SCSI-2 Fast/Wide Adapter


@8EFC.ADF IBM PS/2 SCSI-2 Fast/Wide Adapter/A
C8EFC.ADF Init file for @8EFC.ADF

193-294 IBM SCSI-2 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 7.1
corv77.exe SCSI-2 Fast/Wide Firmware rev7.7
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

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

Adapter Microcode Protection during Download (TDB) (old)

Possible MCA Interface Chip Problems

SCSI-2 Fast/Wide Adapter
   Adapter Rear
Jumpers on the Fast/Wide
Diagnostic Port
PLCC Socket
PTC Function
LED Flash Codes
Update Corvette Flash
Internal SCSI Connector
External SCSI Connector
   HPDB68 to MCX Adapter
   05H3834 is HPDB68 Only!
Running Wide Devices on Narrow Cables
SCSI Configuration Flexibility
SCSI Device Order
Maximum SCSI Devices Supported
Fast POST Consequences
Maximum Number of SCSI Adapters
Server 85 - Sharing External SCSI DASD Fails
RS/6000 Boot Support
ADF Sections

SCSI-2 Fast/Wide Adapter "Corvette", FCC ID ANO6451280, FRU P/N 92F0160 [P] or 11H3600 [P]

CR1 Motorola MBRD630CT Schottky diode
J2 Mini-C68 SCSI port
J4,5,8 Leave open (not used)
J7 2x3-pin diagnostic header
OS1 40 MHz osc
TR29 PTC (External SCSI bus)
TR30 PTC (Internal SCSI bus)
U1 SCSI microcode 61G3929
U2 SCSI microcode 61G3930
U3 Internal SCSI controller "Cutlass"
U4 AMD N80C186-20 MCU
U5 61G2323 MCA bus iface "Malibu"
U6 External SCSI controller "Cutlass"
U7 PLCC ROM socket (empty)

U1,2 SCSI microcode, Intel N28F001BX-T150 128Kx8 boot block flash memory [P]

U3,6 Internal and external SCSI Controller "Cutlass"
52G9307 (9314) on controllers made from about 9243 to 9340
82G2645 (9352) on controllers made from about 9404 to 9512

SCSI-2 Fast/Wide Adapter Rear FRU P/N 92F0160 [P] or 11H3600 [P]

CR2 Diagnostic LED (flash codes)
CR3 Motorola MBRD630CT Schottky diode
U8,9 89F7000 Term Network, external
U10,11 89F7000 Term Network, internal
U12 TL7705BC Supply-voltage supervisor
U14,19 CXK581000AM-70LL 128Kx8 SRAM

CR1,3 (front, back) Motorola MBRD630CT ("B630T") Schottky diode [P]
Part of the SCSI termination circuit.

Jumpers on Fast/Wide

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.

J4 Grounds pin 33 of the internal SCSI controller U3. Purpose unknown.
J5 Grounds pin 2 of the ext. term. network U8 & U9. Purpose unknown.
J8 Pulls pin 30 (-RP) of the flash dev. U1 & U2 to the "unlock voltage" (VHH = 12 V). This allows programming of the boot block (resembles J6 - Boot Block Enable on Diff. F/W).

Diagnostic Port

2x3-pin header (J7 on FW and Enh. DFW, J2 on DFW).

NCActually connected to +5 V
ALVE (ALIVE)?? (U3 pin 58)
BUR (BURNIN)IBurn-in mode (U6 pin 74)
RXDISerial diagnostic port receive data (U6 pin 47)
TXDOSerial diagnostic port transmit data (U6 pin 58)

The port can be used to access the Serial Console.

PLCC Socket

The empty PLCC socket (U7) is intended for a SCSI BIOS ROM (system BIOS extension). The ROM is not needed as all supported PS/2 machines have SCSI BIOS included in the system BIOS. The RS/6000 line doesn't use a traditional BIOS at all and the SCSI support is part of the AIX operating system.

The pinout seems to match the Atmel PLCC-44 16-bit OTP EPROM series - in particular the AT27C516 (32Kx16) and AT27C1024 (64Kx16) devices.

