Control Data 1700 User manual

CONTROL DATA
CORPORATION
CONTROL DATA®
1700 COMPUTER SYSTEM
1732-A/B MAGNETIC TAPE CONTROLLER
REFERENCE MANUAL

REVISION
A
(9-15-70)
Publication No.
60330800
© 1970
REVISION RECORD
DESCRIPTION
Manual released; this manual supersedes the 1732- A /B Magnetic Ta~e Controller section of the
obsolete CONTROL DATA® 1700 COMPUTER SYSTEM STANDARD PERIPHERAL REFERENCE
MANUAL, Pub. No. 60182700.
Rev. T of the obsolete manual.
The information contained herein is the same as that found in
Address comments concerning this
manual to:
by Control Data Corporation
Control Data Corporation
Technical Publications Department
4201 North Lexington Avenue
Arden Hills, Minnesota 55112
or use Comment Sheet in the back of
this manual.
Printed in the United States of America

PREFACE
This manual gives reference information for the CONTROL DATA® 1732-A/B Magnetic Tape
Controller which may be used in conjunction with the 1705 Interrupt Data Channel of the 1700
Computer. For reference information on 1700 Basic Peripheral Equipments (which attach
directly to the 1704 Basic Computer ) see the 1700 Computer System Reference Manual,
Pub. No. 60153100.
60330800 A
iii

Introduction
Functional Description
1
2
3
4
1
2
3
4
System Relationship
Magnetic Tape
Tape Format
Parity
Cyclic Redundancy Check (CRC)
Master Clear
Reply / Rej ect
File Protection
Program Protection
Typical Configurations
Tape Format
Physical Layout of Tape
File Protection Ring
Tape Format
1732 Operations
Motion Control
Director Status 1 Response Bits
60330800 A
CONTENTS
1
Programming
1
Summary of Programming
1
Information
3
Addresses
3
Operations
6
Status Response
6
Interrupts
6
Programming Example
6
Manual Operation
7
7
FIGURES
2
4
5
7
5
6
7
TABLES
4 5
8 6
9 7
10
Switches and Indicators
Operating Procedures
Format of Q Register
(A) for Control Function
(A) for Unit Select
Director Status 2 Response Bits
Controller Select Codes
Tape Unit Select Codes
8
8
10
11
16
18
18
21
21
24
8
9
9
10
11
14
v

INTRODUCTION
FUNCTIONAL
DESCRIPTION
System Relationship
60330800
1732-A/B MAGNETIC TAPE CONTROLLER
The CONTROL DATA ® 1732 Magnetic Tape Controller synchronizes data
transfer between a 1700 Computer System and up to eight 608 or 609 Tape
Transports. This section describes the physical system, the programming
information, and the operating procedures for the 1732 and 608/609.
As Figure 1 illustrates, the 1732 may be attached directly to the AQ Channel
or it may be attached to a 1706 or 1716 converter. The tape transports with
which the 1732 is associated are the 7-track 608 and 9-track 609. These
may be intermixed on the system as the user desires.
The equipment number switch, located on the controller, designates the con-
troller address (0 through F hexadecimal). Anyone of the eight tape trans-
ports attached to the controller may be selected.
Character-Assembly/Disassembly Operating Modes
The 1732 operates in either Character mode or Assembly/Disassembly
mode. In Character mode the 1732 sends data bits 0- 5 or 0-7 to the tape
transport (depending upon whether the tape unit is 7 or 9 track). The upper
8 or 10 bits are ignored by the controller. Likewise, when the computer
reads data from the tape via the 1732 in Character mode, each tape word is
sent to the computer in bit positions 0-5 (or 0-7); the remaining bits are
ignored by the computer.
However, in AID mode each computer word sent to the tape via the 1732 is
disassembled into two sections before being sent to the tape unit. If the
computer is sending data to a 7-track 608 tape unit, data bits 8-13 comprise
the first tape word and data bits 0-5 comprise the alternate tape word. Bits
6, 7,14 and 15 are ignored.
1

