
Repairing a 1960s mainframe: Fixing the IBM 1401's core memory and power supply - fernly
http://www.righto.com/2017/12/repairing-1960s-mainframe-fixing-ibm.html#fnref:aqw
======
AdamJacobMuller
I've actually seen this machine in person, I have a punch card with my name on
it somewhere that it printed out.

As someone who missed this era of computing entirely, but was quite familiar
with it, it was very awesome to see in person. One thing that I really wasn't
expecting was the smell in that room. I spend a lot of time in data centers
but the room at the CHM with the 1401 smelled more like a machine shop than
any data center I've ever been in.

The CHM, in general, was awesome to visit, but definitely go on a day when you
can get the 1401 demo.

~~~
djsumdog
The owners manual about keeping things oiled and preventing cards from binding
(it's read in a mellow British accent in the music piece I mentioned in
another comment). I never thought about it until now, but I guess being around
this machine would be more like working on a car or factory equipment than
what we would consider a data center machine.

------
djsumdog
Whenever I hear about the IBM 1401, I think back to Jóhann Jóhannsson IBM 1401
symphony. It's in five movements and uses sounds generated from an actual
1401, as well as very interesting readings from the user's manual. It's a
truly amazing work:

[https://www.youtube.com/results?search_query=IBM+1401+Jóhann...](https://www.youtube.com/results?search_query=IBM+1401+Jóhann+Jóhannsson)

------
blt
Kind of mind-blowing that this machine needed two big TO-3 package transistors
to drive 4000 bits of memory. Nowadays you could probably power a few dozen
Raspberry Pi's with that amount of current.

~~~
kens
Remember that the core memory is magnetizing metal rings in microseconds, so
it takes substantial current pulses. But not as bad as vacuum tube computers -
I've been working with an IBM 705 tube module from the 1950s and you can feel
the heat coming off it.

~~~
fuzzfactor
With music amplifiers basically a couple TO-3's with nominal passive heatsink
can output the equivalent 50 watts of a pair of 6L6 vacuum tubes.

The tubes run hotter because of the always-on heated cathode which is not
needed for solid state amplification.

BTW still have a couple Diablos and a DEC drive, for parts, that could use a
home.

Also an HP1000 in a full rolling rack the size of a refigerator, plus a VAX
4000, it's a mini-fridge. These are in good shape.

~~~
kens
Fuzzfactor, can you contact me (ken.shirriff@gmail.com) about the HP 1000? I
found someone who is interested in it.

------
nerdponx
Out of curiosity, why couldn't they just replace the bad inductor, instead of
swapping out the board entirely?

~~~
kens
I replaced the inductor with one from a different bad board, but it took a
while to identify the inductor as the problem with the board. Some people
wanted to get the system running right away, and there were spare boards
around.

------
the-dude
Please remove the anchor from the link.

~~~
kens
I've changed the anchor in the article page, so the link anchor will now be
ignored.

~~~
monochromatic
Well that works too.

Love your website, by the way.