Pins 40 & 41 - address lines A14 & A15 - are tied to ground. Pin 42 appears to be unconnected (A16 on AT27C2048 & AT27C4096) and pin 43 is tied to Vcc (A17 on AT27C4096, -PGM strobe on all other). This limits the device to 14 usable address lines A0 - A13 (A13 needs confirmation). Therefore the maximum usable ROM area is 2^14 * 2 (16 bit) = 32 KB.

The 4-4 SCSI-2 SE High Performance Adapter has a chip (P/N 52G7507) in the PLCC socket. The 4-4 is the only F/W related SCSI adapter to have the PLCC chip installed. Type unknown.

The empty socket could possibly be used to install a custom BIOS extension ROM or to make the adapter compatible with otherwise unsupported machines.

PTC Function

There is one PTC for the internal SCSI bus and another for the external bus. The PTC protects the SCSI bus from high currents due to shorts on the cable, terminator, or device. It is highly unlikely that the PTC resistor can be tripped by a defective adapter.

A fault (short circuit) causes an increase in PTC resistance and temperature. The increase in resistance causes the PTC resistor to halt current flow. The PTC resistor returns to a low resistive and low temperature state when the fault is removed from the SCSI bus or when the system is powered off. Wait 5 minutes for the PTC resistor to fully cool, then reset.

MF-SM Series - datasheet, archived page

LED Flash Codes

All SCSI-2 F/W adapter versions (Corvette SE, DE, Enhanced/Turbo, and Integrated) have an onboard LED indicator that aids in problem debugging.

At power ON, the LED stays lit until SCSI POST executes (RS6K, system LED=292). If SCSI POST is successful, the LED turns off.

If there is a hardware failure, the LED flashes a failure code. The failing component is identified by LED blinks, a pause, then a repeat of the blinking code again, over and over.

CodeDefinitionProbable Causes
0No error (LED turned off)N/A
180186 ROM Test FailureSCSI Controller
2Local RAM Test FailureSCSI Controller
3FUSE BadDevices/Cable/Term
480186 Peripheral Test FailureSCSI Controller
5Local Transfer Bus (LTB) Test FailureSCSI Controller
6Undefined Error ConditionSCSI Controller
7System Interface Control Chip Test FailSCSI Ctlr/IO Plnr
8Internal SCSI Interface Test FailureDevice/Cable/TERM/Contrlr
10External SCSI Interface Test FailureDevice/Cable/TERM/Contrlr

A blink code of 3, 8, or 10 may indicate a configuration problem like a shorted cable or bad device, or duplicate SCSI addresses on the same bus.

LED stays solidly lit after SCSI POST executes - replace SCSI controller. LED blinks during normal operation. If it's non-periodic, it isn't a problem. During normal operation the device driver may issue a command reset to the adapter, when this occurs you will see the LED blink briefly.

Example: If the LED blinks 8 times, this indicates a bad internal SCSI bus. First, remove the internal SCSI cable from the SCSI Controller. If the problem persists, replace SCSI Controller. If not, add the cable and SCSI devices back (one at a time) until LED again starts to blink.

Update Corvette Flash (from Uli Link over in Germany)

Get REV77.BIN, it is the renamed  - 8EFC3011.77M  from corv77.exe

Run rev71upd.exe It creates a bootable floppy:

REV71    BIN       131,082  01-19-96  6:40p REV71.BIN
AUTOEXEC BAT           720  04-13-03  1:07p AUTOEXEC.BAT
README   TXT           815  10-05-95 10:06a README.TXT
DOWNCORV EXE         2,479  08-31-94  6:16p DOWNCORV.EXE
REV58    BIN       131,082  09-22-93  3:50p REV58.BIN
SCSILEVL COM           928  03-24-93  5:31p SCSILEVL.COM
COMMAND  COM        48,006  10-25-91 12:00p COMMAND.COM
DOWNNEW  EXE         2,479  08-10-94  9:53a DOWNNEW.EXE

Copy Rev77.bin to a:. Edit a:\autoexec.bat:

@echo off
@echo on
downnew rev77.bin   <-- rename the rev71.bin to rev77.bin
@echo off

You can use "downcorv.exe" instead of "downnew.exe" "downnew.exe" checks for flashing only newer firmware into corvette. "downcorv.exe" is even able to downgrade.

