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I'm glad someone reads my footnotes :-). About the rentals - most customers rented instead of buying. This had a huge effect on computer companies. Starting a c

by kens 12y ago

I'm glad someone reads my footnotes :-). About the rentals - most customers rented instead of buying. This had a huge effect on computer companies. Starting a competitor was extremely capital intensive since you had to build the computers up front and then you got revenue monthly, rather than from big sales. Rentals also made IBM conservative since they didn't want to introduce a new machine that would obsolete all the old ones they were still renting out. As for the design book, I only recommend it about 50% - it has a lot of academic theory that HN readers may find uninteresting. It also goes into great detail of the architecture of IBM buildings. Not to discourage you but just set expectations.

Shivetya 12y ago
We employ z, i, and p, series systems from IBM currently. The biggest costs these days have become licensing software and site costs; power, cooling, site to site comm, and space. The number of languages used across all platforms is varied and well represented. There will always be a lot of business use for large hardware and even languages I thought long past their prime have had enough enhancements they blend the best of the old coding with the newest.
CamperBob2 12y ago
Just curious, what's the MTBF of those two machines at the museum? Hard to believe those those germanium transistors aren't all leaky as heck by now.
- kens 12y ago
  There's always something to repair - the 1401 restoration team (consisting of retired IBM engineers) is at the museum every Monday doing maintenance. The computers work most of the time, but the card readers take a lot of adjustment and they are still trying to get all the tape drives operational. One nice thing about the 1401 is the gates swing open for easy access to the circuitry for hardware debugging. This picture from Wikipedia shows what debugging looks like, with an oscilloscope hooked up to the 1401: https://en.wikipedia.org/wiki/IBM_1401#/media/File:IBM_1401_signal_tracing_at_CHM.agr.jpg https://en.wikipedia.org/wiki/IBM_1401#/media/File:IBM_1401_... The museum has a cabinet full of SMS cards, so if they find a problem, in most cases they can swap out the bad card. The card can then be fixed, usually by replacing the bad transistor. At the start, fixing all the bad transistors was a huge problem, which is why it took the restoration team 10 years to get the 1401 running. The German machine in particular was a problem because it had been stored in an unheated garage for a decade, so there was a lot of corrosion. Some of the transistors would literally fall apart if you touched them. (This is what I'm told - I wasn't part of the restoration.) The other complication with the German machine is it included the "overlap" feature, which allowed overlapping of reading, punching, and computation for increased performance. A nice feature, but it made it much, much harder to figure out what was wrong.

by kens 12y ago

Shivetya 12y ago

We employ z, i, and p, series systems from IBM currently. The biggest costs these days have become licensing software and site costs; power, cooling, site to site comm, and space. The number of languages used across all platforms is varied and well represented. There will always be a lot of business use for large hardware and even languages I thought long past their prime have had enough enhancements they blend the best of the old coding with the newest.

CamperBob2 12y ago

Just curious, what's the MTBF of those two machines at the museum? Hard to believe those those germanium transistors aren't all leaky as heck by now.

kens 12y ago
There's always something to repair - the 1401 restoration team (consisting of retired IBM engineers) is at the museum every Monday doing maintenance. The computers work most of the time, but the card readers take a lot of adjustment and they are still trying to get all the tape drives operational. One nice thing about the 1401 is the gates swing open for easy access to the circuitry for hardware debugging. This picture from Wikipedia shows what debugging looks like, with an oscilloscope hooked up to the 1401: https://en.wikipedia.org/wiki/IBM_1401#/media/File:IBM_1401_signal_tracing_at_CHM.agr.jpg https://en.wikipedia.org/wiki/IBM_1401#/media/File:IBM_1401_... The museum has a cabinet full of SMS cards, so if they find a problem, in most cases they can swap out the bad card. The card can then be fixed, usually by replacing the bad transistor. At the start, fixing all the bad transistors was a huge problem, which is why it took the restoration team 10 years to get the 1401 running. The German machine in particular was a problem because it had been stored in an unheated garage for a decade, so there was a lot of corrosion. Some of the transistors would literally fall apart if you touched them. (This is what I'm told - I wasn't part of the restoration.) The other complication with the German machine is it included the "overlap" feature, which allowed overlapping of reading, punching, and computation for increased performance. A nice feature, but it made it much, much harder to figure out what was wrong.