. Fascinating thing!
Paul
I often wondered if it was possible to hear a frame of core memory in operation.
However, they usually necessarily operated in noisy (132 column drum line printers, tape drives, washing machine-sized disk drives, air-con...) environments, so I never got the chance to find out.
TomGeorge:
I think what is fascinating about it is that it took men to the moon and even an old 286 clunker had more power and memory.
I recall (from very long ago) a presentation about the Apollo missions. There was a ring that appeared like a spacer or gap filler between the top of stage1 and the bottom of stage2. It got thrown away when stage1 was jettisoned. According to the presentation that "spacer" contained a complete IBM360 which was responsible for launch stability.
This was at a time when college students were using punch-cards to run assembler programs on the college IBM360 which was treated like the Holy Grail.
...R
Are there any pros to core logic over transistor based logic?
LandonW:
Are there any pros to core logic over transistor based logic?
LandonW:
Are there any pros to core logic over transistor based logic?
Certainly! They don't loose their settings when power goes off. And battery backup is not necessary.
Paul
Robin2:
I recall (from very long ago) a presentation about the Apollo missions. There was a ring that appeared like a spacer or gap filler between the top of stage1 and the bottom of stage2. It got thrown away when stage1 was jettisoned. According to the presentation that "spacer" contained a complete IBM360 which was responsible for launch stability.This was at a time when college students were using punch-cards to run assembler programs on the college IBM360 which was treated like the Holy Grail.
...R
The instrumentation ring was much further up the stack (just below the LM, I think), was built by IBM, but was only four feet deep, so I doubt it had much of a 360 in it.
AWOL:
The instrumentation ring was much further up the stack (just below the LM, I think), was built by IBM, but was only four feet deep, so I doubt it had much of a 360 in it.
I apologise for my poor memory.
It may have only been 4 feet deep but it had a large circumference so I suspect the available volume was significant - I'm assuming all the stuff was laid out around the circumference to keep the centre clear.
...R
LandonW:
I honestly didn't expect this many people to be interested....
if that was then and this is now. What's next I wonder?? In the terms of logic.
Quantum entanglement and using that in computing. Both are NOT logical, but seem to be useful!
Paul
AWOL:
I often wondered if it was possible to hear a frame of core memory in operation.However, they usually necessarily operated in noisy (132 column drum line printers, tape drives, washing machine-sized disk drives, air-con...) environments, so I never got the chance to find out.
That reminds me about wearing hearing protection while doing line printer maintenance
95+db and breathing paper dust. 