If you flash the DOS way, the new firmware level is NOT recognized by AIX. To flash a PS/2 corvette in a RS/6000 rename 8EFC3011.77M to 8EFC0001.77M. Now the firmware level 077 is recognized by AIX. The adapter still will work in a PS/2 and can be downgraded back to 071 or even 058.

Tested with 3 corvettes in RS/6000 C10 and 2 Lacunas. No problems so far. But no problems before flashing, too.

Internal SCSI Connector

This is a "mini-Centronics" plug. The ANSI moniker for it is a "P" plug. 80 pin version seems to be used for SCA drives... Hmm... It used to be you could find many IBM P/2 or RS/6000 cables and you could pick and choose the exact one for your PS.2. Nowadays, there are a lot more HPDB68 SCSI connectors to IBM SCSI controllers.

AMP (Tyco) # 1-557089-2

CHAMP 050,68P A/P RCPT,25 CL CHAMP. 0.050 I Series Interface Connectors
   For VMC Applications: 68-Position   Designed for 30 AWG solid conductors on .064mm (.025") centers.

Obsolete, but old stock available here and there...

TE Connectivity (Molex) # 1734098-7

Champ050 68p A/P RCPT 25CL PB .050 CHAMP Series I 1734098-7
Spec Drawing

Active part.

Molex 71660i # 15-92-3068 1.27mm (.050") Pitch

EBBI 50D - Receptacle, Vertical, IDT 71660i
   30 AWG solid or stranded .025" ribbon cable or laminated discrete wire cable

Status is "Obsolete" and "Replacement: Contact Molex". Odd, all the 071660 series board receptacles are still active.

External SCSI Connector

The peculiar connector seems to be called the "MCX" and is made from pure unobtanium. Manufacturer unknown.

HPDB68 to MCX Adapter FRU P/N 50G0460, Mkt P/N 94G5569

The C68 or MCX port is refreshingly rare. IBM did have some smarts when it made a handy-dandy adapter, "Interposer 68 Ribbon to 68 Socket", P/N 50G0460. Mine is made by Amphenol with a date of 06/97.

Use of this interposer is simple. Use the thumbwheels to fasten the interposer onto the F/W adapter. Screw on the HPDB68 socket. Power on and compute.

05H3834 is HPDB68 Only!

This is an HPDB68 M to HPDB68 F interposer, for MAGSTAR 3570, 3590, and 9406 AS/400. It is a near-miss, where BOTH connectors are HPDB68... No Holy Joy, folks, move along...

"INTERPOSER 68 HIGH TO 68 STANDARD" IBM P/N 05H3834, Amphenol 04/95.

MidrangeWiki - 05H3834

"05H3834 is an IBM part number for a SCSI interposer which was only needed for the old tape/disk controller card feature card #6501. It is a passthrough type connector, with male pins on one side and female pin receptacles on the other side.

The interposer was needed because the pins on the SCSI cables did not make proper physical contact with the #6501 card... ... the interposer has longer male pins than the standard length, as seen on a 61G8324 terminator for comparison."

Running Wide Devices on Narrow Cables

The Corvette automatically terminates it's end of the SCSI bus with termination networks on the back side. However, some user intervention IS required within System Programs.

Uli Link replies:
   Not in terms of termination. You must disable "wide messages" if you connect a wide SCSI device to a wide SCSI controller through narrow cabling. During negotiation both devices agree both can speak "wide". But the cabling cannot. So *no* wide negotiation must happen.This is what disabling the "wide messages" does. If you connect wide SCSI devices through wide cables all works automagically.

Some combinations of Narrow and Wide devices on a Corvette

8EFCh "IBM PS/2 SCSI-2 Fast/Wide Adapter/A" or planar section
"Wide SCSI messages - External"
       <"Enabled">, Disabled
Enable for a wide cable and wide external device. Disabled for a Wide SCSI device attached through a narrow (8 bits wide) external interface cable.

"Wide SCSI messages - Internal"
      <"Enabled">, Disabled
Enable Wide - Internal for a wide cable and at least a wide terminator (or wide device). Disable for a Wide SCSI device attached through a narrow (8 bits wide) internal cable.


