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Contents
33FD/53FD/72MD DISKETTE DRIVE I/O Sense Command-I/O Control
AND ATTACHMENT (LEVEL 2) . . 14-1 Sense Command . . . . . . . . 14-32
INTRODUCTION . . . . . . . 14-1 Jump on I/O Condition Command. 14-34
33FD Diskette Drive . . . . . . 14-2 Sense Interrupt Level Status Byte
33FD Diskette Drive Assembly 14-2 Command . . . . . 14-36
33FD Operating Sequence . . 14-3 FUNCTIONAL UNITS 14-37
53FD Diskette Drive . . . . . . 14-4 Data Separator 14-37
53FD Diskette Drive Assembly 14-4 Index Counter . . . . 14-37
53FD Operating Sequence . 14-5 Ready Counter 14-38
72M D Diskette Magazine Drive 14-6 Control Storage Initial Program Load
Autoloader Units . . . . . 14-6 Track Counter . . . . . . 14-38
Diskette Drive Components 14-7 CSIPL Autoloader Sequence 14-38
Logic Cards . . . . . . . 14-7 Read/Write Clock . . . 14-39
Stepper Motors . . . . . . 14-8 Write Trigger . . . . . 14-40
72M 0 Operating Sequences 14-10 Address Mark Detection 14-42
Frequency Modulation Read and Write Circuits 14-12 Bit Ring . . . . . . . 14-42
Modified Frequency Modulation Read and Cyclic Redundancy Character Shift Register . 14-43
Write Circuits . . 14-13 ID Buffer . . . . . . . 14-44
Diskette 1 Format. 14-14 Data Buffer . . . . . . 14-45
Diskette 20 Format 14-15 Sector Sequence Control 14-45
DATA FLOW . . . . 14-16 Track Sequence Control 14-45
OPERATIONS . . . . 14-17 Byte Counter . . . . . 14-46
Diskette Drive Operations . 14-17 Cycle Steal Control 14-46
Seek Operation . 14-17 Interrupt Level 4 Request. 14-47
Read Operation . . . 14-19 DBI Assembler 14-47
Write Operation . . . 14-21 CBI Assembler 14.-47
Write Verify Operation 14-22 Op Decode . . 14-47
Find Sector Identification Operation 14-23 Autoloader Control . 14-47
Write Sector Identification Operation 14-24 Seek Control . . . 14-47
CSIPL Read Operation 14-26 500- Ki lohertz Osci Ilator 14-47
Autoloader Operations 14-27 Error Conditions . . 14-48
Select Slot 14-27 Diskette Drive Errors . . 14-49
Orient 14-27 Autoloader Errors . . . 14-54
Eject . . . 14-27 INPUT/OUTPUT LINES 14-56
Abort . . 14-27
COMMANDS 14-28
I/O Load Command-I/O Control
Load Command 14-28
Autoloader Mode Commands . 14-30
Select Diskette 14-31
Orient . . . 14-31
Eject . . . . . 14-31
Load Heads 14-31
Unload Heads 14-31
Reset Sense . 14-31
Abort . . . . 14-31
Sense 0 through Sense 5 14-31




Contents for 33FD/53FD/72MD Diskette Drive and Attachment (Level 2)
33FD/53FD/72MD Diskette Drive and Attachment (Level 2)
INTRODUCTION The System/34 uses two types of diskettes: Autoloader mode permits the selection of a
Diskette 1 and Diskette 2D. One side of diskette, the loading of this diskette into the
Diskette 1 (33FD, 53FD, or 72MD) and both drive, plus the unloading of that diskette and
The diskette drive and diskette drive attachment sides of Diskette 2D (53FD or 72MD) are used returning it to its correct slot. The autoloader
are located inside the 5340 System Unit. for recording. The two types of diskettes are includes a carriage bed and a picker
System!34 uses a 33FD diskette drive, a 53FD identified by the physical location of the index mechanism; both are driven by stepper motors.
diskette drive, or a 72MD diskette magazine hole e. When a Diskette 1 is inserted in a The carriage bed contains two magazines (each
drive. The diskette drive attachment card and 53FD or 72MD diskette drive, the circuits that magazine can contain 10 diskettes) and three
the data separator card are located on the sense the index hole prevent the use of the I/O slots for insertion and removal of single
A-A2 board. Each diskette drive also contains second side. A Diskette 2D cannot be used in a diskettes by the operator. The carriage bed is
a file control card. The control storage program 33FD diskette drive. There is 1 label cylinder, moved at right angles to the diskette drive by
and the diskette drive attachment with the file 74 primary data cylinders, and 2 alternative the carriage bed stepper motor until the
control card control the diskette drive. The cylinders per diskette. Commands from the selected diskette is aligned with the picker
diskette drive can read a data track, write on a control storage program start the diskette mechanism. The selected diskette is moved
data track, or seek to a data track of a diskette. selection and the read, write, and seek from the carriage bed to the drive and returned
The data separator separates serialized data operations in addition to performing various to the carriage bed by means of the picker and
pulses from clock pulses as they are read from control functions. An index hole in the diskette the picker stepper motor.




DD
the diskette. The data is moved between the references the start of the first sector on the
attachment and main or control storage in cylinder that the data head is on. Diskette drive mode allows the seek, read, and
2-byte bursts by cycle steal. write functions, which are similar to functions
The 72MD is a 53FD type diskette drive with of other diskette drives. The 72MD diskette




~D
The 33FD and 53FD diskette drives have a the diskette turning at double speed. The drive can read and write both one-sided and
continuously turning shaft that turns the 72M D also has a diskette autoloader. The two-sided diskettes.
diskette. A solenoid-loaded data head diskettes can be contained in either of two
(33FD/53FD) or cam-loaded data heads 10-pack magazines or in three manual insertion
(72MD) are moved to the correct data track by slots. All diskettes used for a specific operation




>~D
a stepper motor. A data head can then read or must be the same type and have the same
write the data track. format and may be placed in either magazines
or I/O slots, but not both. The 72M D operates
The 33FD diskette drive records data using in two distinct modes: autoloader. mode and
frequency modulation. The 53FD and 72MD Card Side diskette drive mode.
diskette drives record data using either
frequency modulation or modified frequency
modulation.


Diskette Drive Attachment Diskette Drive
Diskette
I
I
I
I
Index Hole for
Diskette 1
ID I
~ Index Hole for
I Diskette 2D
I
I (one-sided diskette) _ 0 (two-sided diskette)



. Channel
I
I
t ...
I

I
--.. Autoloader
Control
~.'.
....-...
.. I
"'"
I
I
Attachment
Controls

... ....
I
I
r--------~------~~-- ..~~ ~~
...
Drive Station
~~ ~, ... ~
Data Separator
...
I I Control

I
I
I
I
I
I
I
I
I
Diskette Drive and Attachment (Level 2) 14-1



II
14-2



33FD Diskette Drive When the cover is closed, the continuous light" The stepper motor wheel. is on the end of
from the light-emitting diode G) points toward the stepper motor shaft. The stepper motor CD
the phototransistor. Every time the diskette turns in steps of 90 degrees in either direction
33FD Diskette Drive Assembly turns, the index hole in the diskette lets the under the control of access pulses. The stepper
light from the light-emitting diode reach the motor wheel engages the leadscrew wheel