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G A 3 2 0 0 2 20
tBM 341013411
Systems Magnetic
TapeSubsystems
ComponentDescription
IBnfi
First Edition (December 1972)
The information in this book is subject to significant change. Any such changes will be
published in ncw editions or technical newsletters.
Requestsfor copies of IBM publications should be marJc to your IBM representative or to the
IBM branch office serving your locality.
A form for reader's comments is at the back of the book. Address any additional comments to
Half-lnch Tape Writing, Dept. 26T, Bldg. 023, IBM Br:rulder. If the form has been removed,
c o m m e n t s m a y b e s e n t t o t h e a b < i v ea d d r e s s .
o Copyright Intcrnational Business Machines, 1973
Preface
'fhis
manual describesthe IBM 3410/3411 Magnetic Tape Subsystem,Models 1,
2, and 3. In most instances, operational descriptions are limited to the channel
and Qommand level. Operations common to all I/O devices are described in
IBM System/360 Principles of Operation, Form GA22-6821, and IBM
System/370 Principles of Operation, Form GAZZ-7OOO.
Subjects covered include keys and lights, tape handling procedures, status and
sense information, and error recovery procedures.
Audience
Systems programmers who are writing programs for magnetic tape.
Systems engineers who are planning installations using magnetic tape.
Salespersonnel.
Preface 3
Contents
Introduction to Magnetic Tape Subsystems 7
Magnetic Tape Subsystem Specifications 13
Operating Procedures l5
Tape Handling and Storage. l5
Operator's Panel l6
Power On/Oft Procedures l8
Status Information and Sense Data l8
Error RecovervProcedures 32
Figures
Figure l. IBM 3410/3411Fearure Summary 8
Figure 2. CommandByte Coding (Part I of 2) 9
Figure 2. CommandByte Coding (Part 2 of 2) . n
Figure3. IBM 3410/3411Magnetic Tape Subsystem Specificarions t3
Figure4. Operator'sPanel t6
Figure 5. Unit Statusand Sense Byte Summary l9
Figure 6. Statusand Sense Indicator (Bits) CheckingSequence 33
Contents 5
I B M 3 4 1 0 / 3 4 1 IM a g n e t i T a p eS u b s y s t e m
c
3 4 1 0/ 3 4 1 l C o m p o n e n t D e s c r i p t i o n
Introduction to Magnetic Tape Subsystems
Magnetic tape is widely used as an input,/output medium becauseit rapidly stores
large amounts of information in compact, easily handled form. Tape can be used
for storing intermediateresults and for permanent storageof large files of data.
Although the recording is permanent, any previous record is erasedduring the
write operation. This means that tape can be used again and again witln
significant savingsin recording costs.
A magnetic tape subsystemconsistsof a tape control and one or more tape units.
A tape unit is an electromechanical device that transports magnetic tape past a
read,/write head, and either records (writes) data on the tape or senses(reads)
data previously recorded on the tape. A tape control is an electronic drsvice that
controls the operation of severaltape units. 'I'he tape control selectsa specific
tape unit, establishes
the necessary conditions for an operation, provides timing
signalsand delays, and controls the transfer of data between the tape r.rnitand
host system. Status and senseinformation, which monitor the progressof an
operation, are accumulatedby the subsystemand sent to the host system upon
request.
To write on tape, the tape control sends tape-motion control commands,write
control commands,and data to the tape unit. The tape unit then moves the tape
past the read/write head and writes the data on tape. To read from tape, the
tape control sendstape-motion control commands and read control commands to
the tape unit. The tape unit then moves the tape past the read,/write head, reads
the data from the tape, and sends the data to the tape control. The tapreunit
also rewinds, spacestape, and unloads tape upon command from the tape
control.