If the computer is sending data to a 9-track 609 tape unit, data bits 8-15
comprise the first tape word and data bits 0-7 comprise the alternate tape
word.
If the controller, operating in AID mode, reads an odd number of tape words,
the lower bits of the last assembled word will be filled with zeroes. The
FILL status bit will s~t to indicate that this portion of the assembled word is
not a tape word.
1705
OIR
STO
ACC
BUS
I
N
T
E
1704
R
1732
R
u
p
T
5
AO
CH
1705
OIR
STO
ACC
BUS
1706/
1716
I
N
T
E
1704
R
1732
R
u
P
T
5
AO
CH
Figure 1. Typical Configurations
2 60330800 A

Magnetic Tape
Tape Format
60330800 A
Magnetic tape provides a high-speed, nonvolatile storage medium. The tape
has a plastic base and is coated on one side with a magnetic oxide. Informa-
tion is recorded on this coating. Extreme care is taken to prevent error-
causing imperfections.
Information is read (detected) or written (stored) by passing the oxide side
of the tape over read/write heads. Information may be written on any or all
of the tape tracks. During a Read or Write operation, the tape pasces over
seven or nine evenly aligned heads; therefore, all bits of the tape word may
be simultaneously recorded, one bit on each track.
A non-return-to-zero (change-on-ones) recording scheme is used. In this
system, magnetic particles on the tape are aligned in either the positive or
negative direction. A binary "1" is recorded by reversing the alignment
(polarity); no polarity reversal indicates a "0". Thus, each track of the tape
is fully magnetized and the polarity is reversed as each" 1" bit is recorded.
Table 1 and Figure 2 describe the data format of magnetic tape. A line or
frame of tape data consists of a 6- bit or 8- bit tape word and a parity bit.
In a 608, tracks 0 through 5 contain the data bits and track 6 holds the parity
bit. In a 609, tracks 0 through 7 contain the data bits, and track 8 holds the
parity bit.
Density
The controller, when connected to the 608 tape transport, may be selected to
synchronize data at a rate of 200, 556 or 800 bits per inch. When the con-
troller is connected to a 609 tape, 800 bpi is the only possible density selec-
tion. The tape speed in both tape handlers is 37-1/2 inches per second.
Mode
The 608 tape transport records data in either of two modes: Binary mode,
which uses odd parity; or BCD mode. which uses even parity. Since there is
no BCD conversion in the 1732, the BCD "zero" character is illegal and
should not be used.
BCD can not be used with the 609 tape transport.
3

Tracks
Tape Speed
Density (bpi)
Parity
TABLE 1. TAPE FORMAT
seven
37 1/2 ips
200
556
800
608
Vertical Binary-odd
BCD-even
placed in seventh track
Longitudinal even parity check character
spaced 4 frames from last
data character.
Cyclic Redundancy none
Code Word
File Mark A BCD 178 six inches from
last record. The file mark is
followed by a longitudinal check
character of BCD 17
8,
Tape Mark none
Initial Gap 3.0 inches minimum for write
0.5 inches for read
Record Gap
BOO BPI -0.00125
556 BPI -O.OOIB
1 ,200 BPI -0.005
0.687 inches minimum
0.960 inches maximum
0.750 inches nominal
609
nine
same
800
odd - placed
in ninth track
even parity check
character spaced 4
frames from the CRC
code word.
spaced 4 frames from
last data character
none
A 238 6 inches from
the last record. It is
followed by an ident-
ical check character.
same
0.50
0.75
0.60
inches minimum
"
"
maximum
nominal
BCD BIT 608 BINARY
rPOSITION
(BIT P('SITION
,
1:::: ::: !
0.032 .l..lliD]1 I I II -L 0 04B
(READ) I (WR'TE)
,- t
TRACK
DETAIL
111111111111 4
111111111111 5
111111111111 •
111111111111 7
.,
p .,
5 :I
.,
7 ,
111111 11111 ~ ·1111 III 8
11111111 III ; jill "" A
11111111 III \ t"llill 8
11111111111 I "-.';.;.".;.;".;.;,,_<'-- ____ -'
NOTES:
~R~c:r.;;-f~~~:,: l ~ -1- - ~E:O~D~- - - - - - -
j kONGITUDINAL
CHECK C!-tAR GAP
200 BPI - 0.02
556 BPI - 0.0074
BOOBPI- 0.005
I. OXIDE SIDE UP ON DIAGRAM, RECORDING HEAD ON SAME SIDE AS OXIDE.
2. WRITE FREQUENCY 7.5 KC ::!: ,0/
0•
20.8'5 KC tl%. OR 30"'C :tlo/a.
3. AvERAGE STEADY STATE TAPE SPEED 37.5 ips.
Figure 2. Tape Format
4 60330800 A

