Service Manuals, User Guides, Schematic Diagrams or docs for : IBM 24xx 2420 A32-0004-0_2420_Model_7_OEM_Oct68
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File No. S360-0S
Form A32-0004-0
Systems Reference Library
IBM 2420 Model 7 Magnetic Tape Unit
Original Equipment Manufacturers' Information
This manual contains detailed electrical, mechanical and cabling
considerations and specifications concerning tape control-tape unit
interface for the IBM 2420 Model 7 Magnetic Tape Unit.
Preface
This manual is for use by designers and engineers when
designing devices which will interface with the IBM 2420
Model 7 Magnetic Tape Unit. It contains all electrical,
mechanical and cabling requirements necessary for Model 7
operation. The reader's detailed knowledge of computer
techniques and terminology is assumed.
First Edition (October, 1968)
Changes axe periodically made to the specifications herein; any changes will
be reported in subsequent revisions or Technical Newsletters.
This manual was prep axed by IBM Systems Development Division, Product
Publications, Depaxtment 265, PO Box 1900, Boulder, Colorado 80302.
A fonn is provided at the back of this publication for reader's comments.
If the fonn has been removed, comments may be sent to the above address.
Requests for copies of IBM publications should be made to your IBM
representative or to your local IBM branch office.
ii
Contents
Introduction . 1 Cables . 8
Operator Panel Lights 2 Connectors 8
Operator Panel Pushbuttons 3 Drivers and Terminators. 8
2420 Interf\lce . 3 Tape Unit Tester 16
Input Signal Lines 3 Tester Switches and Controls 16
Output Signal Lines 6 Tester Signal Hubs 18
Ground and dc Power Lines . 8
I Ilust ratio ns
Figure Title Page Figure Title Page
IBM 2420 Model 7 Magnetic Tape Unit v 9 Tape Unit/Tape Control Signal Cable Connector
1 Functions/Specifications/ and Requirements 1 Pin Assignments 13
2 Interface Lines: Specifications 4 10 Write Bus Terminator 14
3 Tape Unit Select Lines . 5 11 Write Bus Receiver . 14
4 Tape Unit Not Ready Lines 7 12 Control Line Terminator 14
5 Power Cable and Signal Cable Data 9 13 Control Line Driver . 15
6 Power Cable and Signal Cable Connector and 14 Control Line Receiver 15
Contact Data 10 15 Read Bus Driver and Terminator 15
7 AC Power Cables and Connectors: Schematic and 16 Metering-Out Line Terminator 15
Pin Assignments 11 17 Field Tester (Part 5420330) 17
8 Signal Connectors: Schematic and Pin 18 Field Tester Control Settings 18
Assignments 12
ill
Abbreviations
ac alternating current kg kilogram
amp ampere kva kilovolt~p
asm assembly
AWG American wire gage LP load point
BCD binarY coded decimal m meter, minute
bkwd backward rna milliampere
B/M bill of material mm millimeter
BOT beginning of tape ms millisecond
bpi bits per inch
BTU British thermal unit NA not applicable
NFP not fIle protect
C centigrade NR not ready
cfm cubic feet per minute NRZI nonreturn to zero indiscrete
em centimeter NS not specified
dc direct current P parity
PE phase encoded
EOF end of fIle PVC poly-vinyl chloride
EOT end of tape
EPO emergency power off R/W read/write
F fahrenheit sec second
fwd forward sel select
SLT solid logic technology
gnd ground
TC tape connector, tape control
HD heavy duty TI tape indicate
IBG interblock gap UL Underwriters Laboratory
Ind indicator usec microsecond
ips inches per second
v volt
kb thousands of eight-bit bytes vac volts alternating current
kcal kilocalorie vdc volts direct current
iv
IBM 2420 Model 7 Magnetic Tape Unit
v
INTRODUCTION forward or backward direction. (Each block written is
read back by the two-gap read/write head and checked in
The IBM 2420 Model 7 Magnetic Tape Unit reads or the tape control.) Figure 1 summarizes functions, specifI-
writes nine tracks on half-inch (12,7mm) magnetic tape. cations, and requirements of the 2420-7.