SCSI type SCSI-2 Fast/Wide
SCSI bus path / speed 16 bit / 20 MB/sec
I/O bus path / speed 32 bit / 40 MB/sec streaming
I/O features Streaming data transfer
Address parity and data parity
RAID levels None (use software)
Tagged Command Queuing Yes
Processor 80C186 at 20 MHz
Size Type 3 (short)
Channels Two (one internal/one external)
Connectors Two internal SCSI-1 or SCSI-2 cabling
50 pin edgecard and 68 pin mini C68
(only one active);one external C68
Devices supported 7 narrow or 15 wide per adapter
15 on Server 500 on one or two channels
Cache std / max 0 KB / 0 KB (128 byte buffer)

The Corvette is a SCSI-2, 32-bit MCA 40 MB/s Data Streaming bus master adapter with dual SCSI-2 16-bit, F/W channels (one 20 MB/s internal, one 20 MB/s external). The dual bus of the adapter prevents access to internal DASD from the external port and also allows the maximum cable length to be calculated individually for each bus. Data transfer rates for 8 bit SCSI up to 10 MB/s, 16 bit devices up to 20 MB/s.

The Corvette supports SCSI Tagged Command Queuing (TCQ), making it possible to send multiple commands to the fixed disk, and the disk stores the commands and execute each command in the sequence which will give optimal performance. Standard 8-bit SCSI devices are supported using either asynchronous, synchronous, or fast synchronous (10 MBps) SCSI data transfer rates.

SCSI Configuration Flexibility

Systems with the enhanced SCSI device and adapter support allow up to 8 IBM PS/2 SCSI adapters of any type to be installed in a single system. The maximum number of SCSI devices which many be configured in these newer systems has also been increased from 60 to 120.  However, other factors, for example, the type of devices (optical, etc.), cooling requirements, or power consumption of the devices may limit the number for a particular system.

SCSI Device Order

SCSI device logical ordering and hard drive letter assignment (e.g. C:, D:) sequence is determined by the SCSI adapter slot numbers, internal or external SCSI bus connection, and SCSI ID of the connected devices.

Adapters are scanned for SCSI devices beginning with the SCSI adapter in the lowest numbered slot.  Devices connected to the same adapter are logically ordered according to device SCSI IDs in order from 7 to 0 and then from 15 to 8 according to the priority scheme defined by the SCSI standard.  Devices connected to a SCSI-2 Fast/Wide adapter's internal bus connector are ordered logically before devices connected to the external bus of the same adapter.

Maximum SCSI Devices Supported

Wide SCSI devices support 16 possible SCSI ID values. The adapter uses one these values; therefore, the SCSI-2 Fast/Wide adapter can connect up to 15 fast and wide devices internally or externally in any combination using the remaining ID values. Narrow SCSI devices support 8 possible SCSI ID values; therefore, up to 7 narrow SCSI devices can be connected to the internal or external SCSI buses in any combination using the remaining ID values. Wide and narrow devices may be mixed on the same internal/external bus by using the proper combinations of SCSI bus cables, terminators, and/or SCSI connector convertor adapters.

Note: Use of a 8 bit (Narrow) cable forces the controller to default to only 7 devices supported on that port, even if all devices on that cable are Wide.

Fast POST Consequences

Some newer systems also provide a FAST POST option which may be selected from the system configuration menu or from the IBM logo screen. When this option is selected, the system will not check for the presence of newly added SCSI devices unless F1 is also pressed while the IBM logo is displayed. Newly added SCSI devices will not be configured nor will an error occur if the fast post option is chosen as the default. To access the system configuration program, press F1 while the IBM logo screen is displayed to configure the new SCSI device(s) initially.

Maximum Number of SCSI Adapters

Tim Clarke uttered this after a pint of warm beer:
   All **IBM** SCSI CBIOS-flavour (i.e. *not* FD MCS700 OEM) will share IRQ14 and you only need one BIOS ROM enabled to drive multiple adapters. So, for example you *should* be able install (in the same slot-type, please) IBM F+W SCSI-2 "Corvette", IBM SCSI w/cache ("Spock") and IBM SCSI w/o cache ("Tribble") in the same PS/2. No naughties like AHA1640, Storage Dimensions unless you disable their BIOS ROMs and assign a different IRQ.

