Tape Operation Codes
TRW The tape unit designated by the digits in positions 1
and 4 is instructed to rewind its tape. The unit is ef-fectively disconnected from the system until the rewind operation is completed, at which time it again becomes available to the stored program. The ready light on the unit turns off while the tape is rewinding, and turns on again when the unit is again ready for use.
EXAMPLE: To rewind tape unit 0 on channel 4 and make it again available to the stored program after the rewind operation is completed:
SOl 23 4 5 6789
±84 00 0 0 xxx2
Sign can be either plus or minus. Positions 6-8 can contain any digits.
TIMING: An entire 2400-foot reel of tape takes about 1.2 minutes to rewind on a 729 II Unit; .9 minute on a 729 IV Unit.
The tape channel is released and made available to the stored program after 35 milliseconds.
AUTOCODER EXAMPLE (Figure 143): The assembled in-struction is:
SOl 23 4 5 6789 +84 00 0 0 0002
Tape Rewind Unload
xxx3 TRU
This code is the same as TAPE REWIND except that the tape unit is not available to the system after the rewind operation is completed. It cannot be used again by the stored program until the operator makes it available.
Label OPERAND' Basi c Autocoder---J Autocoder
25 30 35 40 45 50 55 601 65 70
FIGU:" 142.
25 30
Label OPERAND
35 40 45
Basi c Autocoder---J
50 55 601
Autocoder
65 70
FIGURE 143.
Label OPERAND Basi c Autocoder ~ Autocoder
25 30 35 40 45 50 55 601 65 70
FIGURE 144.
Label OPERAND Basic Autocoder~ Autocoder
25 30 35 40 45 50 55 601 65 70
FIGURE 145.
EXAMPLE: To rewind tape unit 5 on channel 1 and make it unavailable to the stored program at the completion of the rewind operation:
SOl 23 4 5 6789
±81 00 5 0 xxx3
Sign can be either plus or minus. Positions 6-8 can contain any digits.
TIMING: Same as TAPE REWIND.
AUTOCODER EXAMPLE (Figure 144): The assembled in-struction is:
SOl 23 4 5 6789 +81 00 0 0 0003
Tape Record Backspace
xxx4 TRB
The specified tape unit backspaces the tape one record (tape records are defined as separated by Inter-Record Gaps). If the tape backspaces over a segment mark or tape mark, this is considered as one record. If the tape is at load point at the time this command is given, no tape motion takes place; the instruction is the equiva-lent of NOP.
EXAMPLE: To backspace tape unit 2 on channel 2 one record:
SOl 23 4 5 6789
±82 00 2 0 xxx4
Sign can be either plus or minus. Positions 6-8 can contain any digits.
TIMING:
729 II 729 IV
Milliseconds, after a read operation 46.4
+
CN32.6
+
CN729 II 729 IV
After a write operation Add 7.5 milliseconds to above Add 5.0 milliseconds to above C = Milliseconds per character
N = Number of characters in the tape record.
AUTOCODER EXAMPLE (Figure 145): The assembled in-struction is:
SOl 23 4 5 6789 +81 00 4 0 0004
Tape Segment Mark Write
xxx5 (P)TSM
This instruction causes a tape segment mark (CA8421) to be written as a one-character record on the tape. The segment mark is automatically provided for this opera-tion; it doesn't need to be in storage.
This instruction can be used to initiate a normal-priority signal (+ sign in the operation code).
EXAMPLE: To write a segment mark on tape unit 3 on channel 2 and to signal for normal-condition priority:
SOl 23 4 5 6789 +82 00 3 0 xxx5
Positions 6-8 can contain any digits.
TIMING: The equivalent of writing a single-character record:
729 II, High Density 10.8 + .024 milliseconds 729 II, Low:er Density 10.8 + .067 milliseconds 729 IV, High Density 7.3 + .016 milliseconds 729 IV, Lower Density 7.3 + .044 milliseconds AUTOCODER EXAMPLE (Figure 146): The assembled
in-struction is:
SOl 23 4 5 6789 -81 00 2 0 0005
Label OPERAND Basi c Autocoder----.-l
215 30 315 40 415 150 1515 601 615
FIGURE 146.
Tape Skip
xxx6 TSK
The specified channel is conditioned so that the tape unit will space forward about four inches before writ-ing in the next write instruction. The tape passed in the write operation is erased. The unit on 'which the spacing takes place is the first unit, on a channel, which is in-structed to write following the skip instruction for any unit on that channel.
This command is used after rewriting a record several times has failed to correct an error detected by the two-gap head, usually due to a defection on the surface of the tape. It is usually followed immediately by a write operation. If-the next instruction for that channel is a read command, no skipping takes place~ and the skip instruction loses its effect on any subsequent write command. Any other type of operation that intervenes before a write command does not affect the function of skip on the write command.
