EEVblog #648 - Mailbag

Mailbag Monday
Dave opens his mail, outback Australian style...

Franky's Ebay Store

Ten Essential Skills for Electrical Engineers

WiFi Digital Radio teardown

1970 vintage Magnetic Core Memory!

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[FranLab]

That's a Nywfe!  I have been waiting for years for that one to come up in your vlog Dave. 

[josephcote]

Dave, The ferrite core memory was, to the best of my knowledge, constructed by hand. Women actually weaving the wires through the cores.

We had a substitute instructor in college for a hardware class who had worked on developing these types of memories. One of the problems that he had was heat buildup because of the density.

Running faster needed more voltage which caused more heat. Each plane of cores was one bit of a word, you'd run them in parallel to build whole words. the planes would be built s close as possible to save room.

One experiment in cooling had the memories in a large tube and cooled mineral oil flowing over them to remove the heat. But it kept failing at the same place over and over. What they found was that the flowing oil was making certain beads spin and wear away the insulation from the wires causing a short. Solution was guide vanes in the tube to smooth out the oil flow.

#talesfromthedarkages

[dumbo]

I sitting at home, in the US summer, being sick, and hoping you posted a mailbag to brighten up my day. 

You have have achieved that. Thank you, Dave.

[excession]

Absolutely loved seeing the microscope closeup of the core memory.  They were probably 16 bit words, but may have been more.  I'm sure someone will know.  The Control Data Cyber mainframes had 60bit words, and the core memory in those was quite large -- extended core memory came along later, and the ferrite cores in ECM boards were truly microscopic.

[bepowerification]

omg after a bazillion of mailbag vids I finally found the one introducing the standard everyday use australian knife. yay.

[DJGhostingFish]

27:20 You're referring to this Computer for Apollo

I came across this a long time back. Extremely interesting stuff, and it's interesting to see how far we've come with computers and what-not

[skuula]

That Chinese meter looks like having been made by a serious company or institution, not just cheap mass production. This was at a time when China was struggling hard to get up to date with technologies after decades of political isolation.

[swsephy]

That memory board looks really cool. I've never seen something like that before.

[JerryEricsson]

ahh 1970, I remember it well. Army Basic Training, Advanced training, a short visit home to make a baby with my new wife, and I was off to Vietnam. I recall my first computer, a Commodore 128, when I first got it, I had it in my head that when the computer read from the memory, it could be changed and the entire program had to be written back to the disk. Thankfully my son was there to straighten me out on that.

[PuchMaxi]

Gotta love the Crocodile Dundee quote! :D

[sbalogh]

From the net:
1. In spite of considerable effort, no one successfully automated the production of core, which remained a manual task into the 1970s.
2. But manufacturing it was a delicate job, entrusted mostly to women using microscopes and steady hands to thread thin wires through holes about the diameter of a pencil lead.

[NoMad]

Crocodile Dundee, Monty Python, Beautiful vintage technology... you're hitting ALL the buttons! I laughed out (really) loud at 23:43 (it's 5am on a monday morning). Great video, Dave.

[brainsironically]

Well done to Stephan for the ferrite memory find!  Very cool!

[herbertsusmann]

I used to use and repair Data General 16K magnetic core memory boards when I had a summer job in high school. That was about 1977 or so and RAM was out but the core boards were still in use in lots of machines.  They had MUCH smaller magnetic cores than this one. Very convenient as you could load your test program in the board, then move it to another machine and run it! Didn't loose it's data on power down!

[martinda]

Pause on ''About the Author'',  I love what Barry's dad did with him and that truck, what a lucky lad. Life is all about luck. Hope you all have some soon.

[bits]

For the record, a word of memory is two bytes. In a little-endian machine (e.g. Intel x86) the bytes are read in backwards, in a big-endian machine the bytes are read in in order.

[Screamingtut]

I used to work for Digital Equipment Corp in NYC in 1978 as a Sr Field Engeneer and had a few accounts that had some old equipment that still used that type of core memory but it was 8k-32k for each board I worked on LSI 11/23, PDP 11/34A PDP-11/40, 11/45 11/60 PDP11/70 & VAX 11/780 & VAX 11/750  

[bilzoo]

Love the ferrite core memory. Built a small 4-byte matrix once, couldn't figure out how to drive it. Hoping you make a video about writing/reading to it.

[ebmmdawguy]

The deadpan way in which you opened the package with the knife had me in stitches. Hahaha.

[ocayaro]

Those magnetic core memories were actually woven by hand, thanks to a team of women with steady hands and lots of patience.