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25 lines
898 B
Markdown
25 lines
898 B
Markdown
## Other differences between w11a and KB11-C (11/70)
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### Usage of 11/70 `SYSID` register
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In real 11/70's, the `SYSID` register contained an individual serial number.
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The content of this register may be printed in some reports, but it certainly
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has no effect on the logic of the code running on the system.
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The w11 project uses the `SYSID` to encode the execution environment.
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This allows distinguishing between operation on a real w11 and operation
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in a software emulation under SimH or e11.
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It can be used on test and verification codes to reconcile implementation
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differences.
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Usage of the w11 `SYSID` register
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- the SYSID is divided into fields
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- bit 15: emulator flag (0=w11,1=emulator)
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- bit 14:12: type, encodes w11 or emulator type
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- bit 11:09: cpu number on 11/74 systems
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- bit 8:0: serial number
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- current assignments are
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- w11a: 010123
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- SimH: 110234
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- e11: 120345
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