rcornwell
B5500, I701, I704, I7010, I7070, I7080, I7090: Remove single UNIT DISABLE
If a simh DEVICE has the DEV_DISABLE flag set AND it has 1 UNIT, there really should never be a UNIT_DISABLE flag bit in the UNIT initializer. The reason for this is that, for many things, the DEVICE name can be used equivalently to represent the single UNIT. What are we trying to achieve here?
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If the DEVICE is disabled, then the unit doesn't exist. That's fine.
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If the UNIT is disabled (if the UNIT_DISABLE flag is present allowing SET
DISABLE) what would that then mean about the DEVICE?
Bob Supnik's thoughts:
The rationale was that the device represents the controller logic, the unit the physical transducer. So you could disconnect or power down a paper tape reader, but its controller logic would still be there and would still respond in some way.
Mark Pizzolato said: If the fidelity to the hardware in simulation really behaved precisely as the hardware worked, maybe, but I doubt that this has been a design goal. Even if it had been a design goal, I see 2 issues: a) it would seem that it would have been impossible to produce exactly the failure details that real hardware did without a crazy amount of side by side testing. b) What good would be having a broken device like this connected to a simulated system?
