All Questions
Tagged with instruction-set besm-6
4
questions
11
votes
6
answers
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Was there a Western computer with blatantly missing instructions in the instruction set?
In the BESM-6, there is an instruction (045) to add index registers, but not to subtract them, however, there is a nearby unused opcode 047, which is made synonymous to 045 (in fairness, that's true ...
- 19.4k
8
votes
1
answer
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How can floating point addition be so slow on a BESM-6?
In the BESM-6 technical manuals — for example, in the ALU description, page 4 — there is a table specifying min/max/average instruction latencies in clock cycles (the last 3 columns; the ...
- 19.4k
10
votes
5
answers
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Which CPUs had instructions leaving data registers in an unspecified state?
When an ALU performs a floating point division operation using the non-restoring or the SRT algorithm, it maintains the current value of the "remainder" (in quotes, because it is not a true ...
- 19.4k
11
votes
2
answers
1k
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What is the purpose of the ω register of the БЭСМ-6?
This page describing the БЭСМ-6 instruction set refers to a value called ω, which is stored inside a Mode Register. It appears to be set by certain kinds of instructions, so that ω can tell you which ...
- 39.3k