Mask all Interrupts and then Interrupt

JArchibald at aol.com JArchibald at aol.com
Thu May 25 00:56:12 UTC 2000


=> 5/24/00 7:51:45 PM EDT, tim at sumeru.stanford.edu =>
<< Strange OpCodes: MII: Mask all Interrupts and then Interrupt >>

Tim--

In the ancient (and strange) world of early System/360 development and 
marketing, there was very little (as in 'nothing') to run on the available 
machines to convince any conceivable buyer that these machines did anything.

A reputed facility (details must be sketchy here, to protect reputations) was 
developed known informally as "The Demonstration Compiler". It has such 
memorable instructions as:
    I:  Read cards repeatedly.
    II: Print. <basically whatever was in memory starting at address 0, in 
hex>
    III:    Spin tapes rapidly. <i.e., forwards and backwards>
along with control instructions to generate timed loops of such things.

This last instruction was quite important. 7090 users knew that machines that 
were working hard used their tapes a lot (earliest S/360 models didn't have 
the disk packs -- and potential buyers would have been unfamiliar with them 
anyways).

To a better world!
Cheers,
Jerry.
____________________________

Jerry L. Archibald
systemObjectivesIncorporated
____________________________





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