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PA-RISC SCSI

SCSI bus

The below table lists some variants of the SCSI bus as found in PA-RISC computers.

SCSI buses in PA-RISC computers
SCSI Clock Width Data rate
(max)
Devices
(max)1
Signals2 Length
(max)
Connector
Narrow SCSI 5 MHz 8-bit 5 MB/s 7 SE 6m 50-pin
Fast-Narrow SCSI 10 MHz 8-bit 10 MB/s 7 SE 3m 50-pin
HVD 25m
Fast-Wide SCSI 10 MHz 16-bit 20 MB/s 15 SE 3m 68-pin
HVD 25m
Ultra-Narrow SCSI 20 MHz 8-bit 20 MB/s 7 SE 1.5m 50-pin
LVD 12m
HVD 25m
Ultra-Wide SCSI 20 MHz 16-bit 40 MB/s 15 SE 1.5m 68-pin
LVD 12m
HVD 25m
Ultra2-Wide SCSI 40 MHz 16-bit 80 MB/s 15 LVD 12m 68-pin
Ultra160 SCSI 40 MHz 16-bit 160 MB/s 15 LVD 12m 68-pin
Ultra320 SCSI 80 MHz 16-bit 320 MB/s 15 LVD 12m 68-pin
  1. Excluding the SCSI controller
  2. Signalling:
    • SE - Single-Ended
    • HVD - High-Voltage Differential
    • LVD - Low-Voltage Differential

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SCSI chipsets

A listing of the common SCSI chipsets used in some of the PA-RISC workstations and servers from HP. These chips were both integrated into the main logic of these systems or available on plug-in cards.

SCSI chipsets used in PA-RISC computers
Chipset Speed Width Data rate Bus
53C700 Narrow 5 MB/s GSC
53C710 Fast Narrow 10 MB/s GSC
53C720 Fast Wide 20 MB/s GSC
53C875 Ultra Wide 40 MB/s PCI
53C896 Ultra2 Wide 80 MB/s PCI

53C700

The 53C700 is the primary SCSI controller of the very early PA-RISC workstations with ASP chipset.

Features

Used in

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53C710

The NCR 53C710 is the primary SCSI controller used in early HP 9000s. It was integrated in the LASI chipset as a macrocell as well.

Features

Used in

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53C720

The NCR 53C720 was the secondary SCSI controller used in the early HP 9000s for the attachment of an Fast-Wide (16-bit) SCSI-2 bus, utilizing HVD signalling. It was either controlled by the ASP2 chipset or interfaced to the GSC bus through a chip named Zalon.

Features

Used in

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53C875

The Symbios Logic/LSI 53C875 is the chip that provides the single Ultra-Wide SE SCSI channel on some of the newer PA-RISC workstations.

Features

Used in

References

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53C896

The Symbios Logic 53C896 SCSI ASIC is the chip used on some of the newer PA-RISC workstations and servers to control their storage I/O buses. This ASIC includes two 53C895-equivalent cores to control the two internal channels separately.

Features

Used in

References

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SCSI Adapters

SCSI adapters (HBAs) for the various expansion buses found in PA-RISC systems.

EISA

SCSI adapters for the EISA bus.

EISA SCSI adapters for PA-RISC computers
Part-no. SCSI type Signalling1 Boot HP-UX
A2679A Fast-Narrow SE no 9.0-11i/32-bit
25525A Fast-Narrow HVD 8.05-10.20
25525B Fast-Narrow HVD 8.05-11.0/32-bit

GSC

SCSI adapters for the variants of the GSC bus.

GSC SCSI adapters for PA-RISC computers
Part-no. GSC formfactor SCSI type Signalling1 Boot HP-UX
A2874-66005 EISA Fast-Wide HVD yes 9.05/11.0
A2969A HSC Fast-Wide HVD yes 10.01-11i
A3644A2 HSC Fast-Wide HVD 10.20-11i
A4107A EISA Fast-Wide HVD 9.05-11i/32-bit
A4268A GSC-M Fast-Wide HVD yes 9.05-11.0/32-bit

HP-PB

SCSI adapters for the HP-PB bus.

HP-PB SCSI adapters for PA-RISC computers
Part-no. SCSI type Signalling1 Boot HP-UX
27251A
28655A Fast-Narrow SE yes 10.01-11i
28696A Fast-Wide HVD yes 10.01-11i

PCI

SCSI adapters for the PCI bus.

PCI SCSI adapters for PA-RISC computers
Part-no. SCSI type Signalling1 Boot HP-UX
A4800A Fast-Wide HVD yes 10.2-11i
A4974A Ultra-Wide SE yes 10.20-11.0
A4976A Fast-Wide HVD yes 10.20-11.0
A4999A Ultra2-Wide LVD yes 10.20-11.0
A5159A Fast-Wide HVD yes 10.20-11i
  1. Signalling:
    • SE - Single-Ended
    • HVD - High-Voltage Differential
    • LVD - Low-Voltage Differential
  2. This card is only supported in the T-Class

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