T h e I B M 3 4 1 0 / 3 4 1 1 M a g n e t i cT a p e S u b s y s t e m o n s i s t s f o n e 3 4 1 1 M a g n e t i c
c o
T a p e U n i t a n d C o n t r o l a n d u p t o f i v e 3 4 1 0 M a g n e t i cT a p e U n i t s . T h e 3 4 l l
contains the tape control and power suppliesfor the subsystem.The 34ll
c o m p l e t e l yc o n t r o l s t h e 3 4 1 0 s . T h e t a p e u n i t p o r t i o n o f a 3 4 l 1 i s i d e n t i c a lt o
that in the 3410.
There are three models of the IBld 34lO/3411 subsystem.
The Model 1 subsystemmoves tape at 12.5 inches per second (ips) resulting in a
maximum data rate of 20,000 bytes per second. A maximum of three !t4l0s can
be included in this subsystemfor a total of four tape units.
The Model 2 subsystemmoves tape at 25 ips resulting in a maximum data rate
of 40,000 bytes per second. A maximum of five 3410s can be includeclin this
subsystemfor a total of six tape units.
The Model 3 subsystemmoves tape at 50 ips resulting in a maximum data rate
of 80,000 bytes per second. A maximum of five 3410s can be includedL this
in
subsystemfor a total of six tape units.
N o t e : I n t e r c o n n e c t e d 4 1 0 s a n d 3 4 l l s m u s t b e t h e s a m em o d e l . M o d e l s c a n n o t
3
be intermixed.
Tape units attach to the tape control via individual interface cables. This is called
a "radial attachment," and it allows a tape unit to be disconnectedfrom the tape
control without affecting other tape units of the subsystem. Each tape unit signal
connector in the tape control is associated with a unique tape unit address. When
the tape control communicateswith a tape unit, the interface signalsarr: routed
only to the selectedtape unit.
lntroduction to Magnetic Tape Subsystems
T h e 3 4 l O / 3 4 l l t a p e s u b s y s t e m a n o p e r a t ei n t h r e e d e n s i t y m o d e s ; 1 6 0 0 b p i
c
( e e ) s i n g l ed e n s i t y ,8 0 0 / 1 6 0 0 b p i d u a l d e n s i t y ( n i n e - t r a c k ) ,o r 2 O O / 5 5 6 / 8 0 0 b p i
seven-track. On the 341 I tape control single density is standard. Dual density
and seven-trackare specifiedfeatures. On the 3410 tape unit, including the tape
unit portion of the 3411, all density modes are special features. One special
feature must be ordered for each 3410; single density, dual density, or
seven-track. The features are mutually exclusive;only one can be installed on a
tape unit. Figure I summarizesthe features availableon the 3410/3411.
Subsystem Feature IBM 341 Magnetic
1 I B M 3 4 1 0M a g n e t i c
Function T a p eU n i t & C o n t r o l T a p eU n i t { l n c l u d e s
t a p eu n i t i n 3 4 1 1 )
1 6 0 0B P I Single Standard F e a t u rN o .3 2 1 1
e
9-Track only Density
1600/800 BPI Dual Feature FeatureNo.
NRZI 9-Track Density No. 9150 321rl or 3221
1600 BPI PE,/ Seven Feature Feature No.
2 0 0 / 5 5 6 , / 8 0 0B P I Track No.9160 3211 or 6550
NRZI 7-Track
Figure l. IBM 3410/3411 Feature Summary
The Single Density feature allows nine-track tape units to read or write 1600 bpi
PE. No mode set command is required for the read or write operations.
The Dual Density feature allows nine-track subsystems operate in PE mode at
to
1600 bpi or in nine-track Nnzl mode at 800 bpi . Before initiating a write
operation, the channel must first issue a Mode Set 2 command to establishthe
operating mode in the tape control. A Mode Set 2 command is not necessary for
nine-track read operations.
The Seven-Trackfeature allows subsystems with a mixture of seven- and
nine-track tape units to read and write in either seven-trackNRZI mode or
nine-track PE mode. In seven-trackNRzt mode, reading and writing are done at
200,556, or 800 bpi . Before initiating a seven-trackread or write operation, the
channel must first issue a Mode Set 1 command to establishthe operating mode
in the tape control. Tape controls with the seven-trackfeature also have the
translator and data converter installed.
