SCSI Description
Quantum DLT 8000 Tape System
3-7
3.4
SCSI Signals
The following paragraphs define SCSI signals and bus timing values.
3.4.1 SCSI Signal Definitions
Table 3–3 defines the SCSI bus signals.
Table 3–3 SCSI-2 Bus Signal Definitions
Signal
Definition
ACK (acknowledge)
A signal driven by the initiator as an acknowledgment of receipt
of data from a target or as a signal to a target indicating when
the target should read the data (out) lines.
ATN (attention)
A signal driven by an initiator to indicate that it has a message
to send.
BSY (busy)
An OR-tied signal that indicates that the bus is in use.
C/D (control/data)
A signal driven by a target that indicates whether CONTROL or
DATA information is on the DATA BUS. True (low voltage)
indicates CONTROL.
DB(7–0,P) (data bus)
Eight data-bit signals, plus a parity-bit signal that form a DATA
BUS. DB (7) is the most significant bit and has the highest
priority (8 or 16-bit) during ARBITRATION. Bit number,
significance, and priority decrease downward to DB(0). A data
bit is defined as 1 when the signal value is true (low voltage)
and 0 when the signal value is false (high voltage). Data parity
DB(P) is odd. Parity is undefined during ARBITRATION.
DB(15–8,P1) (data bus)
Eight data-bit signals, plus one parity-bit signal, that forms an
extension to the DATA BUS. They are used for 16-bit (wide)
interfaces. DB(15) is the most significant bit and has the higher
priority (but below bit DB(0) during ARBITRATION. Bit number,
significance, and priority decrease downward to DB(8). Data
Parity DB (P1) is odd.
I/O (input/output)
A signal driven by a target that controls the direction of data
movement on the DATA BUS with respect to an initiator. True
indicates input to the initiator.
Also used to distinguish between SELECTION and RESELECTION
modes.
MSG (message)
A signal driven by a target during the MESSAGE phase.
REQ (request)
A signal driven by a target to indicate a request for an
information transfer to or from the initiator. Each byte of data
transferred is accompanied with a REQ/ACK “handshake”. See
also,
ACK.
Summary of Contents for DLTtape DLT 8000
Page 1: ...DLTTM 8000 Tape System Product Manual Nov 10 2003 81 60118 06...
Page 5: ...USER MANUAL STATEMENTS FOR CLASS B EQUIPMENT continued...
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Page 26: ...Table of Contents xxiv Quantum DLT 8000 Tape System...
Page 36: ...About This Manual Quantum DLT 8000 Tape System xxxii...
Page 54: ...General Description and Specifications 1 18 Quantum DLT 8000 Tape System...
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Page 376: ...Appendix A Definition of Vendor Unique Sense Data Information A 4 Quantum DLT 8000 Tape System...
Page 386: ...Appendix C Updating the Firmware C 6 Quantum DLT 8000 Tape System...
Page 396: ...Appendix E Visual Inspection Procedure for DLTtape Cartridges E 8 Quantum DLT 8000 Tape System...
Page 406: ...Appendix G DLT 7000 Emulation Feature G 8 Quantum DLT 8000 Tape System...
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