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LWN.net Weekly Edition for May 16, 2013
A look at the PyPy 2.0 release
PostgreSQL 9.3 beta: Federated databases and more
LWN.net Weekly Edition for May 9, 2013
(Nearly) full tickless operation in 3.10
Our editor's early computer
Posted Jul 9, 2009 19:38 UTC (Thu) by corbet (editor, #1)
Posted Jul 9, 2009 19:46 UTC (Thu) by felixfix (subscriber, #242)
The 6600 had a bug which the 7600 might have had too. Instructions were 15 or 30 bits, with 6-bit opcode and three 3-bit register numbers. The conditional instructions used one of those register fields as the condition number (zero, non-zero, negative, plus, nan, etc) and if that happened to be the same number as a busy register, the instruction would stall until that register was done, even if not involved in the instruction itself.
Thanks for bringing back some fun memories.
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