Phase-Encoded 1600 BPI Magnetic Tape DLP

The PE Mag Tape DLP supports the 5E magnetic tape drives. It is also used to interface to the CP3680 data communications front-end processor.

A typical configuration consists of one or more B9499-11 MEC (PE/NRZ Tape Unit Controllers) and a string of up to 16 B9495 Tape Drives.

Style Speed
B9495-82 75IPS
B9495-83 150IPS
B9495-88 200IPS

I/O Descriptors

Operation MLI OP SYS OP S L1 L2 L3 Addresses
ECHO 1 48
Echo * 0 0 0
TEST 2 44
Rewind * 1 U 0
Wait for Not Ready * 2 U 0
Wait for Ready * 3 U 0
Cancel * 4 U 0
Space/Forward 54 * 8 U 0 C Address Required
Space/Backward 54 * 9 U 0 C Address Required
Rewind/Unload 44 * B U 0
ID * C 0 0
Test Unit * F U 0
WRITE 4 42
Erase * 4 U M A and B
Write * 6 U M Addresses
Write Tape Marks * C U 0 Required
READ 8 40
Forward * 2 U 0 A and B
Backward 41 * 3 U 0 Addresses
Required

U designates unit number. (U=0 is unit 16).

C Address designates space count. If space count is decimal, 2 MSD = from 1-100 records. If space count is binary, 2 MSD = from 1 - 256 records.

M designates mask bits as follows:

  • 8-bit: Used by Space Forward/Backward. Indicates space count variant digits contain a decimal (8-bit = 1) or a binary (8-bit = 0) value.
  • 4-bit: Used by Read Forward/Backward and ECHO to inhibit the Record Longer than Host Buffer exception condition.
  • 2-bit: Used by Read Forward/Backward, WRITE, ERASE and ECHO to inhibit the Record Shorter than Host Buffer exception condition.
  • 1-bit: Used by Space Forward/Backward to modify the space operation. The MEC is requested to space one record at a time (1-bit = 0) or to space continuously (1-bit = 1).

Test/Wait Ready - Test/Wait Not Ready

The Test/Wait operators are not used on tape devices, even though they are functional. The design of the V Series I/O subsystem will mark a channel as busy one a Test/Wait operator is issued to some drive on the channel. The channel will remain busy until the Test/Wait operation completes. While the channel is busy no operations can be issued to other tape drives connected to the channel. To allow operations to be issued to all drives on the channel, periodic Test Unit operations are issued to idle tape drives to detect a status change, rather than issuing Test/Wait operators.

PE Magnetic Tape DLP Result Descriptor Word 1

A B C D
8 MEC
NOT READY
UPW ERROR
DLP
TO
MEC
BOT RECORD
LONGER
THAN HOST
BUFFER
4 DESCRIPTOR
ERROR
UPW ERROR
MEC
TO
DLP
EOT RECORD
SHORTER
THAN HOST
BUFFER
2 VERTICAL
PARITY ERROR
(MLI)
TAPE
PARITY
ERROR
TAPE MARK TAPE UNIT
BUSY
1 LONGITUDINAL
PARITY
ERROR
(MLI)
TAPE UNIT
NOT READY
WRITE
LOCKOUT
REWINDING

PE Magnetic Tape DLP Result Descriptor Word 2

A B C D
8 HOST
ACCESS
ERROR
ERASE/
REWIND
NOT
INITIATED
SPACE
COUNT
MSD
SPACE
COUNT
LSD
4 TIMEOUT CANCEL
COMPLETED
SPACE
COUNT
MSD
SPACE
COUNT
LSD
2 DATA
TRANS-
FERRED
ZERO SPACE
COUNT
MSD
SPACE
COUNT
LSD
1 ILLEGAL
REWIND
INITIATED
ZER SPACE
COUNT
MSD
SPACE
COUNT
LSD

The C and D digits contain the two digit remaining space count. If the 8-bit of the M variant is true, the space count is decimal, otherwise it is binary.

PE Magnetic Tape DLP TEST/ID Result Descriptor Word 2

A B C D
8 0 0 X X
4 0 1 X X
2 0 0 X X
1 0 0 X X

X Represents field-installed jumpers.

Each Tape DLP can be jumpered with a specific code. This code is not used by the V Series MCP and is typically left unjumpered, returning a value of 00. (This feature was implemeted for the Large Systems MCP.)

dlps/pe_magnetic_tape.txt · Last modified: 2012/02/04 15:07 by scott
 
Except where otherwise noted, content on this wiki is licensed under the following license: CC Attribution-Noncommercial-Share Alike 3.0 Unported
Recent changes RSS feed Donate Powered by PHP Valid XHTML 1.0 Valid CSS Driven by DokuWiki