Category: warstory

/360 Condition Codes

   When IBM brought out the /360 mainframe in 1964, one thing that took some getting your head around was processing Condition Codes.
 Many operations set a “condition code” which indicated the result of the operation and which could be tested by a Branch-On-Condition instruction:
   BC xx,yyyy   =   Branch to yyyy on Condition xx
Part of the problem was syntax – the term “Condition Code” had two meanings:
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        IBM at it’s best
This special system was built specifically for NYSE to report trading data.


Two /360 Model 50s, RPQ’d to function like Model 65s.
  RPQ’d to use Channel-to-Channel to signal each other
  RPQ’d to fetch from LCS

LCS non-volatile memory, configured:
    2megs duplexed
  or 4megs simplex
  or two separate 2-meg units.

  RPQ’d to feed the LCS’s 4-byte memory fetch to accomodate the /360-50’s 2-byte memory fetch. Continue reading