When on, the translator causeseight-bit EBCDIC (Extended Binary Coded
Decimal InterchangeCode) bytes from the system to be written on tape as
six-bit BCD (Binary Coded Decimal) charactersand six-bit BCD charactersto
be read from tape and translatedto their eight-bit EBCDIC equivalent. Data
rates are not changed when using the translator, nor is there any change in tape
unit operation.
When on, the data converter causes4 six-bit characters(24 bits) to be written
on tape for every 3 eight-bit bytes received from the system. Reading
seven-tracktape with the data converter on reversesthe processby converting
the 4 six-bit tape charactersto 3 eight-bit bytes. When on, the data converter
reducesthe data transfer rate to 75oh of the operating rate with the data
converter off. Data conversioncan only be used when moving tape forward, that
is, writing or reading forward.
Note: Both the translator and data converter are turned on or off by the Mode
Set 1 command.
The subsystemis under the control of the host system which can be System/360
M o d e l s2 2 , 2 5 , 3 0 , 4 0 , a n d 5 0 o r S y s t e m / 3 7 O o d e l s 1 2 5 , 1 3 5 , 1 4 5 , 1 5 5 , a n d
M
158. The host system instructs the 3410/341 I subsystemto perform specific
tasks. The tape control receives,decodes,and executesthe instructions. To
execute a command, the tape control instructs the selectedtape unit to perform
t h c d e s i r e do o e r a t i o n .
I 3 4 1 0 / 3 4 1 1 C o m p o n e n tD e s c r i p t i o n
A Start I/O instruction from the host system initiates a tape operation. The
system also sendsone of the following commands (Figure 2.ltart 1 of 2) to
designatethe clpera{.ion subsystemis to execute:
the
Write
This command records data on tape. The parity of each byte is checked when it
is received from the channel and again after it is written (readback check). The
write command also generatesan interblock gap at the end of each data block.
In pE mode, a write command issuedwhen tape is positioned at the
beginning-of-tape(aOr), generatesa pF.identification burst and a 3-inch (76
mm) gap before data is recorded on tape.
l n N n z t m o d e , a w r i t e c o m m a n d i s s u e dw h e n t a p e i s a t B O T ,g e n e r a t e s 5 - i n c h
a
( 1 2 7 m m ) g a p b e f o r e d a t a i s r e c o r d e do n t a p e .
Commands Command Byte Hex
0 1 2 3 4 5 6 7
Write 0 0 0 0 0 0 0 1 01
Read Forward 0 0 0 0 0 0 1 0 o2
Read Backward 0 0 0 0 1 1 0 0 0c
Sense 0 0 0 0 0 1 0 0 o4
Rewind 0 0 0 0 0 1 ' r 1 ol
Rewind Unload 0 0 0 0 1 1 1 ' r OF
Erase ap
G 0 0 0 1 0 1 1 1 17
Write Tape Mark 0 0 0 1 1 1 1 1 Its
B a c k s p a c eB l o c k 0 0 1 0 0 1 1 1 27
B a c k s p a c eF i l e 0 0 1 0 1 1 1 1 2F
Forward Space Block 0 0 1 1 0 1 1 1
Forward Space File 0 0 1 1 1 1 1 1 3F
Data Security Erase r 0 0 1 0 1 1 1 9l
R e q u e s tT r a c k - l n - E r r o r 0 0 0 1 1 0 ' r 1 1B
Mode Set 1 See Part 2 of this figure.
Mode Set 2 See Part 2 of this figure
Figure 2. Command Byte Coding (Part 1 of 2)
Read Forward
This command reads data from tape as tape is moving forward. The tape unit
reads data until an interblock gap is detected. The tape control checks the parity
of each byte before it is sent to channel. When reading in PE mode, single-track
errors are corrected before the data is sent to channel.