Records and Files
Data recorded on the tape is arranged in groups called records and files.
A record consists of consecutive frames of information. A minimum of one
frame of information constitutes a record. Adjacent records are separated
by a 0.6 inch (609) or 3/4 inch (608) unrecorded area called a record gap.
In a 609 tape transport a cyclic code word and a longitudinal parity check
character are recorded at the end of each record. In a 608 tape transport
the cyclic code word is not present. A file consists of a group of records.
Adjacent files :are separated by recording an end-of-file marker six inches
from the last record in the file. In the 608 the end-of-file marker is called
File Mark; in the 609 the end-of-file marker is called Tape Mark.
Load Point
The load point is a reflective marker indicating the beginning of the usable
portion of the tape. It is located at least 10 feet from the beginning of the
tape.
End-of-Tape Marker
The end-of-tape marker is a reflective marker placed not less than 18 feet
from the end of the tape. This provides approximately 10 feet of tape trailer
and enough tape to hold a record of 96,000 characters after the end-of-tape
marker is sensed. See Figure 3.
END OF TAPE
REFLECTIVE
SPOT
0
1"
I -2
LOAD POINT
REFLECTIVE
SPOT
\
'ORWARO.OIRECTION /
PORTION
DIA. REEL
\
18' MINIMUM 10' MIMINUM
PHYSICAL
BEGINNING
OF TAPE
Figure 3. Physical Layout of Tape
60330800 A 5

Parity
Cyclic Redundancy
Check (CRC)
Master Clear
Reply/Reject
6
The controller may be selected to operate with even (BCD) vertical parity or
with odd (binary) vertical parity. The controller generates an even longitu-
dinal parity check character for each physical record.
During a Write, the read heads of the tape transport transfer the newly
written character to the controller. The controller performs a parity check
and sets the Parity Error status bit if an error has occurred. If the Alarm
interrupt has been selected, an interrupt occurs.
During a Read, the parity bit recorded on the tape is checked against the
character. The Parity Error status bit sets if an error occurs. If the
Alarm interrupt has been selected, an interrupt occurs.
The Cyclic Redundancy feature is an additional check of the accuracy of data
transmission and reception between the controller and the tape unit. The
CRC, used by the 1732 only in conjunction with the 609, is accomplished by
writing a cyclic code word at the end of each record. When the record is
read by the controller, the code word should toggle the CRC register to an
all clear condition if the data is correct. If the CRC determines that the
data is incorrect, a parity error is indicated via the Parity Error light and
via a parity error status response. Note that if the number of data char-
acters in arecord is even, the parity bit of the Cyclic code word will be odd;
if the number of data characters is odd, the parity bit of the code word will
be even.
Pressing the 1704 Computer CLEAR switch clears all interrupt selections
and error conditions of a connected 1732. It clears a BCD selection and AID
mode selection, but does not clear a connection.
The Reply signal indicates an operation requested is possible. It is re-
turned to the computer or converter within 4 IJ,sec and at least 0.2 IJ,sec
after the request is initiated. A Reject signal indicates the operation re-
quested cannot or should not be performed at that time. If neither a Reply
nor a Reject is received for 4.0 IJ,sec, the computer generates an Internal
Reject.
60330800 A

