Japanese SCSI Adapters

SCSI adapter by Hiroshi Yamashita (old version)

16-bit SCSI Adapters w/o Cache
   Short SCSI A/16 (SIP Terminators)
   Short SCSI A/16 (DIP Terminator)
   2/3 Length SCSI/A (50-pin Header + Card Edge)
32-bit SCSI Adapters w/ Cache
   Short SCSI A/32 with Cache (SIP Terminators)
   Short SCSI A/32 with Cache (DIP Terminator)
   2/3 Length SCSI with Cache (50-pin Header)
   Long SCSI A/32 with Cache and 2.5" HD
SCSI Investigation

Content created by Sandy. Edited and new outlines created by Major Tom.


16-bit SCSI Adapters w/o Cache

16-bit busmaster SCSI adapters based around the SCSI Adapter/A ("Tribble") architecture. The main difference is the smaller form factor of the Japanese adapters.

Later SCSI A/16 adapters replace the AIC-6250EL and 15F7917 pair with the 84F8324 SCSI bus controller.

Short SCSI A/16 (SIP Terminators) P/N 07G3169 [P]

RN1-3 SIP Terminator
U1 HM6264LFP 8Kx8 SRAM
U2 SCSI BIOS Even 64F4376 (27C256)
U3 SCSI BIOS Odd 64F4377 (27C256)
U4 SCSI microcode 84F8233 (27C256)
U6 N8032AH MCU
U7 15F7917
U9 33F6715 SCSI MCA iface/BM DMA controller
U10 33F6910 SCSI Data flow controller
U11 Adaptec AIC-6250EL
Y1 "125KD" xtal
Y2 "20AKSS1M" xtal

Short version of uncached SCSI /A with AIC6250EL and old SCSI microcode set.
Long uncached SCSI /A was equipped in PS/55 5570 (analogous to 8580 25 MHz).
I think this short card was an option for 5530-U/V but I'm not sure.

The serial diagnostic port is wired to the external SCSI connector. Specifically, pin 58 - GND, pin 59 - RXD, pin 60 - TXD. The port can be used to access the Serial Console.

Short SCSI A/16 (DIP Terminator)

P/N 35G2976 [P] [P] | [P]
P/N 66G1080, FCC ID ANOTPS [P] [P] | [P]

J1 Internal SCSI Header
J2 C60 External SCSI Port
J3 Pads for 6-pin header
RN1 Resistor pack (term.)
RT1 Polyfuse
U2 SCSI BIOS Odd 92F2245
U3 33F6715 SCSI MCA iface/BM DMA controller
U4 33F6910 SCSI Data flow controller
U5 SCSI microcode 54G1800
U7 SCSI BIOS Even 92F2244
U8 Intel 80C32GBAA
U9 84F8324 SCSI bus controller
U15 CXK5864BM-10LL 8Kx8 SRAM
Y1 20 MHz xtal
Y2 25 MHz xtal

U8 Intel 80C32GB - 10 MHz microcontroller as busmaster CPU.
RN1 Resistor pack (term.) - Bourns 4120R-003 221/331 - Dual Terminator 220 Ω / 330 Ω
RT1 Polyfuse - Littelfuse 100 HG9K

Pads for 6-pin diag. header; From left to right, the pinout is: CHR, ITS, BRN, TXD, RXD, GND. The port can be used to access the Serial Console.

This adapter was sold worldwide with some PS/2 machines.

The short card (with microcode dated 1993 and later) can handle drives >1GB.

The BIOS (92F2244 and 92F2245) is the same as used on the "later" cached SCSI Adapter so it can support IML drives up to 3.94GB.

2/3 Length SCSI/A (50-pin Header) P/N 79F1140 [P] [P] | [P]

F1 Fuse
J1 50-pin SCSI connector (90° header)
J2 50-pin Edgecard connector
J3 External RS/6000 style connector
RN1-3 SIP Terminator 56F8637
U1 SCSI microcode 84F8233
U2 SCSI BIOS Even 64F4376
U3 SCSI BIOS Odd 64F4377
U10 33F6910 SCSI Data flow controller
U12 33F6715 SCSI MCA iface/BM DMA controller
U20 HM6264ALFP-15T 8Kx8 SRAM
U21 N8032AH MCU
U24 Adaptec AIC-6250EL
U25 15F7917
Y1 20.000 MHz xtal
Y2 "125KD1B" xtal

2/3 Length uncached SCSI for 5560-W0. This one has 2 internal connectors, one is 50-pin flat ribbon cable connector and the other is 50-pin edge card connector.

Together with the cached P/N 95F4488 these are probably the only MCA SCSI adapters from IBM that have the standard 50-pin internal header. Both used in various 5560 machines plugged into one of the 2/3 length slots.

The serial diagnostic port is wired to the external SCSI connector. Specifically, pin 58 - GND, pin 59 - RXD, pin 60 - TXD. The port can be used to access the Serial Console.