For dual density subsystems, the mode in which the read command operatesis
determined when tape is at BOT. If the PE identification burst is detected,the
tape control and tape unit are set to read tape in 1600 bpi pr, mode. If the PE
identification burst is not detected,the tape control and tape unit are set to read
tape in 800 bpi NRzl mode. The tape unit retains the mode setting until the tape
is again at BOT.
For seven-tracksubsystemsread density is determined by a Mode Set I
command.
Introduction to Magnetic Tape Subsystems
Read Backward
This command is similar to a read forward command except that tape moves
backward.
Sense
This command transfers sense data from the subsystem to the host system. The
sensebytes are stored in the tape control and tape unit. SenseBytes 0, 1, and 2,
and bits 0 to 6 of SenseByte 3 are identical to the IBM 2400-seriesand
3420/3803 subsystems.The 34lO/34 1l subsystemusesnine sensebytes. See
"Status Information and SenseData" for further description of the status and
sensebytes.
Request Track-in-Error
This command returns the track-in-error information (SenseByte 2) from the
host system to the subsystem. The tape control uses the data to correct the next
data block read. This command is effective only when correcting single-track
read errors during nine-track NRZI operations. It is executed but not effective
during PE and seven-trackoperations.
Write Tape Mark
This command writes a special block on tape that is used to separate the files on
tape. This special block is generatedby the subsystem;no data is transferred
from channel. A readback check is performed on the tape mark. If an error is
detected,tape is repositionedand the tape mark is rewritten.
In PE mode with tape at BOT, a pE identification burst is written and a 3-inch
(76 mm) gap is generatedbefore the tape mark is written.
In NRZI mode with tape at BoT, only the S-inch (127 mm) gap precedesthe tape
mark.
Erase Gap
This command erasestape for a predetermineddistance. If tape is not at BOT,
the distance erasedis 3.6 inches (91 mm).
In PE mode with tape at BOT, the PE identification burst is written, then a 3-inch
(76 mm) gap is erased.
In NRZI mode with tape at BoT, a 5-inch (127 mm) gap is erased.
Successiveerase gap commands can be issued to generate longer gaps.
Data Security Erase
This command erases tape from the point at which it was initiated to the
end-of-tape (Eor) marker. Data Security Erase is acceptedby the subsystem
only when chained to an Erase Gap command. To erase tape beyond the EoT
marker, successiveErase Gap commands must be issued.
Rewind
This command rewinds tape to BOT. If tape is at BOT when the command is
issued,the operation is terminated immediately without error.
Rewind Unload
This command rewinds tape to BoT and then unloads tape. If tape is already at
BOT, tape is unloaded to complete the operation.
Forward Space Block
This command moves tape forward to the next interblock gap.
l0 3410/3411Component
Description
Forward Space File
This command moves tape forward to the interblock gap beyond the first tape
mark encountered.
BackspaceBlock
This command moves tape backward to the next interblock gap or to BOT,
whichever occurs first.
Backspace File
This command moves tape backward to the interblock gap beyond the first tape
mark encountered or to BOT, whichever occurs first.
Mode Set I (Seven-Track Feature)
This command establishes operating conditions in the tape control for subsequent
seven-track read or write operations. The Mode Set I command determines the
density, turns the data converter and translator on or off, and sets subsystem
operations to odd or even parity. The subsystem retains its mode setting until
reset or until it receivesanother mode set command. See Fisure 2. Part 2 of 2.
200 556 800 1600 o d d Even DC oc Translate Translate Command Byte Hex
Parity Parity On off On off 0 1 2 3 4 5 6 7
Mode Set 1 (Seven-Track)
x x x X 0 0 0 1 0 0 I 1?