File Protection
Program Protection
The back of a tape reel has a slot near the hub for a plastic file protection
ring (Figure 4). Writing on a tape is possible only when the reel contains a
file protection ring. Reading from the tape is possible with or without the
ring. Removal of the file protection ring after writing avoids loss of valu-
able records due to accidental rewriting.
Figure 4. File Protection Ring
The 1700 I/O system has a program protect feature which reserves pro-
tected equipment for use by protected programs. A 608 or 609 Tape Trans-
port is protected by setting the PROGRAM PROTECT switch on the 1732
controller chassis which corresponds to the setting of its Unit Select switch.
When its PROGRAM PROTECT switch is set, all instructions for that tape
transport (except the two status requests) are rejected if their Program
Protect bit is not set or the 1704 protect system is not enabled. To explain
in more detail:
1) A protected program may select any unit that is physically in the
system, loaded, under external control, and Not Busy.
2) An unprotected program cannot select a tape unit whose switch is
in the protected position.
60330800 A 7

PROGRAMMING
Summary of
Programming
Information
8
After an attempt by an unprotected program to select a protected transport.
the status is:
1) Not Ready. Protected -No tape transport is selected and the re-
quested transport is protected. Any previously selected transport
is unprotected and is now deselected.
2) Ready, Protected - The previously selected tape transport is still
selected. Once selected, a protected transport can be deselected
only by using an Output from A instruction whose Program Protect
bit is set to initiate either a Deselect Tape Unit function or a new
Select Tape Unit function.
Tables 2 through 5 and Figures 5. 6. and 7 provide the experienced pro-
grammer with the information necessary to program the 1732. The following
paragraphs further define this information.
15
W
D
00
01
10
II 10
7 6 2 I 0
I E
W: CONVERTER CODE
E: EQUIPMENT NUMBER
D: 01 RECTOR
Figure 5. Format of Q Register
TABLE 2. 1732 OPERATIONS
COMPUTER INSTRUCTION
Output from A Input to A
Write Read
Control Function
Director Status 1
Unit Select
Director Status 2
60330800 A

Figure 6. (A) for Control Function
TABLE 3. MOTION CONTROL
BITS 10-7
OFA
MOTION FUNCTION
0001 Write Motion
0010
Read Motion
0011 Backspace
0101 Write File Mark/Tape Mark
0110
Search File Mark/ Tape Mark
Forward
0111
Search File Mark/ Tape Mark
Backward
1000
Rewind Load
1100 Rewind Unload
Figure 7. (A) for Unit Select
60330800 A 9

Addresses
10
TABLE 4. DIRECTOR STATUS 1 RESPONSE BITS
BIT SET IN
A REGISTER MEANING
0
Ready
1
Busy
2 Interrupt
3
Data
4 End of Operation
5 Alarm
6
Lost Data
7
Protected
8 Parity Error
9
End of Tape
10
Load Point
11
File Mark
12
Controller Active
13
Fill
14 -15
(Not Used)
TABLE 5. DIRECTOR STATUS 2 RESPONSE BITS
BIT SET IN
A REGISTER MEANING
0
556 bpi
1
800 bpi
2
(Not Used)
3 Seven Track
4 Write Enable
5-15
(Not Used)
The W = 0 signal plus bits 10-7 of the Q register are used to select the de-
sired 1732. If the 1732 is connected via the A/Q Channel, the W field of Q
is always loaded with zeros. If the 1732 is connected to a converter, the
converter code is placed in the W field, but the converter supplies the W = 0
signal to the controller. Bits 0-1 of Q are used to specify an operation.
Figure 5 illustrates the format of the Q Register. Table 6 lists the values of
E required to select a controller with a given equipment number setting.
60330800 .A

