37
...and the simulator stops. Simulation may be resumed and the operation retried if the problem has been corrected
or with the punch operation incomplete if the problem is uncorrectable.
Device options that may be specified are:
Option
Action
SC=<n>
Set the interface card select code; default is 12
ENABLED
Enable the device; default
DISABLED
Disable the device
The paper tape punch state contains these registers:
Name
Size
Radix
Description
BUF
8
8
Output data buffer
CTL
1
2
Control flip-flop
FLG
1
2
Flag flip-flop
FBF
1
2
Flag buffer flip-flop
POS
32
10
Paper tape image file position
TIME
24
10
Time from I/O initiation to interrupt
4.5 12620A/12936A Privileged Interrupt Fence
The Privileged Interrupt Fence (PIF) is used in DOS and RTE systems to provide privileged interrupt capability.
The PIF is installed in the I/O backplane to separate privileged from unprivileged devices by controlling the interrupt
priority chain signal (PRL) to lower-priority devices. The privileged cards located below the fence are allowed to
interrupt the operating system and the service routines of the unprivileged cards located above the fence.
Privileged devices employ specially written device drivers that bypass the operating system during interrupts. This
provides very fast interrupt service time.
HP produced two PIF cards: the 12620A Breadboard Interface for the RTE operating systems, and the 12936A
Privileged Interrupt Fence Accessory for DOS. They behave quite differently and are not interchangeable.
Device options that may be specified are:
Option
Action
12620A
Use a 12620A RTE fence; default
12936A
Use a 12936A DOS fence
SC=<n>
Set the interface card select code; default is 37
DEBUG=<option>
Enable tracing
NODEBUG
Disable tracing; default
ENABLED
Enable the device; default
DISABLED
Disable the device
Device configuration may be displayed with the following commands:
Command
Action
SHOW PIF TYPE
Display the current fence type
SHOW PIF DEBUG
Display the current debug state