Writing is in the forward direction, while reading is in the
Character istic Specification
Recording medium Half-inch (12,7 mm) magnetic tape
Data format Nine-track; eight data bits (0-7) plus parity (P) bit
Recording method and density Phase-encoded (PE) at 1600 bytes per inch (BPI)*
Tape speed Read or write - 200 inches per second (ips) *
High speed rewind - 500 inches per second. *
Time from stopped position Forward - 2.0 ms average (2.2 maximum)
to 90 percent of full (200 ips*) speed Backward - 2.5 ms average (3.5 maximum)
Data rate 320,000 bytes per second or 640,000 hexidecirnal digits per second
Time per byte 3.1 microseconds passing time at 200 inches per second (ips*)
Interblock gap (I BG) length and time O.6-inch (15,2 mm) length, 3 milliseconds passing time at 200 ips*
Rewind and rewind-unload Rewind - 1.0 minute
operation times (2400 ft) Rewind-unload - 1.1 minutes
Rewind and rewind-unload Rewind - 25 microseconds
disconnect times Rewind-unload - 1 millisecond
Forward/backward status 16 milliseconds
change (reversal) time**
Load point (BOT) to first byte Approximately 45 milliseconds (inCluding reversal time)
Tape reels Standard IBM (2400ft.) 10.5-inch or 8.5-inch reel, or mini-reel
(Optional tape cartridge uses only ,standard IBM 10.5-inch reel.*)
Tape capacity 2400 feet max. (10.5-inch reel*)
Tape requ irements Series/500, Dynexcel, IBM Heavy Duty, or equivalent (IBM tape formulations
prior to Heavy Duty or Dynexcel, or similar formulations, cannot be used.)
Time to 'tape drive ready' Time from mounted file reel to 'tape drive ready' is approximately
seven seconds.
Read/write head Construction: two-gap (0.150 inch [0,81 mm] between gaps)
Height/width/depth 67 x 30.5 x 29.5 inches (170 x 78 x 75 cm)
Weight 940 Ibs. (427 kg)
Figure 1. Functions/Specifications/and Requirements (Part 1 of 2)
1
Heat output 7900 BTU/lir (1.991 kcal)
3
Airflow 700 cfm (20m /m)
Power requ irements 2.9 kva
60 cycle/three phase/208 or 230 volts (Domestic)
50 cycle/three phase/ 195,220, 235, 380, or 408 volts (World Trade)
Environmental requirements Operating Nonoperating
Room temperature
Relative humidity 20% - 80% 8%-80%
Maximum wet bult
Service clearances Front and rear: 36 inches (91,4 cm)
Left and right sides: 30 inches (76,2 cm)
Special features None.
* 1600 bpi = 63 bytes/mm ** The tape unit maintains status (forward/backward) of the
200 ips = 500 cm per second operation it has performed. Reversal time must be added for
500 ips = 1300 cm per second every forward following a backward operation, every backward
8.5 inches = 21,6 cm following a forward operation, and for every forward
10.50 inches = 26,7 cm operation initiated at load point.
2400 feet = 742 meters
Figure 1. Functions/Specifications/and Requirements (Part 2 of 2)
OPERATOR PANEL LIGHTS
Operator Panel Lights Condition Indicated When Light Is On
Ready Indicates the tape unit is properly loaded, the start pushbutton pressed, and tape unit can be activated by
the tape controL Turned on by pressing the start pushbutton if:
a. Tape unit is loaded and tape is in columns
b. Reel door is interlocked
c. Tape unit is not searching for load point.
Pressing the start key while tape is in motion, as in a load/rewind operation, does not light the ready light
until load-rewind is complete. The reel door should not be opened while the ready light is on. Manual
control is indicated when light is off if the tape unit is not rewinding or loading and the reel door is
closed.
Select Indicates this tape unit is addressed by the computer. An addressed tape unit must be 'ready' before
receiving program instructions.
