720r101.exe PC720 Reference Diskette v1.01
720d101.exe PC720 Diagnostic Diskette v1.01
720u101.exe PC720 Utility Diskette v1.01
720s101.exe PC720 Support Diskette v1.01
pc720sp.lzh Pentium ODP Flash update for PC720 6860 v1.10
6860ref.lzh Reference Diskette for Pentium ODP 6860 v1.10
6860dig.lzh Diagnostic Diskette for Pentium ODP 6860 v1.11
PC720 PCI/Micro Channel Product Page (6860-J4x/J0x/JZG)
PC720 PCI/ISA Product Page (6869-J4x)
PC720/750 PCI/Micro Channel Product Page (6860-J4G/J0x/JZG, 6886-J04)
PC330/720/750 PCI/ISA Product Page (6873, 6863, 6883-JFx/JAP/JTN, 6887-JSx/J8x)
Official Japanese product pages (archived).
US5765008 Personal computer with riser card PCI and micro channel interface (Google Patents)
1995 IBM PC Series 720: Unboxing (coobird's lab, YouTube)
1995 IBM PC Series 720: Looking inside (coobird's lab, YouTube)
Content created by Sandy. Edited by Major Tom.
PC720 6860 was introduced to the market together with PC750 6886 in 1995.
IBM Japan didn't introduce the Pentium-based PC730 6876 in Japan, instead they
made this unique space-saving 486 desktop model.
The machine has one standard 3.5" bay for a floppy drive, one slimline
CD-ROM drive bay and an opening for two PCMCIA slots.
The PC720 is a hybrid system with one MCA slot, one shared MCA/PCI slot, and
a ISA-like slot for PCMCIA /A exclusively designed for this box.
||None (socket omitted on some)
||8MB (Max 128MB, 32MB x4)
||1MB (Upgradable to 2MB)
||3-Mode (1.44MB/1.2MB/720KB) x1
||PS/55 D/A NI
||PCI or MCA x1, MCA x1
|Small PCI NIC
|PC Card Slot
||Type I/II x2 or Type III x1 (ISA style PCMCIA /A)
|| 360 (W) x 370 (D) x 89 (H), 9 kg
||PC DOS J6.3/V, Windows J3.1
Type JZG was equipped with a PS/55 Display
Adapter/NI-J and DOS J5.02Z (JDOS).
Model 6869 is an ISA version of PC720.
Model 6863 (also ISA) is named as "PC720" but it's a Pentium machine with P-100.
6863 uses same planar with PC750 model 6883 (probably sold only in Japan, planar is
different from that of 6885/6886 or 6887).
DX4 w/ L2 slot: FRU P/N 85G7310, P/N 85G7235
DX2 w/o L2 slot: FRU P/N 85G8297, P/N 85G8263
J4 40-pin IDE1 connector
J5 Power Switch
J6 Pads for 40-pin IDE2 connector
J10 34-pin floppy connector
J11 PSU connector (3.3V)
J12 PSU connector (AT)
J14 CPU Select (SX/DX)
J19 Unknown (default 1-2)
J20 PSU connector (?)
J22 FAN (Solder pads only)
J23 L2 Cache Socket (DX4 models only)
J24 Riser slot
J26 Small PCI slot #1
J27 Pads for Small PCI slot #2
J32 Speaker connector
J34 Volume pot connector
J36 Suspend/Resume connector
J37 Power & HDD LED connector
J38? CR2032 battery holder
J42 Pads for 4-pin jumper
J44 VESA connector
J50 Frequency select (66/50 MHz)
J51 Mouse Enable/Disable
J52 FDD write Enable/Disable
J53 Clear CMOS (1-2: normal, 2-3: clear)
J54 Password Overwrite
J55 CPU voltage select
U7 Socket 3
U16 PC87323VULB Super I/O
U18 OKI M33S0570-013 06H3669
U24 Flash BIOS 85G7319
U40 Unknown (heatsinked)
U41 S3 86C864P-4 Vision864
U42 Unknown (heatsinked)
U45 AvaSem AV9154-? CPU Freq. Gen.?