32-bit SCSI Adapters w/ Cache

32-bit busmaster SCSI adapters based around the SCSI Adapter w/ Cache ("Spock" & "Spock Prime") architecture. The main difference is the smaller form factor of the Japanese adapters.

Later SCSI A/32 adapters replace the AIC-6250EL and 15F7917 pair with the 84F8324 SCSI bus controller.

Short SCSI A/32 with Cache (SIP Terminators) P/N 07G3063 [P] [P] | [P] [P] | [P]

F1 Fuse
RN1-3 SIP Terminator (removable)
RN4 SIP Resistor pack (soldered)
U1 84F8324 SCSI bus controller
U2,7 TC51256T-70 256Kx1 DRAM
U3,4,8,9 HM514256AJP8 256Kx4 DRAM
U5 SCSI BIOS Odd 92F2247
U6 SCSI BIOS Even 92F2246
U10 15F6903 SCSI Cache/data flow controller
U11 33F6715 SCSI MCA iface/BM DMA controller
U12 SCSI microcode 10G4891
U13 Intel N80C188-16
U14 M5M5256BFP-12L 32Kx8 SRAM
Y1 20.000 MHz osc
Y2 32.000 MHz osc
Y3 25.000 MHz osc

Pads for a 7-pin diagnostic SMD connector; From left to right, the pinout is: +5, ITS, BRIN, CHRST, TXD, RXD, GND. The port can be used to access the Serial Console.

Short SCSI A/32 with Cache (DIP Terminator) P/N 35G2818 [P] [P] | [P]

F1 Fuse
RN1 Yellow DIP Terminator
U1 84F8324 SCSI bus controller
U2-4,7-9 TC514256AJL-70 256Kx4 DRAM
U5 SCSI BIOS Odd 92F2245
U6 SCSI BIOS Even 92F2244
U10 15F6903 SCSI Cache/data flow controller
U11 33F6715 SCSI MCA iface/BM DMA controller
U12 SCSI microcode 10G4890
U13 Intel N80C188XL 20
U14 M5M5256BFP-12L 32Kx8 SRAM
Y1 20.000 MHz osc
Y2 32.000 MHz osc
Y3 25.000 MHz osc

This is the Latest SCSI A/32, probably an option for 5551-Rxx. Basically this adapter is capable to handle drive >1G. Unfortunately most of PS/55s (except 9595 and 8595-J) can't handle IML drive larger than 1G with this adapter due to BIOS issue. 8595-Jxx (1S1P planar with Type 3 50 MHz complex) with this adapter can handle HD over 1 GB as IML drive. SCSI ID for IML drive is not restricted to #6 for this combination.

Pads for a 7-pin diagnostic SMD connector; From left to right, the pinout is: +5, ITS, BRIN, CHRST, TXD, RXD, GND. The port can be used to access the Serial Console.

I once fried the F1 fuse when I attached a Rancho's Single/Differential converter. Really got shocked because that was the only one "> 1 GB capable card" I had back then. I trolled around parts shops in Akihabara and got a similar type of tiny chip named "Poly switch". Electrical specification was a bit different but with the chip my card revived.

2/3 Length SCSI with Cache (50-pin Header) P/N 95F4488 [P] [P] | [P] [P] | [P]

F1 Fuse
J1 50-pin SCSI connector (straight header)
J2 External RS/6000 style connector
RN4-6 SIP Terminator 56F8637
U1 Adaptec AIC-6250EL
U2,7 M5M4256AL-10 256Kx1 DRAM
U3,4,8,9 M5M44256BL 256Kx4 DRAM
U5 HM62256LFP-15T 32Kx8 SRAM
U10 SCSI microcode 64F5984
U11 Intel N80C188
U12 15F6903 SCSI Cache/data flow controller
U13 33F6715 SCSI MCA iface/BM DMA controller
U15 SCSI BIOS Even 64F4376
U18 15F7917
U19 SCSI BIOS Odd 64F4377
Y1 20.000 MHz osc

This adapter is an earlier version of SCSI A/32 and was equipped in 5561-W1x/W2x models. SCSI microcode set is 64F4356/57 and it can't handle drive > 1 GB as ID6.

Together with the uncached P/N 79F1140 these are probably the only MCA SCSI adapters from IBM that have the standard 50-pin internal header. Both used in various 5560 machines plugged into one of the 2/3 length slots.

The serial diagnostic port is wired to the external SCSI connector. Specifically, pin 58 - GND, pin 59 - RXD, pin 60 - TXD. The port can be used to access the Serial Console. It's also available on the three internal test points located above the 50-pin SCSI header. Specifically, TP1 - RXD, TP2 - GND, TP3 - TXD.

Long SCSI A/32 with Cache and 2.5" HD P/N 35G3785 [P]

2.5" SCSI HD is mounted on the adapter. The drive is set to ID #6. The stock HD is WDS280 (80 MB).