File Protect Indicates that a loaded tape unit is fIle-protected (can neither write or erase) because:
a. No me reel is mounted or
b. The fIle reel does not contain a write-enable ring or
c. A load-rewind operation is in progress or
d. An unload operation is in progress.
CB Indicates that a circuit breaker tripped, the gate thermal tripped, or a fuse opened
Tape Indicate Indicates that a light-to-dark transition at the end of the end-of-tape (EOT) marker was sensed during a
forward operation. Indicator is turned off by the light-to-dark transition of the opposite end of the same
marker during a backward operation.
Load Check Indicates a thread failure or a tape leader longer than thirty feet.
2
OPERATOR PANEL PUSH BUTTONS
Operator Panel Pushbuttons Tape Unit Response to Pressed Pushbutton
Load-Rewind Operative when tape unit is not in ready status. Moves tape to load point if the unit is loaded, or threads
tape to load point and loads tape into columns if the unit is unloaded.
Start Puts the tape unit in ready status and under computer control and turns on ready light if:
a. Reel door is closed
b. Tape is in columns
c. Tape unit is not rewinding.
Disables all manual controls except 'reset'.
Rewind-Unload Operative if the tape unit is not in ready status or rewinding and tape is in columns. Rewinds tape to load
point and unloads tape onto the file reel. Closes cartridge (if used). Opens power window at the end of an
unload operation. Opens power window if tape unit is unloaded.
Reset Removes tape unit from ready status and computer control. Performs the following:
a. Stops tape during low-speed rewind or
b. Reduces high-speed rewind to low-speed rewind or
c. Stops tape motion during load or unload operations or
d. Turns off load check light and
e. Raises power window.
2420 INTERFACE Go (TC9)
The 2420 interface consists of 24 input Signal lines, 25 Controls tape motion; it is conditioned after the status
output signal lines, 1 ground line, and 2 dc voltage lines. lines have been set to establish the operation to be
Specifications for 2420 interface lines are given in Figure performed. The go line must be active for all operations
2. that move tape forward or backward, except for rewind
and rewind-unload. Tape motion is controlled internally
Input Signal Lines for these operations.
All input lines are SLT level with a milllmum active
Back ward (TC 11 )
(down) level of +1.2 volts and a minimum inactive (up)
level of +2.5 volts. Puts the tape unit in backward status. If the go line is
active with 'backward status' set, tape moves backward; if
Select (TC77, 79, 86, 88, 97, 99, 106, and 108) backward status is not set, tape moves forward. The tape
Each of these eight input lines selects a particular tape unit remains in backward status unless reset by 'set read
unit (0-7) from the group connected in-line to a common status' or 'set write status.' Since tape can only be written
control unit. An active select line gates the selected tape forward, 'backward' sets 'read status' in the tape unit.
unit, allowing it to receive and transmit all subsequent
Set Read Status (TC25)
signals from and to the control unit. Because the select
signal for any tape urilt is always taken from TC77, select Sets the tape unit in read status and deconditions the
lines are rotated in each TU to TU cable. See Figure 3. write circuits. The tape unit remains in read status until
'set write status' becomes active. 'Set read status' pre-
sumes a forward read, and, therefore, resets 'backward
status.'
