CDC arithmetic
in [Fortran]
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From: robin on 8 Aug 2010 07:45 "Richard Maine" <nospam(a)see.signature> wrote in message news:1jmsnwd.1y8u6r31f3t1oeN%nospam(a)see.signature... | An interesting thing about integer arithmetic operations was that... | there were none - at least none with their own dedicated opcodes. The CDC Cyber had separate op codes for the integer instructions.* Integer 60-bit add/subtract being 36 and 37. Op codes 70 to 77 were the integer add/subtract using one of the 18-bit registers as well as a 60-bit integer register. The floating-point add/subtract/multiply instructions used the op-codes 30 to 35 and mult-div used codes 40 to 45 omitting 43. | You | just used the same opcodes as for floating point, and the hardware | special-cased operands with the 12 high order bits all 0 or all 1. That was only for integer multiply, introduced on the Cyber 70 series. | It | seemed like the machine was designed to crunch floating point numbers, | with integers being a special case. _______________ * The only exception being integer multiply, which used the same op code as float multiply, as I said a few days ago. |