PC Elite Reference
Technical Details
controller. All this done by writing command to the aux mode
register. If only there were a few more commands!
IFC InterFace Clear.
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The IFC control line is controlled by the aux mode
register. When the computer is acting as the system controller, ie
ALL THE TIME in normal use, the IFC line may be asserted by
writing 01bh to the aux mode reg. To return the IFC line high
write 013h to the aux mode register. In practice, this IFC line
should only be toggled low for short time and then returned
high. The standard pulse time is a minimum of 100 micro
second.
In normal use IFC should be held HIGH. Only pulse IFC
when you need to assert control of the bus due to a device crash
etc.
REN Remote ENable.
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The REN line is controlled by the aux mode register.
When the computer is acting as the system controller, ie ALL
THE TIME in normal use, the REN line may be asserted by
writing 01fh to the aux mode reg. To return the REN line high
write 017h to the aux mode register.
ATN ATteNtion.
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The IEEE ATN line is controlled by the aux mode register.
When the computer is acting as the controller in charge, ie ALL
THE TIME in normal use, the ATN line may be asserted by
writing 011h, 012h or 016h to the aux mode reg. To return the
ATN line high write 010h to the aux mode register.
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Chapter 3