3
Input Lines (From Tape Control)
dc Voltage
Rise or Fall Time Pulse Width Level
Line Name (Maximum) (Minimum) UP DOWN
Select 0.25 usec NS* +2.5 +1.0
Backward 0.25 usec 9.5 usec +2.5 +1.0
Go 0.25 usec NS +2.5 +1.0
Set Read Status 0.25 usec 10.5 usec -#2.5 +1.0
Set Write Status 0.25 usec 7.9 usec +2.5 +1.0
Rewind NS* NS* +2.5 +1.0
Rewind-Unload NS* NS* +2.5 +1.0
Metering Out NS* NS* +2.5 +1.0
Write Bus NS* NS* +0.6 +0.3
Command Response
Rewind Not Ready or Select & at LP
Rewind-Unload Not Ready
Backward Backward Status
Set Read Status Select and Read Status
Set Write Status (Not) Select and Read Status
*NS-not specified
Output Lines (To Tape Control)
Maximum dc Voltage
Rise or Fall Time Response Time Level
Line Name (Maximum) (from Select) UP DOWN
Model 1, 2, 3 1 usec 2.0 usec +2.5 +1.5
Select & T I Off 1 usec 6.8 usec +2.5 +1.5
Select & at LP 1 usec 6.2 usec +2.5 +1.5
Select & Read Status 1 usec 6.2 usec +2.5 +1.5
Select & NS* 6.2 usec +2.5 +1.5
Not File Protect
Backward NS* 6.2 usec +2.5 +1.5
Write Inhibit See Note See Note +2.5 +1.5
Not Ready NS* NS* +1.9 +1.0
Read Bus NS* NS* 0.1 vp/p@
180KC
Note: Determined by interblock gap (IBG) length
and the time necessary to reach full tape speed.
*NS- not specified
Figure 2. Interface Lines: Specifications
4
I T'P'~~I
Tape Control 1 I -.l
I I I
I I I
I
I I I
I I I
I
I I
I
I I I
I I
I I
I I I
Connector Connector Connector I
I/O
1'\ Connector A \ Receptacle I Receptaclel ' \
\
Receptacle
Connector
I Receptacle \
Connector
\ R~~ePtacle I
~';l 'Its A
~
A 'B A tl A I
603
Read Select "0"
Read Select" 1"
--"" ..J 77 1_ ~ 77~>-
~::;: 77>+- ~- ~ 77:>-1-
~ . ~~g~::~: 77>- r-L-
Address Lines { B05 1 79>- - - - ~ 79!>- 79>1- - - ~ 79:>--1- Tape Units RDS "1' 79>- - - - "A"
~
Read Select "2" I DS "3"
(Read Select B08 ~ 86>-1- - - ~ 86!>- --- 86>1- - - --~ 86 1>- I- ~I2_throu gh 6 RDS "2' 86>- - - - Terminator
4,5,6, Read Select "3" I I
88> - - -~
RDS "7"
~
~
810 106>1- - - 1061>-1- 106>- - - -
Not Shown) Read Select "7" 1
88!>-
DS';Q- ~ Signal H-1'RDS "3' :' Block
D09,
( Data and Command
-.l
-, 108> - - --~ 10a!>- 1--- 108> - - ~ 1081>-1- I-- J Connectors I 108>- - - -
~ ~,
I Lines (Common)
'-'
Tape Ctrl
I
>----- > : '-./
Intercon-
I'.
>-1- - -
I '---
Interconnecting
'- /
Interconnecting
~
>-t - - - - -
Signal I necting Cable or Jumper Cable or Jumper
Cable Cable or
Jumper
Note:
All address lines terminated by terminator block at final drive
Broken lines indicate tape unit internal wiring.
Figure 3. Tape Unit Select Lines
Set Write Status (TC13) Select and Not File-Protected (TC192)
This input line puts the tape unit in write status and Indicates that a selected and ready tape unit can perform
conditions tape unit write circuits. The tape unit remains a write operation because it is not file-protected. A tape
in write status until 'set read status' or 'backward' unit is file-protected (writing or erasing of tape is
becomes active. 'Set write status' also resets 'backward prevented) when the file reel does not contain a write-
status.' enable ring.
Note: Because write checking is accomplished by reading, Select and TI Off (TC196)
read circuits are conditioned during both read and write Active when the tape indicator of the selected tape unit is
operations. off; this indicates the selected tape unit has not reached
the useful end of tape. TI is set by sensing the light-
Write Bus (TC1, 3, q,
17, 19,21,31,33, and 35) to-dark transition at the end of the EOT marker during a
These nine input signal lines (0-7 and P) gate data from forward operation; it is reset by sensing the light-to-dark
the tape control directly to the write head drivers. Data transition of the opposite end of the same marker during
sent by the tape control determines time and duration of a backward operation.
write head flux reversals.