X X x X 0 0 1 0 0 0 I aa
X x X X 0 0 1 0 1 0 1 1 L6
X X x X 0 0 1 1 0 0 1 1 33
X X x X 0 0 1 1 1 0 1 1 3B
x X X X 0 0 1 0 0 1 53
X x X X 0 1 0 0 0 1
x ,l
X X x 0 0 1 0 1 6B
X x X X 0 1 1 1 0 0 1 73
X X X X 0 1 1 1 I 0 1
7B
X X x X I
0 0 1 0 0 1
X x x X 1 0 0 0 0 1 A3
X X X X 1 0 0 1 0 1 AB
X X x X I
0 r 0 0 1 1
X X x x 1
0 I 1 0 1 1 utJ
Mode Set 2 (Nine-Track)
x 1 0 0 0 0 I 1 a?
x 1 0 0 1 0 I I CB
Note l: Seven-trackMode Set 1 commandsare treated as NOP-reset sensebytes when issuedto a tape controt
without the seven-trackNRzt feature.
Note 2: Nine-track Mode Set 2 commands are treated as NOP-reset sensebytes when issuedto a tape control
without the nine-track NRzl feature.
Figure 2. Command Byte Coding (Part 2 of 2)
Introduction to Magnetic Tape Subsystems 11
Mode Set 2 (Dual Density)
This commandestablishes operatingconditions(1600 bpi or 800 bpi) in the
the
tape control and tape unit for subsequent
nine-trackwrite operations.
The
commandis accepted the tape unit only when the tape unit is at BOTon a
by
write-typecommand.During read operations, mode is automatically when
the set
tape is at BoT. (See"Read Forward.")
1.2 34lO/3411 ComponentDescription
Magnetic Tape Subsystern Specifications
Characteristics Model 1 Model 2 Model 3
Tape Speed (ips) 12.5 25 S0
Write Access Time* 15 ms 12 ms 6 ms
R e a dA c c e s sT i m e * 15 ms 12 ms 6 ms
Data Rate:
1600 bpi 20 kb/sec 40 kb/sec 80 kb/sec
800 bpi 10 kb/sec 20 kb/sec 40 kb/sec
556 bpi 6.95kb/sec 13.9kb/sec 27.8kb/sec
200 bpi 2.5 kb,/sec 5.0 kb/sec t0.0 kb/sec
Time Per Byte:
1600 bpi 50 usec 2b usec 12.b usec
800 bpi 100 usec 50 usec 25 usec
556 bpi 144 usec 72 usec 36 usec
200 bpi 400 usec 200 r.rsec 100 usec
Interblock ap (lBG):
G
Length/Time
Nrne-Track 0.6 inl48 ms 0.6 inl24 ms 0.6 inl12 ms
Seven-Track 0.75 in,/60 ms 0.75 in,/30 ms 0.75 in,/15 ms
R e w i n dT i m e ( t 1 0 % ) 3 minutes 3 minutes 2 minutes
(2400 feet)
T a p eT h r e a d i n g Manual Manual Manual
R e e ls i z e s( i n c h ) 1 0 . 5 ,9 . 5 , 7 , o r 6 ( f o r a l l m o d e l s )
Tape Requirements
The following half-inchtapes can be used: IBM Series/500,IBM Heavy Duty, IBM Dynexcel@,
or competitive formulations which meet the tape and reel criteria in Tape Specifications,
Form
GA32-0006.
Note: IBM tapes other than those named above do not provideadequatereliability
and should
not be used.
* Read Access Time is the intervalfrom issuanceof a Read Forwardcommand given to the
tape control when tape is not at load point, until the first data byte is read when tape is
brought up to speed from stopped status.
* Write Access Time is the intervalfrom the issuanceof a move command to the tape unit
when tape is not at load point, until the first data byte is written on tape when tape is
brought up to speed from stopped status.
