SCSI /A
Made in Japan

IBM SCSI /A's sold in Japan. Some can't be seen on the PS/2 pages.
Long uncached (Trible) and Long SCSI w/c (Spock, older/newer) are not listed here.

Short SCSI A/16
Short SCSI A/16 (New Microcode)
Short SCSI A/32 with Cache (Yellow Terminator Pack)
Short SCSI A/32 with Cache (SIP Terminator Packs)
Half SCSI/A with Cache (50-pin Flat Ribbon Inner Connector)
Half SCSI/A (50-pin header Connector Type)
SCSI A/32 with 2.5" HD

SCSI Investigation


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

Short length version of uncached SCSI /A with AIC6250EL and old SCSI micro code set.
Long uncached SCSI /A was equipped in PS/55 5570 (analogous to 8580 25 MHz).
I suppose this short card was an optional part for 5530-U/V but not sure.

U1 HM6264LFP
U2 64F4376 (27C256)
U3 64F4377 (27C256)
U4 84F8233 (27C256)
U5-U8 ALS373
U6 N8032AH
U7 OKI 15F7917
U9 33F6715
U10 OKI 33F6910
U11 Adaptec AIC 6250EL
Y1 125KD
Y2 20AKSS1M
RN1-3 Terminator Register Packs

Short SCSI A/16, P/N 35G2976 (there are several P/N for this adapter) [P]
See explanation HERE.


Short SCSI A/32 with Cache (Auto Termination) (P/N 35G2818) [P]

This is the Latest SCSI 32/A, 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.

U1 84F8324
U2/U7 9336HAK, TC514256AJL-70
U3/U8 9336HAK, TC514256AJL-70
U4/U9 9336HAK, TC514256AJL-70
U5 ODD 92F2245
U6 EVEN 92F2244
U10 15F6903
U11 33F6715
U12 10G4890
U13 Intel N80C188XL 20
U14 M5M5256BFP-12L
F1 *
Y1 20.000
Y2 32.000
Y3 25.000
RN1 Yellow DIP Terminator

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.


Short SCSI A/32 with Cache (SIP Terminator Register Packs) (P/N 07G3063) [P]

U1 84F8324
U2/U7 9306HAK (T51256T-70)
U3/U8 HM512456AJP8 (cache)
U4/U9 HM512456AJP8 (cache)
U5 ODD 92F2247
U6 EVEN 92F2246
U10 15F6903
U11 33F6715
U12 10G4891
U13 Intel N80C188-16
U14 M5M5256BFP-12L
F1 Fuse
Y1 20.000
Y2 32.000
Y3 25.000
RN1-3 Register Packs (removable)
RN4 Register (soldered)


2/3 Length Cached SCSI/A (50-pin header Connector Type) (P/N 95F4488) [P]

This adapter is an earlier version of SCSI 32/A and was equipped in 5561-W1x/W2x models. SCSI microcode set is 64F4356/57 and it can't handle drive > 1 GB as ID6.
Probably this is the only one with usual 50-pin flat ribbon inner connector among all of IBM's genuine SCSI /A for PS/2 and PS/55. But there is another one, see below for P/N 79F1140.

U1 Adaptec AIC-6250EL
U2/7 M5M4256AL-10 (ZIP RAM)
U3/8 M5M44256BL (Cache, ZIP RAM)
U4/9 M5M44256BL (Cache, ZIP RAM)
U5 HM62256LHP-15T
U6 ALS373
U10 BIOS P/N 64F5984
U15 64F4376 EVEN
U19 64F4377 ODD
U18 OKI 15F7917
U20-24 ALS45A
U25 ALS244B
F1 Fuse
Y1 20.000
RN1-3 R
RN4-6 Terminator packs
RN7 R
J1 DB50 SCSI Header


2/3 Length SCSI/A (50-pin header Connector Type) (P/N 79F1140) [P]

Not sure about this one. Maybe uncached SCSI for 5560-W0. Got this one recently (2003.05.11). This one has 2 internal connectors, one is 50-pin flat ribbon cable connector and the other is 50-pin edge card connector.

U1 BIOS P/N 84F8233
U2 64F4376 EVEN
U3 64F4377 ODD
U10 33F6910 M91V034 OKI
U12 33F6715
U20 HM6264ALFP-15R
U21 N8032AH
U24 Adaptec AIC-6250EL
U25 15F7914 M91H048 OKI
D1
F1 Fuse
Y1 20.000
Y2 Unknown
RN1-3 SIP Terminators
J1 50 pins SCSI Connector
J2 50 pins Edgecard connector
J3 Extrnal RS6000 style connector


SCSI 32/A with 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).

U1/2 HM514256AJP8
U3/6/7/8 HM514256AJP8
U4 84F8324
U5 15F6903
U9 10G4890
U10 33F6715
U11 intel N80C188-16
U12 92F2244 EVEN
U13 92F2245 ODD
Y1 20.000
Y2 25.000
Y3 32.000

All chips on the PCB are same with short SCSI 32/A with cache P/N35G2818 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 1G 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 Adapters not capable to handle > 1 GB IML drive and/or Boot drive

P/N Size Equipped BIOS P/N ROM Type Term. Notes
6451018 Long, 32-bit 5580-Y 64F4376/77 EPROM None 2)
15F6561 Long, 16-bit 5570-V 64F4376/77 EPROM DIP 1)
95F4480 2/3, 32-bit 5560-W1 64F4376/77 Flat package SIP 2)
07G3169 Short, 16-bit 51-W ? 64F4376/77 Flat package SIP 1)

Group B Adapters capable to handle > 1 GB IML drive and/or Boot drive

P/N Size Equipped BIOS P/N ROM Type Term. Notes
35G2976 Short, 16-bit 92F2244/45 Flat package DIP 1) 3)
66G1080 Short, 16-bit 92F2244/45 Flat package DIP 1) 3)?
35G2818 Short, 32-bit 51-R ? 92F2244/45 Flat package DIP 2) 4)
07G3063 Short, 32-bit Option 92F2246/47 Flat package SIP 2) 4)
6451280 Short, 32-bit Server 61G3929/30 Flash ROM 2) Corvette
92G1572 Full, 32-bit 8595-Jxx 92F2244/45 EPROM DIP 2) 4)

1) Non-Cache
2) With Cache
3) Not capable to handle partition larger than 1G as a boot drive
4) Capable to handle partition larger than 1G as a boot drive

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 dose not contain SCSI code in it's BIOS or lacks some important codes 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 versions. I'm not a BIOS tweaker.
  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 groupe 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 micro code set on the planar.

Why Big Blue Japan deleted SCSI code from machine BIOS?


PS/55 Index