Input From Port; Output To Port; System Boot; Load Os And Return To Debug - David Griffith P112 Assembly And Operation Manual

5.8

Input from Port

The command
I <port>
will read and display a single byte from the given port address. A 16-bit address
is allowed, and the high-order bits will be set correctly. For an 8-bit address,
they will be zero.
5.9

Output to Port

The command
O <port> <data>
will output the byte <data> at the given port. The address is set up as for the
"I" command.
5.10

System Boot

Z <drive>
The <drive> parameter may take values of 1, 2, or 3, defaulting to 1. A
parameter of 1 will start a boot from the first floppy drive (referred to as "drive
0"). A parameter of 2 will start a boot from device 0 on an attached SCSI
interface. A parameter of 3 will start a boot from a GIDE-type IDE interface.
Simply typing Z will attempt a boot from each of the three devices, Floppy,
SCSI, and GIDE, in that order. If the floppy boot fails, it will attempt a SCSI
boot. If that fails, a GIDE boot will be attempted. This sequence will repeat
ten times before declaring an error.
5.11

Load OS and return to DEBUG

L <drive>
This is the same as Z above, except that control is returned back to DEBUG
instead of running what was loaded.
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