Subsystem Configuration, Cylinder Limitation

PRODUCT DESCRIPTION

Subsystem Configuration

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 J50 is closed (factory default, figure 2-1), the drive assumes the role of master; when open, the drive acts as a slave. In single drive configurations, J50 must be closed.

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

Darkened jumper pins indicate factory-installed (default) shunts.

JUMPER CONFIGURATION	J50	J48	J46	J44	J42
Master/Slave
Only drive in single drive system*	C
Master drive in dual drive system*	C
Slave drive in dual drive system	O
Cable Select
Disabled*		O
Enabled		C
4092 Cylinder Limitation
Disabled*			O
Enabled			C

Factory Reserved				O
Factory Reserved					O
Key * = Default C = Closed (jumper installed) O = Open (no jumper installed)

Figure 2-1

PCBA Jumper Location and Configuration

4092 Cylinder Limitation

On some older BIOS', primarily those that auto-configure the disk drive, a hang may occur when the drive cylinder value exceeds 4096. The 4092 Cylinder Limitation jumper reduces the capacity in the Identify Drive to 4092 – allowing large capacity drives to work with older BIOS'. Use Maxtor's MaxBlast Plus installation software to access the full capacity of the drive.

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