SCSI adapter by Hiroshi Yamashita (old version)
PS/2 SCSI /A ("Tribble")
Short SCSI /A (A/16) (DIP Terminator)
Short SCSI A/16 (SIP Terminators)
2/3 Length SCSI/A (50-pin Header + Card Edge)
Short SCSI A/32 with Cache (DIP Terminator)
Short SCSI A/32 with Cache (SIP Terminators)
2/3 Length SCSI/A 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.
Short SCSI A/16 (DIP Terminator)
P/N 35G2976
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![Front (alt) [P]](/other/img/photo.gif)
P/N 66G1080, FCC ID ANOTPS
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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
U4 33F6910
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U5 SCSI microcode 54G1800
U7 SCSI BIOS Even 92F2244
U8 Intel 80C32GBAA
U9 84F8324 Line Interface
U15 CXK5864BM-10LL 8Kx8 SRAM
Y1 20 MHz xtal
Y2 25 MHz xtal
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U8 Intel 80C32GB - 10MHz microcontroller
as busmaster CPU
RN1 Resistor pack (term.) -
Bourns 4120R-003 221/331 -
Dual Terminator 220 Ω / 330 Ω
RT1 Polyfuse - Littelfuse 100 HG9K
J3 Pads for 6-pin header; Serial
debug/prog. interface. From left to right, the pinout is CHR, ITS, BRN, TXD,
RXD, GND
Short SCSI A/16 (SIP Terminators) P/N 07G3169

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
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U7 OKI 15F7917
U9 33F6715
U10 OKI 33F6910
U11 Adaptec AIC-6250EL
Y1 "125KD" xtal
Y2 "20AKSS1M" xtal
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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.
2/3 Length SCSI/A (50-pin Header) P/N 79F1140

F1 Fuse
J1 50-pin SCSI Connector (90°)
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
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U10 33F6910 M91V034 OKI
U12 33F6715
U20 HM6264ALFP-15T 8Kx8 SRAM
U21 N8032AH MCU
U24 Adaptec AIC-6250EL
U25 15F7914 M91H048 OKI
Y1 20.000 MHz xtal
Y2 "125KD1B" xtal
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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.
Short SCSI A/32 with Cache (DIP Terminator) P/N 35G2818
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F1 Fuse
RN1 Yellow DIP Terminator
U1 84F8324
U2-4,7-9 TC514256AJL-70 256Kx4 DRAM
U5 SCSI BIOS Odd 92F2245
U6 SCSI BIOS Even 92F2244
U10 15F6903
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U11 33F6715
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
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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.
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 Terminators) P/N 07G3063
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F1 Fuse
RN1-3 SIP Terminator (removable)
RN4 SIP Resistor pack (soldered)
U1 84F8324
U2,7 TC51256T-70 256Kx1 DRAM
U3,4,8,9 HM514256AJP8 256Kx4 DRAM
U5 SCSI BIOS Odd 92F2247
U6 SCSI BIOS Even 92F2246
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U10 15F6903
U11 33F6715
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
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2/3 Length SCSI/A with Cache (50-pin Header) P/N 95F4488
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F1 Fuse
J1 50-pin SCSI Connector (straight)
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
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U10 SCSI microcode 64F5984
U11 Intel N80C188
U12 15F6903
U13 33F6715
U15 SCSI BIOS Even 64F4376
U18 OKI 15F7917
U19 SCSI BIOS Odd 64F4377
Y1 20.000 MHz osc
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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.
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.
Long SCSI 32/A with Cache and 2.5" HD P/N 35G3785
![[P]](/other/img/photo.gif)
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
U5 15F6903
U9 SCSI microcode 10G4890
U10 33F6715
U11 Intel N80C188-16
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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
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All chips on the PCB are same with short SCSI 32/A 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 Adapters –
not 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 Adapters –
capable 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 |
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92F2244/45 |
Flat package |
DIP |
No |
66G1080 *? |
16-bit |
Short |
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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):
- 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.
- 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.
- 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.
- 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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