Write Data Circuit Block Diagram - Tandon TM-100-1 Operating And Service Manual

SIDE
SELECT
D
BUFFER
N WRITE DATA
C
NWRITE GATE
N WRITE PROTECT
UNIT SELECT
WRITE
GATE
WRI T E
DATA
TRIGGER
WRITE
CURRENT
SOURCE
ERASE
DELAY
LOGIC
0
0
WRITE
SELECT
LOGIC
IN WRITE )
SIDE
SELECT
LOGIC
WRITE
DRIVER 1
WRITE
DRIVER 2
ERASE
CURRENT
SOURCE
-
•
'i'
READ/
WRITE
COILS
IN INTERNAL- READ DISABLE
~ - - - - - - - W R I T E BUSY)
Figure 3-6
Write Data Circuit Block Diagram
Circuit Description
Data comes in on Pin 22 of the interface connector in pulse form. Subsequently it is buffered by IC 2E, then fed to
a flip flop , IC SC. THe two outputs of the flip flop , through drive IC 2B, alternately turn on 01 and 02, which alter-
nates the write current to the selected head. R31 controls the amount of write current. (See Figure 3-7.)
03 is activated by the write gate through IC 2B, IC 3B, and IC 3D (see Section 3.3.1.5).
04 is designed to allow write current to flow only after the five-volt line is high enough to forward-bias CR14, CR
15, and CR 16, which protects the disk from extraneous data being written when power is initially applied to the
disk drive.
3.3.1.6 Side Select (N SIDE SELECT)
Functional Description
When the Side Select signal is true (low), Side 1 of the disk drive is selected for read /write operations . When this
signal is false (high) , Side O of the disk drive is selected (see Figure 3-10). The Side Select signal must be stable
3-10