EXAMPLE: To condition a tape unit on channel 3 to space forward about 4 inches prior to writing, on the next write instruction:
SOl 23 4 5 6789
±83 00 y 0 xxx6
Position four can designate any tape unit, on that channel, that is available to the stored pro-gram.
Normally, the unit is the same one designated by the subsequent write instruction; it is the write instruction that spaces the specific tape unit. Sign can be either plus or minus. Positions 6-8 can con-tain any digits.
TIMING: If a tape-write operation has been preceded by a skip instruction, 40 milliseconds are added to write time for Model II units, and 27 are added for Model IV.
AUTOCODER EXAMPLE (Figure 147): The assembled instruction is:
SOl 23 4 5 6789 +82 00 5 0 0006
Tape End of Fife Off
xxx7 TEF
Any time that a tape unit senses a foil strip while writ-ing, or a tape mark while readwrit-ing, the tape indicator light on that unit turns on, and an EOF condition code
results (see section on Automatic Priority Processing).
This instruction turns it off. Any time that the BOF indicator is on, a read or write operation involving that tape unit causes an BOF priority condition (see section on Automatic Priority Processing).
EXAMPLE: To turn off the BOF indicator for tape unit 5 on channell:
SOl 23 4 5 6789
±81 00 5 0 xxx7
Sign can be plus or minus. Positions 6-8 can con-tain any digits.
TIMING: 108 microseconds.
AUTOCODER EXAMPLE (Figure 148): The assembled instruction is:
SOl 23 4 5 6789 +81 00 1 0 0007
Tape Set Lower Density
xxx8 TSLD
The tape unit specified by positions 1 and 4 is set to operate at a density of 200 characters per inch. If the unit is a 729 II, its passing speed will be 15,000 char-acters per second on subsequent read or write opera-tions; if the unit is a 729 IV, its speed will be 22,500 characters per second.
If the tape is to be read, its characters must have the same density. If not, an error (Priority condition code 1) is indicated.
EXAMPLE: To set tape unit 3 on channel 2 to a density of 200 characters per inch:
SOl 23 4 5 6789
±82 00 3 0 xxx8
Sign can be either plus or minus. Positions 6-8 can contain any digits.
TIMING: 108 microseconds.
AUTOCODER EXAMPLE (Figure 149): The assembled instruction is:
SOl 23 4 5 6789 +82 00 5 0 0008
Tape Set High Density
xxx9 TSHD
The tape unit specified by positions 1 and 4 is set to operate at a density of 556 characters per inch. If the unit is a 729 II, its character rate will be 41,667 char-acters per second on subsequent read or write opera-tions; if the unit is a 729 IV, its rate will be 62,500 characters per second.
If the tape is to be read, its characters must have this same density. If not, an error (Priority condition code 1) is indicated.
EXAMPLE: To set tape unit 5 on channel 1 to a density of 556 characters per inch:
SOl
23 4 5 6789±81 00 5 0 xxx9
Sign can be either plus or minus. Positions 6-8 can contain any digits.
TIMING: 108 microseconds.
AUTOCODER EXAMPLE (Figure 150): The assembled instruction is:
SOl
23 4 5 6789 +81 00 2 0 0009Data Flow
Data flow for all tape read and write operations that involve movement of information between tape and core storage is described in the section on Block Transmis-sion.
Included in these operations are:
Tape Read
Tape Read per Record Mark Control Tape Write
(P)TR (P)TRR (P)TW
Tape Write per Record Mark Control (p) TWR
Tape Write with Zero Elimination (P)TWZ
Tape Write per Record Mark Control and
with Zero Elimination (P)TWC
The other tape operations do not involve the flow of data, but are instructions to a specific tape unit or chan~
nel; to backspace, rewind, write a segment mark, etc.
REGISTERS AFFECTED: For the read and write opera-tions (listed above), the record-definition register, transmission registers A and B, the adder, and the RDW address register; for tape-mark write and tape segment-mark write, transmission regis-ters A and B only (none of these regisregis-ters is ad-dressable) .
Label OPERAND Basi c Autocoder---l Autocoder
25 30 35 40 45 50 55 601 65 70
FIGURE 147.
Label
25 30
OPERAND
35 40 45
Basic Autocoder---l
50 55 601
Autocoder
65 70
FIGURE 148.
Label
30
OPERAND
35 40
25 45
Basi c Autocoder---l
50 55 601
Autocoder
65 70
FIGURE 149.
Label
30
OPERAND
35 40
25 45 Basi c Autocoder---l
50 55 601
Autocoder
65 70
FIGURE 150.