U1-3,6-8 HM514256AJP8 256Kx4 DRAM
U4 84F8324 SCSI bus controller
U5 15F6903 SCSI Cache/data flow controller
U9 SCSI microcode 10G4890
U10 33F6715 SCSI MCA iface/BM DMA controller
U11 Intel N80C188-16
U12 SCSI BIOS Even 92F2244
U13 SCSI BIOS Odd 92F2245
Y1 20.000 MHz osc
Y2 25.000 MHz osc
Y3 32.000 MHz osc

All chips on the PCB are same with short SCSI A/32 with cache P/N 35G2818 with Yellow DIP Terminator. Just the parts are reallocated on the PCB.


SCSI Investigation

I'm not sure if I'm correct or totally wrong about the following info. I tested and experienced by myself thus I wrote. I can't explain my experience logically 'cause I can't read BIOS or don't have sufficient documentation about PS/55's SCSI feature.

It is told that PS/55's BIOS lacks, unfortunately, support for over 1 GB IML drive. Even if we use 92F2244/92F2245 SCSI BIOS and 10G4890 microcode, PS/55s such as 5580, 5560 and 5551-N can not accept IML drive larger than 1G capacity. Server models like 9595 (Type 4), 8595 (Type 3) and 9585 are capable to run drives > 1 GB as IML and they are basically same with pure PS/2. In another word, BIOS ROM in Japanese localized processor complexes (and planar) are not sufficient to take drives > 1 GB as it's IML drive even though we use SCSI adapters with enhanced SCSI code. We have such nice cards over here but it's true. It's ridiculous and sad.

Group A Adaptersnot capable to handle > 1 GB IML and/or boot drive

P/N Bus Size Equipped BIOS P/N ROM Type Trm. Cache
6451018 32-bit Long 5580-Y 64F4376/77 EPROM None Yes
15F6561 16-bit Long 5570-V 64F4376/77 EPROM DIP No
95F4488 32-bit 2/3 5560-W1 64F4376/77 Flat package SIP Yes
07G3169 16-bit Short 5551-W ? 64F4376/77 Flat package SIP No

Group B Adapterscapable to handle > 1 GB IML and/or boot drive

P/N Bus Size Equipped BIOS P/N ROM Type Trm. Cache
35G2976 * 16-bit Short 92F2244/45 Flat package DIP No
66G1080 *? 16-bit Short 92F2244/45 Flat package DIP No
35G2818 32-bit Short 5551-R ? 92F2244/45 Flat package DIP Yes
07G3063 32-bit Short Option 92F2246/47 Flat package SIP Yes
6451280 32-bit Short Server 61G3929/30 Flash ROM Yes
92G1572 32-bit Long 8595-Jxx 92F2244/45 EPROM DIP Yes

* Not capable to handle partition > 1 GB as a boot drive. Ed. Huh? But the title says "capable".

Flat package. Don't know correct term for the ROM. It's a flat, SOJ type ROM (write-one-time).

Example:

5580-Y with Type A Upgrade complexes (DX2-66), HD; Seagate ST42400N. Can't make system partition on the Seagate even with an adapter listed under Group B. The Seagate drive IDed as 6 off from 35G2818 can't be recognized as valid drive for IML.

If I use a smaller drive with ID=6 and make system partition on it, then change boot order to Seagate 2G in one partition as C, then system works. Here, if I change SCSI /A to listed under Group A, system stops upon booting with error message "Missing Operating System". If I change older type of SCSI /A to newer one again such as 35G2818 or 07G3063, every thing works fine.

If I change Type A Upgrade to Type 3, the Seagate drive off from 35G2818 and 6451280 (both in Group B) works fine as like as usual PS/2 with Type 3 platform. Also I can give SCSI ID other than 6 to ST42400N.

Conclusion (If I'm correct):

  1. Pure PS/55s don't contain SCSI code in their BIOS or lack some important code relating SCSI. Server models (5580 and 5560) may handle drives larger than 1 GB if BIOS ROM could be replaced. IBM Japan had not ever released such BIOS ROMs nor reference diskettes.
  2. SCSI adapters listed in group A can not handle drive larger than 1 GB for IML purpose. Also it can't boot OS even IML drive is smaller than 1 GB and boot order is changed to another drive larger than 1 GB in which OS is installed.
  3. SCSI Adapters listed in group B can handle drive larger than 1 GB for IML purpose only when it is used with PS/2 complexes including PS/55 Type 3. In this case SCSI ID for IML drive is not limited to ID 6. With Japanese Type 1/2 and dx2-66 upgrades, SCSI adapters in group B on 5580/5560 can't do it.
  4. As a matter of fact, 5551-N can not handle drives larger than 1 GB as an IML drive even though it has 92F2246/2247 microcode set on the planar.

Why Big Blue Japan deleted SCSI code from machine BIOS?

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