Operations
TABLE 6. CONTROLLER SELECT CODES
E
EQUIPMENT
E
EQUIPMENT
(BITS 10-7 OF Q)
NUMBER
(BITS 10-7 OF Q) NUMBER
0000 0 1000
8
0001 1 1001 9
0010
2
1010
A
0011 3 1011 B
0100
4
1100
C
0101 5 1101 D
0110
6 1110
E
0111 7 1111 F
Bits 10- '( of the A register are used along with the contents of Q and Output
from A to select a tape transport. (See Unit Select. )
The D field of Q is combined with a 1704 Input from A or Output from A in-
struction to specify an operation (see Table 2). The operations initiated by
an Output from A may be further modified by the contents of the A register.
See Table 3. Figure 6. and Figure 7. The following paragraphs define
these operations.
Operations Defined by Q and Output from A
Write: A Write transfers data from the computer to the controller which
generates a parity bit and writes the data plus parity bit on the tape. To
perform a Write. load Q with W = 00*, E = equipment number setting of de-
sired 1732 controller and D = 00. An Output from A instruction initiates the
transfer of the computer word to the tape. ** Any number of consecutive
characters sent to the tape are written (along with a parity bit) on the tape as
a single record. Whenever the computer breaks the continuity of the com-
puter word outputs. the controller initiates an End of Record sequence. The
End of Record sequence leaves three blank character spaces, writes the
cyclic code word. leaves three more spaces. writes the longitudinal parity
check character. and leaves a record gap.
*W is written as two digits; the left. binary; the right. hexadecimal. If the
1732 is connected to the computer via a converter. W equals the appropriate
converter code. See the reference material for that converter.
**If the Output is a buffered output via the converter. the Output from A in-
struction supplies address information to the converter. The converter
controls the buffer,ed operation.
60330800 A 11

Jf no new Control Function is received from the computer, tape motion stops.
A Write is rejected if Not Ready or Write Motion has not been initiated.
Control Function: The Control Function operation specifies operating con-
ditions for the selected controller and transport and initiates tape motion.
To perform a Control Function, load Q with W = 00, E = equipment number,
and D = 01. Load A ac<;!ording to Figure 6 and Table 3. Execute an Output
from A.
The controller rejects control functions if it is Not Ready, the End of Opera-
tion status condition is not present, an illegal code exists in bits 7-10 of A,or
if the tape transport is Busy and Rewind or Rewind Unload function is selected.
Table 3 lists the legal motion control codes. One motion control plus any or
all clears and interrupt selections may be selected simultaneously or in-
dividually. The requests are honored in this order: clears, interrupt selec-
tions, motion control. The following describes these codes:
1) Clear Controller (AO = 1) - directs the clearing of all interrupts,
interrupt selections, errors, and File Mark/Tape Mark status. All
other select codes coded with it will also be honored. For example,
A =0011 would clear the controller and the select interrupt on end of
operation.
2) Clear Interrupt (AI = 1) - clears all interrupts and interrupt re-
quests. If an interrupt request is coded along with a Clear Interrupt,
that selection is honored, but any previous selections are cleared.
3) Data Interrupt Request (A2 = 1) - causes an interrupt to be gener-
ated when an information transfer may occur. The interrupt re-
sponse is cleared by the Reply to the data transfer. The request
and response are cleared by a Clear Controller or a Clear Interrupt
code.
4) End of Operation Interrupt Request (A3 = 1) - causes an interrupt to
be generated at the end of an operation. The request and response'
are cleared by a Clear Controller or a Clear Interrupt code.
5) Alarm Interrupt Request (A4 = 1) - causes an interrupt to be gener-
ated upon a condition which warrants program or operator attention.
The Alarm interrupt is generated by any of the following conditions:
a) End of tape
b) Parity error
c) Lost data
12 60330800 A

