Figure 4.6.3 Unit Selection - Fujitsu M2361A Customer Engineering Manual

(2) Selection
Unit selection must be performed before instructions such as Seek and
Read/Write can be sent from the controller.
When a drive receives Unit Select Tag (USLTG) and Unit Select 1, 2, 4
(USLCTl, USLCT2, and USLCT4), the drive compares it with its own address.
The dr i ve address is set by DIP swi tches on the display panel. I f the address
sent from the controller matches the address of the drive when the Open
Cable Detector (OCDTR) and Power Ready (PWRDY) signals are high, Select
Latch (SLCTL) is set, Enable signal (ENABL) is generated, Unit Selected
(SLCTD) is sent to the B-cable, and, at the same time, the
driver/receivers for the A-cable are enabled for transmission.
While the drive is selected, instructions (Seek, RTZ, Read/Write, and
others) may be received. The drive is released when one of USLTG, OCDTR,
PWRDY goes low.
Figure 4.6.3 shows the unit selection sequence timing diagram.
Unit Selcl.:t Tag
--------~--------
Unit Select 1. 2,4
Power Ready
===============*================~~============~=========*========
Open
Cable Detedor
Select latch
Unit Selected
Figure 4.6.3 Unit selection
(3) Outline of access control
4 - 54
The access control circuit has five latches for controlling access
operation.
The operation modes and the outputs of the latches are as follows:
1. Sequence RTZ
2. System RTZ
3. Manual RTZ
4. Direct seek
5. Fine control
The following access mode la tches (Tabl e 4.6.
I)
can be moni tored on the 7
segment display on the display panel PCB.
B03P-4825-0002A ... OIA