U53 S3 86C716-MG SDAC
U55,56 DRAM sockets (video)
U57,60 KM416C256BJ-6 256Kx16 DRAM (video)
Y4 osc/xtal for U45?
J2 is silk screened as "IR/PCMCIA". It's
obvious that PCMCIA is meant for a 2nd PCMCIA device which could be installed
at the front end. I've believed for a long time that IBM only planned to
develop such a device but never made it. That was until I got my 6869-J4K (ISA
DX4-100 model which is not listed in my PC Guide Book). J4K has additional
PCMCIA slot just below the FDD bay which you can see in the picture at the top
of this page. And what does "IR" mean? It's likely for some sort of IrDA
device. No clue if it was ever released.
J14 CPU type select
For 486DX set jumper to position 2-3 (default).
For 486SX set jumper to position 1-2.
J50 Output frequency select for programmable IC? (huh?) 1-2: 50, 2-3: 60.
J51-54 Default setting for these jumpers are all 1-2 closed.
J55 CPU voltage select
For 5V CPU close 2x3 jumper blocks near to the PSU connector.
For 3.3V CPU close 2x3 jumper blocks near to the CPU socket.
Planar can take a DX2-66, DX4-100 or PODP5V83. No interposer required to use
3.3V CPU's. In order to use PODP, BIOS should be updated to KOJT66JP. See below.
The PODP Support Diskettes Kit consists of 3 parts:
- 6860ref.lzh Reference Diskette Ver. 1.10
- 6860diag.lzh Diagnostic Diskette Ver 1.11
- PC720SP.lzh System ROM update utility Ver. 1.10A (KOJT66JP)
Note: Win95 support program,
(dead), is not for 6860 but for 6863/6869 and other ISA models. 32bit PCMCIA
driver contained in this archived file is not usable on 6860. It's for
6863/6869 (and it may be for Win95A).
The planar has 4 SIMM slots and takes 4, 8, 16, or 32 MB, 70 ns, FP, parity
Uses the same style 128-pin L2 cache modules
as the Lacuna and
The original module is P/N
85G4865, marked as
"128KB L2 Super Cache". This module can be used for M70/80 PowerBoard. To say
the truth I bought my 1st 6860 in order to get the cache module from it.
The DX2-66 model does not have the cache socket.
S3 Vision864 1 MB (2 MB for J4G model). Win95 recognize the chip with it's
JZG model doesn't use onboard S3 Vision but use a
PS/55 Display Adapter/NI-J together with
pre-installed DOS J5.02/Z (specialized DOS J5.02 for this model).
I've never seen this type of connector in any other PC. IBM Japan made only
2 adapters for this interface:
- SFF PCI Ethernet card, C/R 85G4854, equipped in 6860-J08
- SFF PCI TokenRing card, C/R?, equipped in 6860-J04. I want to see it!
Note: I don't know if it's a world-wide standard
or not, but according to my friend, this connector was introduced as "kogata
PCI" in IBM's leaflet issued when the PC720 was announced. In Japanese,
"kogata" stands for "small" rather than "micro", though these two words are
nearly the same.
Hard Drive Interface
Only one IDE channel is provided. There are solder pads for 2nd IDE
channel on the planar, but even if the 2nd channel could be activated, there is
no room for 3rd IDE drive.
The drive interface is EIDE and it can handle drives larger than 524 MB.
I've used a 2.4 GB drive, and a 6.4 GB Seagate drive with 15 heads. Both worked
well. I've also tried a 8 GB Seagate drive, but it wouldn't detect it.
Hard drive runs in MS-DOS Compatibility Mode Under Win95
Win95 will load "standard IDE/ESDI hard disk controller" with configuration
#1 which has IRQ value fixed to 15. Change the configuration to #0 which has
IRQ 14, all drives will work properly.
