36
The interface supports the
BOOT
command to load an absolute binary paper tape image. The
BOOT PTR
command is equivalent in hardware to setting the S register to select and configure the HP 12992K boot loader
ROM, pressing the IBL button to copy the ROM into memory, and pressing the PRESET and RUN buttons to begin
execution. The S register is set as follows:
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
0
0
0
0
PTR select code
0
0
0
0
0
0
Loader execution ends with one of the following halt instructions:
•
HLT 11 — a checksum error occurred; A = calculated value, B = expected value.
•
HLT 55 — the load address would overlay the ROM loader.
•
HLT 77 — the end of tape was reached with a successful read.
The paper tape reader state contains these registers:
Name
Size
Radix
Description
BUF
8
8
Input data buffer
CTL
1
2
Control flip-flop
FLG
1
2
Flag flip-flop
FBF
1
2
Flag buffer flip-flop
TRLLIM
8
10
Trailing null limit
POS
32
10
Paper tape image file position
TIME
24
10
Time from I/O initiation to interrupt
The TRLLIM register specifies the number of nulls to supply as paper tape trailer when the end of the tape image
file is reached. If input is attempted when TRLLIM is set to zero or the count is exhausted, the reader will hang.
The POS register specifies the current file position of the next data byte to read. Setting POS to 0 rewinds the
attached tape.
4.4 12597A-005 Tape Punch Interface with One 2895 Paper Tape Punch
The 12597A-005 Tape Punch Interface is an 8-bit duplex register card that connects the HP 2895A/B Tape Punch
to the HP computer family. The 2895 is an eight-level paper tape punch capable of punching at a rate of 75 bytes
per second.
The 12597A interface contains nine configuration jumpers. These are preset for proper tape reader operation.
The simulation provides one punch unit. Attaching a paper tape image file to the unit simulates loading blank paper
tape into the punch:
ATTACH {-N} PTP <image-filename>
Adding the
–N
(new file) switch clears the contents of the image file if present. Without the
–N
switch, punch output
will be appended to any preexisting image file content. Detaching the image simulates removing the punched tape.
If the host operating system returns an error when writing to the paper tape image file, the simulator will report the
error to the simulation console, e.g.:
HP 2100 simulator paper tape punch I/O error: No space left on device
