35
The Time Base Generator state contains these registers:
Name
Size
Radix
Description
SEL
38
Time base selector
CTR
14
10
Prescale counter for < 1 Hz operation
CTL
1
2
Control flip-flop
FLG
1
2
Flag flip-flop
FBF
1
2
Flag buffer flip-flop
ERR
1
2
Error flip-flop
4.3 12597A-002 Tape Reader Interface with One 2748 Paper Tape Reader
The 12597A-002 Tape Reader Interface is an 8-bit duplex register card that connects the HP 2748A/B Tape
Reader to the HP computer family. The 2748 is a photoreader capable of reading eight-level punched paper tapes
at a rate of 500 bytes per second.
The 12597A interface contains nine configuration jumpers. These are preset for proper tape reader operation.
The simulation provides one reader unit. Attaching a paper tape image file to the unit:
ATTACH PTR <image-filename>
... simulates pressing the LOAD button on the reader’s front panel, loading the paper tape into the reader, and
pressing the READ button.
The interface does not provide status to the CPU to indicate that a tape is not loaded or that the end of the tape has
passed through the reader. Attempting to read under these conditions will cause the reader to hang, as it will in
hardware. Specifying the
SET CPU STOP=IOERR
command will cause a simulation stop if either of these
conditions occur. If the error is corrected, either by attaching the paper tape image file or by rewinding the tape,
then resuming simulation will retry the operation.
If the host operating system returns an error when reading from the paper tape image file, the simulator will report
the error to the simulation console, e.g.:
HP 2100 simulator paper tape reader I/O error: Permission denied
...and the simulator stops. Simulation may be resumed and the operation retried if the problem has been corrected
or with the reader operation incomplete if the problem is uncorrectable.
Device options that may be specified are:
Option
Action
READER
Use a normal paper tape; default
DIAGNOSTIC
Use a continuous paper tape loop
SC=<n>
Set the interface card select code; default is 10
ENABLED
Enable the device; default
DISABLED
Disable the device
The
DIAGNOSTIC
option converts the attached paper tape image into a continuous loop by joining the ends of the
tape. This is used by the High-Speed Tape Reader/Punch Diagnostic (DSN 146200). Setting the
READER
option
returns the tape image to its normal linear configuration.