Machine Environment
RelativeHumiditv: 20 to 8O%6
Temoeratures:
O p e r a t i n g : 0 t o 9 0 " F ( 1 5 . 6t o 3 2 . 2 ' C )
6
N o n - O p e r a t i n g5 0 t o 1 1 0 " F ( 1 0 t o 4 3 . 3 ' C )
:
M a x i m u mW e t B u l b : 7 8 ' F ( 2 5 . 6 ' C )
Metric equivalents:
1600bpi : 6 3 b y t e sp e r m m 0.6 inches : 15,2mm
800 bpi = 3 1 , 5 b y t e sp e r m m 0.75 inches : 19 mm
556 bpi : 2 1 , 9 b y t e sp e r m m 6 inches = 1 5 2 , 4m m
200 bpi : 7 , 9 b y t e sp e r m m 7 inches : 1 7 7 , 8m m
50 ips : 1 2 7 0m m p e r s e c o n d 8.5 inches : 216 mm
25 ips : 635 mm per second 10.5 inches = 266,7 mm
12.5 ips : 317,5 mm per second 24OOfeet : 732 meters
Figure 3. IBM 3410/3411 Magnetic Tape Subsystem Specifications
Magnetic Tape SubsystemSpecifications 13
Operating Procedureg
This section contains procedures for handling and storing tape, turning power on
and off, and recovering from errors. Also included are descriptions of the
Operator's Panel and of the status and sense bytes. Refer to the IBM
3410/3411 Operator's Guide, Form G232-0004, for additional operating
procedures.
Tape Handling and Storage
Tape Handling
A tape reel that is not in use on a tape unit should always be stored in its
container. Establish procedures to protect magnetic tape from contamination
which causes degraded tape unit performance. Some common rules are:
1. Never leave tape reels or containers exposed. Tape may be damaged, or dust
accumulating on the tape or in the container can contaminate the tape.
2. Erasing a tape reel identification label is a cause of contamination. Use new
labels when changing reel identification. Select a label with an adhesive
backing that does not leave a residue and that can be applied and removed
easily.
3. Never allow a loose end of tape to trail on the floor; dirt picked up in this
manner can reach the tape transport and be passed on to other sections of the
tape.
4. Do not allow smoking in areas where tape is in use. Ashes contaminate tape.
Live ashes can permanently damage the tape surface.
5. Don't touch the tape edges through the reel openings or press on the reel
flanges. Such pressure will compress the tape and damage its edges.
6. Be very careful when removing the write-enable ring. Always unload tape
before removing the write-enable ring; never remove the ring while tape is
loaded on the tape unit.
Tape Storage
To prevent tape contamination and damage during storage, follow these
procedures:
1. Before a tape is stored, securethe loose end of tape with a tape end retainer
to prevent the tape from unwinding in the container.
2. Always store tape in an upright position. Never store tapes flat or in stacks;
accidental damage or reel warpage may result.
3. Store tapes in a cabinet or shelf elevated from the floor and away from
sources of paper and dust. Dust can be transferred from the outside of the
container to the reel during load and unload operations.
Operating Procedures l5
Operator's Panel
trtrtrtr
trtrEtr
Figure 4. Operator's Panel
SELECT
This lamp is turned on when the tape unit is being operated by the tape control.
The tape unit must be ready before it can execute commands from the tape
control.
READY
This lamp indicatesthat the tape unit is capable of executing commands from the
tape control.
To turn on the READY lamp, the tape unit must be loaded, the cover closed, the
STARTkey must be pressed,and tape must not be in motion (as in a load or
rewind operation for example). Pressingthe STARTkey while tape is loading or
rewinding, causesthe READY lamp to turn on after the operation is complete and
tape motion stops.
FILE PROTECT
This lamp indicatesthat the tape unit is not capable of executing a write or erase
command.
T h e F t L E P R O T E C T ' l a m ip t u r n e d o n w h e n t h e t a p e u n i t i s n o t r e a d y ,o r w h e n a
s
file-protected tape reel is mounted. A file-protected reel is one from which the
write-enable ring has been removed. The write-enable ring should be removed
from the back of the tape reel to protect information on the tape from accidental
erasureor rewrite.
TAPE INDICATE
This lamp is turned on when the end-of-tape (eclr') reflective marker is sensed
with tape moving in a forward direction. SensingEot' in write status sets unit
exception. The lamp is turned off when the EOl marker is sensedwith tape
moving in a backward direction.
RESET
Pressingthis pushbutton removes the tape unit from ready status, turns off the
READY lamp, stops tape motion, and prevents the tape unit from respondingt
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