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SCSI-2 Differential F/W

@8EFC.ADF IBM PS/2 Fast/Wide SCSI Adapter (Uses same ADF as SE F/W)
@8EFC.ADF IBM PS/2 SCSI-2 Adapter
   Different name. Missing Separate/Combined Internal/External Bus Mode choice.
C8EFC.ADF Init file for @8EFC.ADF

194-145 IBM SCSI-2 Fast/Wide Adapter/A, SCSI-2 Differential Fast/Wide Adapter/A (PS/2)
ZG94-0165 IBM SCSI-2 Fast/Wide Adapter/A, IBM SCSI-2 Differential Fast/Wide Adapter/A (RS/6000)

rev71upd.exe SCSI-2 Fast/Wide Adapter Firmware Upgrade .71
corv77.exe SCSI-2 Fast/Wide Adapter Firmware Upgrade .77
corvC9.exe SCSI-2 F/W Enhanced Fast/Wide Firmware Upgrade FRU 93H7896 & 52G3380
ibm2.exe F/W and OS/2 2.1 Fix '94 (ibm2scsi.add and ibm2m57.add)
scsi2fw.exe SCSI-2 F/W Support Diskette v2.0
scsi2fw.txt Readme for scsi2fw.exe

SCSIFIX.ZIP A utility to alter the number of sectors for a SCSI drive and convert them to a 3.94GB drive. (thx Bob Eager!)

SPOCK206 IBM SCSI Driver for Windows 95/98 and Windows NT by Unal Z

AN-904 Application Note 904 An Introduction to the Differential SCSI Interface

Possible MCA Interface Chip Problems

Differential SCSI-2 Fast/Wide Adapter
   Rework on 11H7660 Front
   Rework on 11H7660 Back
Enhanced Differential SCSI Fast/Wide Adapter
   Rear of Enhanced DFW
Jumpers on the Fast/Wide
Further Info

Differential SCSI Fast/Wide Adapter

"Corvette Turbo", RS/6000 4-6, FRU P/N 11H3599 (no workee)
"Corvette Turbo", RS/6000 4-6, FRU P/N 11H7660, P/N 06H7274 (workee) (photos by Ryan Alswede)

RN1-3 Removed on RS/6000 systems when a high-reliability configuration is used (one of them there "Y" arrangements illegal to normal SCSI users).

U1,2 SCSI microcode, N28F001BX-T150 128Kx8 boot block flash memory

U8,9 CXK581000AM-70LL or compatible 128Kx8 SRAM

Yellow Termpacks
Differential SCSI uses a standard passive resistor termination. This terminator remains unchanged from the original SCSI-1 standard to the proposed SCSI-3 physical layer. So you might be confused why a newer SCSI adapter uses the older yellow termpacks like the three can Spock.

The SCSI-2 Differential Fast/Wide Adapter/A supports an internal single-ended and an external differential SCSI bus.

FRU 11H3599
   To date, all attempts to get this RS/6000 adapter to work in a PS/2 have failed. Although the chipset is the same as on the Fast/Wide, the rev .71 flash update does not recognize a F/W chipset.

FRU 11H7660
   This FRU with a PLCC socket WILL work with no special poodle faking. Configures fine, flashes to .71, and works like a normal F/W.

Fast/Wide in 8590/8585
   If you don't have a Type 4 complex on a 95A (dual serial/dual parallel), you may not be able to use some features of the Fast/Wide, most notably Internal/External Bus Mode. You need to run SCSI2FW.EXE to update the system partition.

Front 11H7660 DFW Rework

Rear 11H7660 DFW Rework

Rework A comes off the fourth MCA contact.
Rework B comes off the solder pad marked with a V.
Rework C comes off the third pin on the upper left of U23.
Rework D comes off the second pin of U23.

Trace cuts may have been made in addition to the rework wires.

Enhanced Differential SCSI Fast/Wide Adapter

FRU P/N 52G3380 (workee) (RS/6000 4-C)

U1,2 SCSI microcode, N28F001BX-T150 128Kx8 boot block flash memory

U9,10 CXK581000AM-70LL, HM628128BLFP-7 or compatible 128Kx8 SRAM
70 ns needed for zero wait-state MCU operation at 40 MHz

Rear of Enhanced DFW

FRU P/N 52G3380 (workee) (RS/6000 4-C)

U19,21,22,26,27 DS36954 Quad diff. xceiver
U20,25 89F7000 Term Network, SE

DS36954 Quad Differential Xceiver

Total of seven DS36954 are used on the DFW adapter.

From DS36954 datasheet:
   "Five devices can implement a complete SCSI initiator or target interface. Three transceivers in a package are pinned out for data bus connections. The fourth transceiver, with the flexibility provided by its individual enables, can serve as a control bus transceiver."

89F7000 Term Network, SE

These are the same parts used on the Corvette for automatic termination of the internal Single Ended ports.

Jumpers on Differential Fast/Wide

J5 Grounds pin 33 of the internal SCSI controller 82G2645. Not marked - purpose unknown.
J6 Pulls pin 30 (-RP) of the flash dev. U1 & U2 to the "unlock voltage" (VHH = 12 V). This allows programming of the boot block.

The results of shorting the jumpers ranged from no difference, slight performance hit (10% overhead increase) or a system-halting error. Leave them off. RS/6000 documentation says the jumpers are to be left open.

Corvette Turbo Capabilities

The SCSI-2 Differential Fast/Wide Adapter/A is a dual-ported, fast and wide (two bytes wide) SCSI Micro Channel adapter that provides synchronous SCSI bus data rates of up to 20 MB/s. The internal SE port is capable of addressing up to seven SE SCSI devices and the differential external port is capable of addressing up to seven differential SCSI devices, providing a maximum of 14 devices per adapter. The number of physical devices attached to each port is limited by SCSI bus cabling restrictions. The external differential port can support a total cable length of 25 meters (82 feet).

Additional system, subsystem and high-availability connections are also available with the differential system-to-system and Y-cable features.

Corvette vs. Enhanced Corvette Turbo (from William R. Walsh)

Quick testing in the Server 95A upgraded to P180MMX shows a bit of a speed improvement over the standard issue Corvette. Using a Seagate 10,000 RPM SCA hard disk and UZ's "no-LED" driver, I got:

The Enhanced Corvette Turbo shows a CPU utilization of 10.4% compared to the Corvette's 10.1%. Tests were run using the Simpli Software HDTach tool, which was used before during SPOCK-206 NT driver testing.

Further Info

The differential F/W adapter is based on the same general architecture as the single-ended variant.

See the SCSI F/W page for additional information that applies to both adapters.