All models except for JZG use the same Riser Card which has 1x PCI/MCA
shared slot, 1x MCA slot, and 1x ISA style slot for 2-slot PCMCIA/A.
The Riser Card for JZG doesn't have a PCI slot but it has one more MCA bus
slot for PS/55 Display Adapter /J located under connector J6 (opposite side of
PCI slot J5).
The outline below is for models other than JZG.
MCA/PCI Riser FRU P/N 85G7333, P/N 85G2105; FRU P/N 85G8245, P/N 85G8243
MCA/PCI Riser Front
J3,4 32-bit MCA slot
J5 32-bit PCI slot
U6 06H5425 PCI-MCA bridge?
U8 10G7808 DMA Controller
Y1 24.0000 MHz osc
U6 06H5425 PCI-MCA bridge? Blue CQFP-272
w/ exposed die. Also used on the PC 730/750 MCA riser and
PC Server 720 planar.
MCA/PCI Riser Back
J1 3-pin jumper (default 1-2)
J6 ISA-style slot for PCMCIA /A
J7 Battery connector (NVRAM?)
J8 Pads for 2-pin jumper
J9 PSU connector
U14 Dallas DS1210S NVRAM controller
U15 M91S028AT OKI/06H6468 (LQFP-100)
U16 06H4542 (PQFP-160)
U17 LH5168N-10L 8Kx8 SRAM (NVRAM?)
J1 3-pin jumper (default 1-2). Possibly
to Enable/Disable PS/55 display adapter?
2-Slot PCMCIA Adapter FRU P/N 85G7334, P/N 54G0547
F1-4 PPTC fuse
2-slot PCMCIA /A with ISA style connector is equipped in all models. ISA
models (6869 and 6883) also use same adapter.
Win95 built in driver can't handle this adapter properly on MCA models but
the very same adapter installed in ISA models can be used without any problem
under Win95B or Win98. I tested a driver for Win3.1 "PC Card Director" on my
6860-J4G and I found it could handle modem card. I've been using a 28.8Kb
Double Jack Modem Card under Win95B. PCMCIA device is not seen under Device
Manager, but the card securely detected in PC Card Director. I don't know if
other cards such as NICs or SCSI PCMCIA can be used.
6860 has a very unique PSU. The cooling fan will slow down if the total
system power is lower than 50W, and will stop to spinning completely if bellow
30W. Thus the cooling fan usually stays idle.
When I got the 6860 I've immediately noticed that the fan wasn't running at
all. As I didn't know about this unique feature I thought there must be some
fault on the circuit board of the PSU. I disassembled PSU and soldered 12V line
directly to the fan assembly. Only latter on have I learned about this unique
function. The jumper wire is still there... Some machines have input AC voltage
selector. Mine has a "fan mode selector", summer mode with direct connection
and winter mode with original connection.
Mine works fine under DOS. But under Win95B it usually freeze at start up
after the Win95 logo appears on the screen. I solved this symptom by modifying
MSDOS.SYS to have a start up menu with default boot for Win95 after 60 seconds
of delay time to boot. Maybe mine needs some delay for stable DC output for
planar, a hard drive and a CD-ROM. I'm sure that this symptom is not related to
the above mentioned fan cable modification, 'cause I have the same problem even
when I switch back to the original cable connection.
Maximum: 70 W
Typical: 40 W
A genuine optional 2x speed CD-ROM (you can see it in the picture at the top
of this page) is # 85G7285. I have a 4x slim drive for Toshiba laptops.
6860 is not an IML machine, but it does support service partition (reference
partition?). My 6860 takes long time till the "Set Configuration" page comes on
the screen when I boot the system with the Reference Diskette. It stays quiet
while it reads configuration files as if the system froze. But from service
partition stored on the hard drive it goes straight into configuration