PRODUCT DESCRIPTION
SubsystemConfiguration
Dual Drive Support
Two drives may be accessed via a common interface cable, using the same range of I/O addresses. The drives are jumpered as device 0 or 1 (Master/Slave), and are selected by the drive select bit in the Device/Head register of the task file.
All Task File registers are written in parallel to both drives. The interface processor on each drive decides whether a command written to it should be executed; this depends on the type of command and which drive is selected. Only the drive selected executes the command and activates the data bus in response to host I/O reads; the drive not selected remains inactive.
A master/slave relationship exists between the two drives: device 0 is the master and device 1 the slave. When the Master is closed (factory default, figure
Cable Select Option
CSEL (cable select) is an optional feature per ANSI ATA specification. Drives configured in a multiple drive system are identified by CSEL’s value:
–If CSEL is grounded, then the drive address is 0.
–If CSEL is open, then the drive address is 1.
Jumper Location / Configuration
JUMPER CONFIGURATION |
|
|
|
|
Master/Slave |
|
|
|
|
Only drive in single drive sys tem* | C |
|
|
|
Master drive in dual drive system* | C |
|
|
|
Slave drive in dual drive system | O |
|
|
|
Cable Select |
|
|
|
|
Disabled* |
| O |
|
|
E nabled |
| C |
|
|
Cylinder Limitation |
|
|
|
|
Disabled* |
|
| O |
|
E nabled |
|
| C |
|
|
|
|
|
|
Factory Reserved |
|
|
| O |
|
|
|
|
|
Key * = Default C = Closed (jumper installed) O = Open (no jumper) |
Figure
PCBA Jumper Location and Configuration
Cylinder Limitation Jumper Description
On some older BIOS', primarily those that
2 – 5