Select Lines Schematic Diagram - Tandon TM-100-1 Operating And Service Manual

TABLE 3-3
POWER CONNECTOR PIN ASSIGNMENTS
Pin Supply Voltage
1 +12VDC
2
Return ( + 12 VDC)
3 Return ( + 5 VDC)
4 +5VDC
3.3.1.1 Select Lines (NDS0-NDS3)
Functional Description
The select lines (see Figure 3-3) provide a means of selecting and deselecting a disk drive. These four (4) lines
(NDS0-NDS3 standard) select one (1) of the four (4) disk drives attached to the controller. When the signal logic
level is true (low), the disk drive electronics are activated and the disk drive is conditioned to respond to Step or
Read/Write commands. When the logic level is false (high), the input control lines and output status lines are
disabled.
SHUNT
1 E
Jt
SELECT O IO t - - - - ~ H
SELECT 1
12
t - - - - ~ H
SELECT
2 14-
1 - - - - - - - ' - H
SELECT
3 6
1 - - - - - = l - - l
+SV
+sv
x:r
8 " - - - ~
our
07
04
Figure 3-3
Select Lines Schematic Diagram
ACTIVITY
LED
A select line must remain stable in the true (low) state until the execution of a Step or Read/Write command is
completed.
The disk drive address is determined by a Select Shunt on the PCBA. Select lines 0-3 provide a means of daisy
chaining a maximum of four (4) disk drives to a controller. Only one line can be true (low) at a time. An undefined
operation might result if two or more units are assigned the same address or if two or more select lines are in the
true (low) state simultaneously .
3-5