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GE-115 Emulator
An Emulator of the General Electrics GE-115 computer
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cp06 ch.087 "ARITHMETICAL UNIT, CONCENTRATOR" (dwg 14013 0651): the mode block in the sheet's bottom-left corner, nine gates turning the three command lines CI45/CI46/CI47 into the function code the concentrator consumes. More...
Functions | |
| SIG (CI451) | |
| SIG (CI461) | |
| SIG (CI471) | |
| SIG (CI45D) | |
| SIG (CI46B) | |
| SIG (CI47B) | |
| SIG (UCOA1) | |
| SIG (UCO21) | |
| SIG (UCO2A) | |
| SIG (UCO4A) | |
| SIG (UCO41) | |
| SIG (UCO0A) | |
| SIG (UCO01) | |
| SIG (UCO1A) | |
| SIG (UCO11) | |
| SIG (CI50B) | |
| SIG (UZE71_enabled) | |
| SIG (UZE81_enabled) | |
cp06 ch.087 "ARITHMETICAL UNIT, CONCENTRATOR" (dwg 14013 0651): the mode block in the sheet's bottom-left corner, nine gates turning the three command lines CI45/CI46/CI47 into the function code the concentrator consumes.
Transcribed gate by gate; see docs/transcriptions/ua-function-decode.md for the wire-level reading and the resulting table.
Two entries of that table are DEGENERATE, and provably so rather than for want of tracing: CI46 reaches only gates 32 and 27, and enters the code as CI46 + CI47, which saturates whenever CI47 is set. So XOR and OR share a code, and so do decimal and binary subtract. The latter is the expected shape for BCD – subtraction is addition of the ten's complement, so only decimal ADD needs a line of its own (UCO01), and the decimal correction rides on CI50 gating carry propagation to a single quartet.
1.9.8