Reply to post: Re: A couple of potential problems

Wanted: Big iron geeks to help restore IBM 360 mainframe rescued from defunct German factory by other big iron geeks

Dave 32
Coat

Re: A couple of potential problems

It wasn't just that it needed cooling; it needed the temperature to remain constant, despite the rather incredible amount of power that it consumed. For, you see, System/360 systems were based on magnetic core memory, and magnetic core memory is temperature sensitive.

I had a bad experience with an IBM 1403N1 printer, attached to an IBM 2821 control unit, which was based on magnetic core storage, about 30 years ago (Why do I suddenly feel old?). When you switched the 1403N1 and 2821 on in the morning, it quickly overloaded the air conditioning in the room it was installed in, and the temperature went from a chilly 68 degrees F up to about 93 degrees F, at which point, the 2821 would start throwing machine checks (e.g., errors), due to the core memory failing, because of the temperature change. We called in an IBM CE, who walked in, took one look at it, threw his arms up, and screamed "That thing is older than I am!", before he turned and walked out. They finally found an old CE, who knew about the 1403/2821, and he told us that he could calibrate it, and get it working at one temperature, but, as the temperature fluctuated, the core storage would start misbehaving, and causing machine checks. Basically, there was no way we were going to get it to work, without completely reworking the air conditioning system (which wasn't going to happen, since that was in a set of temporary trailers). So, the 1403/2821 was ripped out (They had to take the front door off the hinges, in order to get the 1403/2821 in/out of the building.), and a more modern, smaller, yet faster, printer was installed.

As for the "ICs", the System/360 used SLT (Solid Logic Technology), which were cards containing hybrid integrated circuits. The original idea was to standardize on a couple of SLT cards, and build the system out of combinations of those. Unfortunately, the number of specialized SLT designs grew like crazy, resulting in hundreds, if not thousands of specific SLT card designs.

https://en.wikipedia.org/wiki/IBM_Solid_Logic_Technology

As for the age of the system, it's quite possibly over 50 years old.

I seem to remember that most S/360s required three-phase power, which could be a bit of a problem in most residential installations, although there are (expensive, large, heavy) ways of overcoming that.

Also, the S/360 model 20 was very architecturally different than most of the rest of the S/360 product line. While the rest of the S/360 product line standardized on 32 bit registers, the model 20 used 16 bit registers, and did not have the complete set of registers. I think I remember that the I/O subsystem was also rather radically different. The net result is that it required a specialized operating system.

I'd offer to share my COFFEE program, although, while it's designed for a S/370, it should be fairly easy to port to a S/360 (It's a guessing game to determine who amongst a group of operators is to buy the round of coffee.). It's designed to be IPLed from a card reader, and uses the system console for I/O.

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