Maxtor ATLAS 10K III Manual download pdf (Page 322)

Quantum Atlas 10K II Ultra 160/m SCSI Hard Disk Drives B–1

Appendix B

SCSI REFERENCE INFORMATION

Appendix B provides information about SCSI bus timing, SCSI signal states, SCSI bus

conditions, and SCSI message format and supported SCSI messages. Information in this

appendix covers both SCSI-2 and SCSI-3 interfaces. Note that this information is general in

nature, and is not specific to the ATLAS 10K II disk drive. It is provided as a reference only.

B.1 SCSI-2 Bus Timing

Table B–1 provides timing values and definitions for SCSI-2 SCSI bus signals.

Table B–1 SCSI Bus Timing Values -- ANSI SCSI-2 Standard

Timing Description Value Description

Arbitration Delay 2.4 µs Minimum time a SCSI device waits from asserting

BSY for arbitration until the DATA BUS can be

examined to see if arbitration has been won; there

is no maximum time.

Assertion Period 90 ns Minimum time a drive asserts REQ while using

standard synchronous data transfers; also, the

minimum time that an initiator asserts ACK while

using standard (slow) synchronous data transfers.

Bus Clear Delay 800 ns Maximum time for a SCSI device to stop driving

all bus signals after:

1. BUS FREE is detected.

2. SEL is received from another SCSI device

during ARBITRATION.

3. Transition of RST to true.

For condition 1, the maximum time for a SCSI

device to clear the bus is 1200 ns (1.2 µs) from

BSY and SEL first becoming both false.

If a SCSI device requires more than a bus settle

delay to detect BUS FREE, it clears the bus within a

bus clear delay minus the excess time.

Bus Free Delay 800 ns Maximum time a SCSI device waits from its

detection of BUS FREE until its assertion of BSY

when going to ARBITRATION.

Bus Set Delay 1.8 µs Maximum time for a device to assert BSY and its

SCSI ID bit on the DATA BUS after it detects BUS

FREE to enter ARBITRATION.

Bus Settle Delay 400 ns Minimum time to wait for the bus to settle after

changing certain control signals as defined in

protocol definitions.

1 2 ... 317 318 319 320 321 322 323 324 325 326 327 ... 370 371

No comments

Maxtor ATLAS 10K III Manual Page 322