HP 3000 III Series Manual page 148

Machine Instructions and Stack Operations
ready (bit = "0"), the content of the device controller's Status
Register is pushed onto the stack and the Condition Code is set
to CCG. If the device controller does not respond to the readi-
ness test, the Condition Code is set to CCL and the instruction
is terminated.
Special opcode: 10
Indicators: CCL = non-responding device controller
CCE = device ready
CCG =device not ready
Traps: STOV, MODE
This is a privileged instruction.
SIO Star t I/O
K
The SIO instruction expects the absolute starting address of an
I/O program to be on the TOS, and a device number to be in the
stack at S-K. The instruction first checks if the device is
ready for an SIO by checking bit 0 of the device controller's
Status Register. Bit 0 is the "SIO OK" bit. If it is ready (bit
= "1"), the TOS is stored into the first location of the DRT en-
try for the device specified at S-K; an SIO command is then issu-
ed to the device controller to begin execution of its I/O pro-
gram. If the device is not ready (bit 0 of the device status =
"0"), the content of the device controller's Status Register is
pushed onto the stack and the Condition Code is set to CCG. If
the device controller does not respond, the Condition Code is set
to CCL and the instruction is terminated. If the device is
ready, the TOS is deleted and the Condition Code is set to CCE.
Instruction Commentary 8.
Special opcode: 07
Indicators: CCL = non-responding device controller
CCE = device ready
CCG = device not ready
Traps: STUN, STOV, MODE
This is a privileged instruction.
TIO Test I/O
K
This instruction expects a device number to be given in the stack
at S-K. TIO obtains a copy of the device status word from the
device controller, pushes it onto the stack, and sets the Condi-
tion Code to CCE. If the device controller does not respond, the
Condition Code is set to CCL and the instruction is terminated.
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