OS Limits

Not all Microsoft products support multiple IBM SCSI adapters gracefully. W9x cannot handle shared IRQs and will drop into MS-DOS compatibility mode. Win NT handles the shared Interrupts. OS/2, Linux and many UNIX systems support shared Interrupts.

Server 85 - Sharing External SCSI DASD fails

External SCSI DASD expansion shared between two system fails when one of the systems is powered down. Systems affected : 9585 0N* MCA SCSI-2 Fast/Wide controller card.

On the 9585 0N* the trace on the solder (back) side of the planar running parallel below resistor R351 must be cut. On the SCSI-2 F/W controller the trace running next to C30 on the component side of the card must be cut. This trace runs from the fourth pin from the right on the bottom of the larger IC next to the external connector.

On the Corvettes in my possession, some have no trace at all from the fourth pin, nor is there a C30 on the PCB. Others have it. YMMV.

RS/6000 SCSI-2 Fast/Wide Boot Support

SCSI-2 Fast/Wide adapters available for the RISC/6000 are recognized as boot devices on all POWER2 and PowerPC systems. They are not recognized as boot devices on POWER-based models. Any devices attached to a POWER-based model via a SCSI-2 Fast/Wide adapter may be used for storage but cannot be used as a boot device.

SCSI-2 F/W Adapter (4-6, 4-7, 4-C) Boot Support

TypeModelProcessorSCSI-2 F/W
Boot Support
7006AllPowerPC 601/604Yes
7007N40PowerPC 601No (N/A)
7009AllPowerPC 601/604Yes
7010All "Xstation"(various)No (N/A)
701122x,23xPOWER RSCNo
25xPowerPC 601Yes
397POWER2 Super ChipYes
G30,G40PowerPC 601/604 SMPYes
595POWER2 Super ChipYes
J30,J40PowerPC 601/604 SMPYes
R30,R40PowerPC 601/604 SMPYes

ADF Sections @8EFC.adf 4/10/95

I/O Address 
   Each adapter must have a unique I/O address range.
    <3540-3547>, 3548-354F, 3550-3557, 3558-355F, 3560-3567, 3568-356F, 3570-3577, 3578-357F, 3578-357F 

DMA Arbitration Level
   Arbitration level used to transfer data.
   <C>, D, E, 8, 9, A, B, 1, 3, 5, 6, 7 

SCSI Adapter Address (ID)
   SCSI ID of adapter. Usually ID7, unless you have specific requirements.
   Adapter IDs available are: <7>, 6, 5, 4, 3, 2, 1, 0

Move Mode Support
   Enable or Disable Micro Channel Subsystem Control Block Move Mode This is the second mode of SCBA (first is locate mode) which permits the system processor to move the subsystem control blocks to the adapters directly.
   <Enabled> or Disabled 

Wait State Support
   Enable or Disable Bus Master wait states. If the target expansion card is an older card, it may not be able to process commands or data from the busmaster fast enough, and when queried by the busmaster, it replies with "not ready". By inserting a wait state, the slower card has more time to signal "ready". Enabling wait states can slow your busmaster down.
   <Disabled> or Enabled 

Data Parity Exception Handling
   This Adapter can generate and detect data parity on Micro Channel. Data parity must be supported on both ends of an across-the-bus transmission in order for this error detection process to be effective. A data parity enable (-DAPAREN) bus line to the system and other expansion boards is enabled when data parity is being used. If the System does not support Data Parity Exception Handling, this feature will always be disabled.
   <Enabled> or Disabled 

Selected Feedback Return Exception
   Whether a busmaster will report errors detected in the select-feedback-return process. When enabled, the busmaster monitors the selected feedback return and card-selected feedback buslines. The return line tells the master that it's target expansion board is responding properly to being addressed for a read or write operation. If the bus master does not receive this signal (and SFR has been enabled) it may mean that the expansion board is not operating properly or that the signals themselves are not properly traveling across the expansion bus. This error causes the master to immediately halt the transfer in progress and notify the host system of the error using an interrupt.
   Note: The SFR must be ignored for PC compatibility. If the System doesn't support the Selected Feedback Return feature, it will always be ignored.
   <Enabled> or Ignored 

