38
When a debug log has been established, tracing may be configured by specifying one or more of the reporting level
options:
Option
Reporting Level
CMD
Interface commands
IOBUS
I/O bus signals and data words received and returned
The
CMD
option traces commands executed by the interface. The
IOBUS
option traces the I/O backplane signals
and data received and returned via the interface.
Examples of the trace formats follow:
>>PIF cmd: Control reset
>>PIF cmd: Fence allows lower-priority interrupts
>>PIF cmd: Fence inhibits lower-priority interrupts
>>PIF iobus: Received data 000000 with signals STC
>>PIF iobus: Returned data 000000
Because the PIF is accessed twice for each unprivileged interrupt, systems employing the 12539C Time Base
Generator will generate a large number of debug statements very quickly. In such cases, tracing should be
enabled for the minimum time necessary.
The Privileged Interrupt Fence state contains these registers:
Name
Size
Radix
Description
CTL
1
2
Control flip-flop
FLG
1
2
Flag flip-flop
FBF
1
2
Flag Buffer flip-flop
4.6 12653A Line Printer Interface with One 2767 Line Printer
The HP 12653A Line Printer Interface connects the HP 2767A line printer to the HP computer family. The printer
provides 80-column output at rates from 356 to 1110 lines per minute, depending on the number of columns
printed. It uses a 64-character repertoire (ASCII codes 32 through 95), prints a fixed 60 lines per page, and
automatically skips page perforations. It does not have a vertical format unit (VFU) but will slew to the top-of-form
upon receipt of a form-feed character.
The simulation provides one printer unit. Attaching a text file to the unit simulates loading paper into the printer:
ATTACH {-N} LPS <image-filename>
Adding the
–N
(new file) switch clears the contents of the image file if present. Without the
–N
switch, printer output
will be appended to any preexisting image file content.
Printer output written to the image file is typically buffered by the host operating system’s underlying stream I/O
routines. While it is running, the simulator flushes the file after each printer top-of-form request to permit
convenient inspection of the image file. Stopping the simulator also flushes the file.
If the host operating system returns an error when writing to the printer image file, the simulator will report the error
to the simulation console, e.g.:
HP 2100 simulator printer I/O error: No space left on device