Select and Read Status (TC162)
Rewind (TC39) This output line indicates read status when active, and
This input line causes the tape unit to perform a rewind write status when inactive; it is effective only while model
operation (tape is rewound to the load point). Rewind is 1, 2, and 3 lines are active.
at high speed if there is more than approximately 60 feet
of tape on the take-up reel; otherwise, it is a low speed Not Ready (TC142, 144, 156, 158, 172, 174, 186, and
rewind. 188)
This output line indicates the addressed tape unit (0-7) is
Rewind-Unload (TC41) connected but not ready. A tape unit is not ready if it is
Like rewind, this input line causes tape to rewind to load unloaded, in reset status, or performing a rewind opera-
point. In addition, tape unloads, and the power window tion.
opens, preparatory to changing reels. In a tape unit configuration that utilizes a 2816
Switching Unit, the active state of 'not ready' may also
Metering Out (TC23) indicate the tape unit is switched; that is, the tape unit is
This input line is active when the system's conditions are operating with another control unit. Because a selected
met for running usage meters and the control unit is not tape unit sends its own 'not ready' signal out on TC142,
off-line. The tape unit meter stops only if the metering- not ready lines are rotated in TV to TV cables. so the
tape unit next to the control unit has the 'not ready (n)'
out line becomes inactive, if the tape unit is unloaded and
line at the proper TC pin. See Figure 4.
not rewinding, or if the tape unit is at load point.
On a rewind-unload command, the tape unit drops the
Metering out is terminated in each individual tape unit.
model lines (TCI80, 182, and 184) before activating the
not ready line.
Output Signal Lines
All output lines are SLT level with a minimum active
Read Bus (TC82, 84, 93, 95, 102, 104, 113, 115, and 122)
(down) level of +0.3 volt and a minimum inactive (up)
level of +2.5 volts.
These nine output lines (0-7 and P) carry the data read
from tape to the tape control for a read operation and
Models 1, 2, 3 (TC180, 182, and 184)
for checking a write operation.
These output lines identify the tape unit model and
indicate the tape unit is selected and ready. All three lines Backward Status (TC164)
(1, 2, and 3) active at the same time identify a model 7
tape unit. This output line is active when the tape unit is in
backward status. Conditioning the go line causes back-
Select and at Load Point (TC198)
ward motion of tape-for example, in backspacing.
Indicates the tape on the selected tape unit is pOSitioned
at load point. This line is reset if the tape is unloaded and
not rewinding or if tape is moved forward.
6
Tape Control Tape Unit "0" Tape Unit "1" Tape Unit "7"
Not Ready Not Ready Not Ready
(TU 0) (TU 1) (TU 7)
~
\. Connector A
G08
Not Ready "0" ~ "'\
144 ~ -
I
--f-< I NR 0 '-"
142 ... -1;.._-'-,(
~R 1 ~I
r-
l-r-f-< - - - - --(- -
142
J~
,
142 <- - -~r~ ~~'N}~.J.-r-,....k--14-2-~-, _L.--------.
Not Ready {
Lines (Not
Gl0 Not Ready "1'.'
G12<--~:~:::~::;~ I \
I .,. 144
156
-(- ___ -f-<
~r--- f-< 156
144
~~~
r-f-< 144 <: __ _
f-f-< 156 <----
f-<
f-<
144...
156
_NR~~I_'
NR 3
NR 7
j Tope Units
2.throu g h 6
.
NRO
NR 1
..J:1"-'N:-7:R 2 -+-+<
::-::-
-= _-
.,. 144 ~ ~
156 ~
Terminator
Ready 4, 5,
J04 -(-- Not ReadY-;7;;---r--1---l-- -f-< 158 ~ - - f-< 158 -< . f-f-< 186 ~ - - - f-< 186 NR 0 S'gnal \:.-'N":':R':"'='3-+-+< 157 -(- - - - Block
6 Not Shown)
J13"'1- -
~ Data and Command
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