Specifications

PRODUCT DESCRIPTION
2 – 14
JUMPER CONFIGURATION J50 J48 J46 J44 J42
Master/Slave
Only drive in single drive system*
Master in dual drive system*
Slave in dual drive system
J
J
O
Cable Select
Disabled*
Enabled
O
J
4092 Cylinder Limitation
Disabled*
Enabled
O
J
Factory Reserved
O
Factory Reserved
O
Key
*
= Default
J
= Jumpered
O
= Open
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'. A software driver is required to access the full capacity of the drive.
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.