100 ns Streaming Data Transfer Support
   This provides better performance. It will be disabled if the system doesn't support it.
   <Enabled> or Disabled 

Target Mode
   Target mode should be disabled only if this system is sharing SCSI devices with another system and there are more than 15 devices to be shared.  Only 15 devices can be configured on each adapter. When target mode is enabled, this adapter appears as a processor device on the other system and unless you have specialized software that can communicate between the two systems through these processor devices (peer-to-peer communication), there is no advantage in having target mode enabled. When target mode is disabled, this adapter does not appear as a device to the other system, and one more device can be shared by the two systems.  If your system is not sharing any SCSI devices with another system on this adapter, it does not matter whether you enable or disable target mode.
   <Enabled> or Disabled 

SCSI Disconnect
   Disconnect is a SCSI-bus procedure in which a device logically stops communicating with the adapter during certain operations and then reestablishes communication with the adapter when the operation is complete.  Disconnect should not be confused with the 'Presence Error Reporting' option for a device in 'Set and view SCSI device configuration.'

If you are using an operating system that is single-threaded and issues commands to only one device at a time (such as DOS or Win95), disabling SCSI disconnect might result in a slight performance improvement.  If your operating system is multi-threaded (such as OS/2), disabling SCSI disconnect will degrade the performance of the SCSI subsystem.
   <Enabled> or Disabled

Fast SCSI - External
  If Fast SCSI devices are attached externally, enabling Fast SCSI improves performance
  - One external SCSI device enclosure model 3511.
  - Up to three external SCSI device enclosures model 3510.
  - Any external configuration where SCSI cable length isn't > 3 meters.
   <Disabled> or Enabled 

Wide SCSI messages - External
   'Enabled' if external Wide SCSI device attached with WIDE (16 bit) cable.
   'Disabled' if external Wide SCSI device attached with NARROW (8 bit) cable -OR-
       if an external Narrow SCSI device is attached with a NARROW (8 bit) cable.
   Note: "Disabled" applies termination to the High Byte on the adapter itself.
   <Enabled> or Disabled

Wide SCSI messages - Internal
   'Enabled' unless a Wide SCSI device is attached through a narrow (8 bits wide) cable.
   Note: This is almost always using a Wide drive on the 50 pin edgecard connector.
   <Enabled> or Disabled

Internal/External Bus Mode
   'Separate', SCSI devices on external bus connector can have the same SCSI ID setting as other SCSI devices connected to internal SCSI bus connector on the same adapter.

    'Combined', all devices must have unique SCSI ID settings regardless of which SCSI bus connector is used to attach the devices.  Default is 'Separate' unless you are using an operating system device driver that does not support independent operation of the internal and external SCSI buses on the adapter.
    <Separate> or Combined

Note: SCO Unix and Banyan Vines can not recognize devices configured on the SCSI-2 F/W Adapter (DFW as well), when in a 90 /95 level 3 BIOS or higher. This is due to the the internal and external ports being separated. A special version of the SCSI-2 F/W Adapter's ADF (@8EFC.ADF) file is available to allow the buses to be set to a COMBINED state, which overcomes this problem.

Note: I don't know what version this is for, nor do I know if later versions of SCO Unix and Banyan Vines fixed this issue. The last version of the F/W ADF has "COMBINED" as a choice.

System Determined
ROM Address Range
   Address of 32K block of memory assigned to adapter. Only one SCSI Adapter will have the ROM assigned, and any other SCSI Adapter installed will share that address range. 

ESDI Requirements
   If the ESDI adapter is also installed, then the address of the SCSI adapter must be greater than the ESDI adapter address.

Content created and/or collected by:
Louis F. Ohland, Peter H. Wendt, David L. Beem, William R. Walsh, Tatsuo Sunagawa, Tomáš Slavotínek, Jim Shorney, Tim N. Clarke, Kevin Bowling, and many others.

Ardent Tool of Capitalism is maintained by Tomáš Slavotínek.
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