IBM 5114 Maintenance Information Manual page 106

Cylinder I n - - O u t
Location
o
1 2 3 4 5 -- 40 -- 74 75 76
Access 0 100 1 1 0 1 0 1 1
Access 1
110011 1 0 0 1
Access 2
o
1 1 0 0 1
0 1 0 0
Access 3 001 100 0 1 1 0
The four access pulses are sequenced to move the heads
in (toward the drive hub) or out (away from the drive
hub).
Status Register
This block provides sense information to the system. It
senses the condition of the latches and several lines in
the adapter. This block turns on associated bits in the
diskette sense and the access sense bytes of the 'bus
in' line.
Latch
Write Mode
Read Mode
Diag 1 or 2
Index
Erase Gate
Diskette 1 or
Diskette 2
eRC Error
Read /Writen
Overrun
New Media
MFM
Inner Track Select
(filter control)
Inner Tracks
Head Engage
Head Selected
Access Lines
3-28
Bit
Diskette Sense Bit 0
Diskette Sense Bit 1
Diskette Sense Bit 2
Diskette Sense Bit 3
Diskette Sense Bit 4
Diskette Sense Bit 5
Diskette Sense Bit 6
Diskette Sense Bit 7
Access Sense Bit 0
Access Sense Bit 1
Access Sense Bit 2
Access Sense Bit 3
Access Sense Bit 4
Access Sense Bit 5
Access Sense Bits 6 and 7
Read and Write Data Buffers
These buffers provide a temporary storage for data as it
travels to and from the adapter.
Access Control (Register)
This register takes the output of the access control byte,
bits 6 and 7, to activate two of the four access lines.
The access lines cause the stepper motor to rotate
moving the read/write heads across the recording
surface of the diskette. (See Stepper Motor in this
section.)
R/W
&
Head
This register controls the condition of the write gate.
When the 'write gate' line is active, the read circuitry is
degated. When the 'write gate' line is inactive, the read
circuitry is active.
Serdes and Control
This block is made up of the write serializer, the read
deserializer, and the controls necessary to count the
bits.
On a write operation, this block receives bytes of data
and sends them to the write circuitry serially bit by bit.
On a read opertaion, this block receives data from the
diskette serially bit by bit, builds bytes of data, and
sends the data to the system byte by byte.
Oscillator
The oscillator is only used in a write operation. It is
used to insert clock bits in the write data at the correct
times. These clock bits are used on a read operation for
sychronization in the VFO circuitry. The VFO circuitry
deletes the clock bits from the data before sending the
data to the Serdes register.
VFO
This block is physically a part of the VFO circuitry. It is
only used in a read operation. This block provides
clocking for the raw data and subdevice selection.
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