60330S00 A
d)
File mark/tape mark, or
e) The transport goes to Not Ready during an operation.
6) Write Motion (A10 -7 = 0001) - initiates write motion. A direct or
buffered output must follow for data transfer to occur. If the tape is
at load point, the first word is written 3 inches after load point. All
data requests are rejected while the unit is Busy and before End of
Operation status. For a non-stop Write, initiates a Write Motion or
Write File Mark function within 5 ms after End of Operation status/
interrupt.
If Write Motion is selected and no data transfer follows, the con-
troller locks out and terminates the Write Motion function when it is
time to write the first character on tape. Forward drops to the
selected transport and the transport goes Not Busy after 4 ms but no
End of Operation is generated. To recover from this error condition,
a Unit Select or Clear Controller function can be issued to accept
another motion function. An External Master Clear from the 1700
console will also reset End of Operation.
7) Read Motion (A10-7 = 0010) - initiates read motion. A direct or
buffered input must follow for data transfer to occur. If the tape
is at load point, data can be read within 0.5 inch. CDC tape does
not have information this close to the load point, but other formats
do. All data requests are rejected while the unit is Busy and before
End of Operation status. Read motion terminates by absence of data
from the data handler for three frames. If the computer (or con-
ver~er) stops requesting characters, data transfer stops, but the
tape continues to move to the end of the record. For a non -stop
Read, initiate a Read Motion within 4 ms after End of Operation
status/interrupt. If a data transfer request is not received by the
controller in time to complete the transfer properly, a lockout pre-
vents further transfers from the block and all subsequent data trans-
fer requests are rejected. When data is read but not accepted by the
computer, the Lost Data status bit is set if Data Request is late
and data overlaps in 0 register.
S) Backspace (A10-7 = 0011) - moves tape backward one record. Back-
space from load point and non-stop backspace and possible.
9) Write File Mark/Tape Mark (A10-7 = 0101) - moves tape forward
approximately 6 inches and writes a 1-character word of 17S (File
Mark) in a 60S or a 23S (Tape Mark) in a 609. The normal End of
Operation sequence follows the Tape Mark/File Mark, writing the
longitudinal check character. When the transport is operating in
binary mode, the File Mark registers a parity error.
10) Search File Mark/Tape Mark Forward (0110) - moves tape forward
until a File Mark or Tape Mark is detected; an end of operation is
generated and tape motion stops.
13

11) Search File Mark/Tape Mark Backward (0111) - moves tape back-
ward until a File Mark or Tape Mark is detected. When it has been
detected, an end of operation is generated, and tape motion stops.
If no file mark or tape mark is detected, an end of operation will be
generated and motion will stop at load point.
12) Rewind Load (A10-7 = 1000) - rewinds tape at high speed to load
point. The controller remains Busy until tape is positioned at load
point and End of Operation status/interrupt occurs.
13) Rewind Unload (A10-7 = 1100) - rewinds tape to load point. The
tape transport becomes Not Ready upon acceptance of the command.
Manual intervention is required to reload the tape and place the
transport in a Ready condition.
Unit Select: A Unit Select selects a tape transport and its operating condi-
tions or deselects a transport. To perform a Unit Select, load Q with W =
DO, E = equipment number, D = 10. Load A according to Figure 7 and
Table 7, and do an Output from A. Tape unit, density, and mode (BCD or
binary) can be selected simultaneously or individually. Unit Select is re-
jected if Controller Active or a program protect fault occurs or if an illegal
code is selected (for example, two densities chosen).
TABLE 7. TAPE UNIT SELECT CODES
BITS 9-7 UNIT SELECT SWITCH
OFA
SETTING
000
0
001 1
010 2
011 3
100 4
101 5
110 6
111
7
1) Character Mode (AD = 1) - In this mode the computer word con-
sists of the lower 6 or 8 bits only.
2) BCD (AI = 1) - Data is read or written in even parity (608).
3) Binary (A2 = 1) - Data is read or written in odd parity.
14 60330800 A