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S) 2.0 Motherboards
Q) 2.1 Where can I
find a PS/2 motherboard? (Not fully verified 04/24/00)
PS/2 last a long time, but sometimes due to mother nature, the user
or just age the motherboards (planar boards in IBM-speak) fail. These
can be obtained in many places both new and used. Beware that the
price of a new motherboard is steep from IBM. Some third-party dealers
have them much cheaper than in the past. DakTech
(800-325-3238) carries some either new or as good as new form with a warranty.
Check first, their stock varies. True Blue Parts 508-833-2225 (trueblueparts@mindspring.com)
formally Micro Mart has the Model 80-Axx board for only $60.
Q) 2.2 Instead of a
'stock' motherboard can I get a more advanced board?
Speak of the Devil.. Genesis Technology makes a motherboard replacement
for the 55SX/LS which includes a new slot assembly and the motherboard.
Unfortunately, it's ISA.
Reply Technologies sold new PS/2-type motherboards much cheaper than
the IBM versions. These were high priced compared to normal PC-Clone
motherboards, but if you have cash in memory and PS/2 proprietary items
it is cheaper than replacing everything with new ISA/VLB/PCI based equipment.
Also they offered Pentium processors, the ability to use standard SIMMs,
and even VLB. These are still available used and new on www.ebay.com
. The types of motherboards available from IBM are the 486DX2/66 and 486BL2/66,
and almost every 486 type from Reply Technologies. The IBM motherboards
are only available from the Boulder Surplus Parts division and are limited
as they are no longer being made. Also they were made only for the
60, 65SX, 70 and 80.
There is a model 50/50Z and 55SX/LS planar board upgrade to 486SLC2/50
available currently from IBM. Note: these were discontinued in Sept
94 so they are limited, if IBM Direct doesn't have them call Boulder.
There are two versions of Reply's motherboards: the TurboBoard (for
models 30, 50/50Z, 55SX, and 70) and the PowerBoard (for models 25/25-286,
30-286, 50/50Z, 55SX, 56 and 57, and 70). Using the model 70 as the
example, the TurboBoard offers a 486SLC2 25/50 CPU, 387SX FPU socket, 16MB
max using 3 70 ns parity SIMMs, on board 1MB DRAM video, and 3 16 bit slots
(one with video extension). The PowerBoard offers 486DX2/66, 486DX4/100,
or 586/100 with Intel Overdrive socket, 64MB max using 3 70 ns parity SIMMs,
on-board 1MB (2MB upgrade) 64 bit local bus video, two 32 bit and one 16
bit (with video extension) slots. This is not a bad way to go.
There are no more Reply motherboards at Neointeractive. 04/24/00
Q) 2.3 Will a standard
motherboard work in a PS/2?
No...unless you are VERY lucky(and probably the only one in the world).
Most times the screw holes will not even come close, then the slots will
be way off. Even if you got it fastened into your case you would
need a new power supply (which you would have to screw in some how) and
then new floppy drives etc. You are better off selling the system
and starting from scratch.
A hack was done with a PCI clone board into a 9595 case, but
it involved MUCH hacksaw work, installation of a clone power supply, jury-rigged
motherboard mounting (screwholes DID NOT line up) and MUCH duct tape (the
handyman's secret weapon!).
Q) 2.4 What planars
come with cache and are more up-to-date with today's standards?
The model 70 and 80s with a 25MHz processor (8570/8580-Axx) come with
a 64k L2 cache which is very helpful. Benchmarks on a 20MHz model
80 and 25MHz model 80 with the cache showed Dhrystones at 4k for the 20MHz
and at 7.7k for the 25MHz which is a bigger difference than the 5MHz should
give by itself. As a matter of fact a Cyrix DRx2-40 processor in
a 20MHz machine gave only 8k Dhrystones, a cache of some sort should always
be obtained when purchasing a motherboard.
The Lacuna planar 9576 and 9577 systems (on-board S3 video)
have an L2 cache socket that takes either 128KB or 256K COAST modules.
The 9585 -xKx and -xNx models use a similar cache module.
Q) 2.5 Which motherboards
allow/prohibit additional on-board memory?
The following list shows what memory can be added. The difference
of the Max System and Max Mother is what must be installed in the form
of an expansion card.
Factory Max Max
Model
Installed Mother System
--------------------------------------------------------------------
16 BIT
35/40-all
2 16
16
50-021
1 2
16
50Z-031
1 8
16
50Z-061
2 8
16
53
55LS-LE0
4 8
16
55LS-LT0
4 8
16
55SX-031
4 8
16
55SX-041
4 8
16
55SX-061
4 8
16
55SX-081
4 8
16
56
57SX-045
4 16
16
57SX-049
4 16
16
60-041
1 1
16
60-071
1 1
16
65SX-061
2 8
16
65SX-121
2 8
16
65SX-321
2 8
16
32 BIT
70-061
2 6
16
70-081
4 6
16
70-121
2 6
16
70-161
4 6
16
70-A16
4 8
16
70-A21
2 6
16
70-A61
2 8
16
70-A81
4 8
16
70-E61
2 8
16
70 486-B21
2 8
16
70 486-B61
2 8
16
76
77
80-041
1 2
16
80-071
2 2
16
80-081
4 4
16
80-111
2 4
16
80-121
2 4
16
80-161
4 4
16
80-311
2 4
16
80-321
2 4
16
80-A16
4 8
16
80-A21
4 8
16
80-A31
4 8
16
90 XP 386DX20-O0x
859x XP 486/959x Models
90/95 486SX20 xGx
4 64 64
Parity
90/95 486DX33 xKx
8 64 64
Parity
90/95 486DX25 xJx
8 64 64
Parity
90/95 486SX25 xHx
8 64 64
Parity, Single SIMM spt
90/95 486DX2-50 xLx 4
64 64 Parity, Single
SIMM spt
90/95 486DX-50 xMx
4 64 64/256
Parity or ECC
90/95 486DX-50 N/A
4 64 64
Parity (Upgrade T1)
90/95 486DX2-66 N/A 4
64 64 Parity (Upgrade
T1)
90/95 486DX2-66 xNx 4
64 64/256 Parity or ECC
90/95 586-60 xPx
4 64 64/256
Parity or ECC
90/95 586-66 xQx
4 64 64/256
Parity or ECC
90/95 586-90 xYx
4 64 64/256
Parity or ECC
8573 PORTABLE
P70 386-031
2 8
16
P70 386-061
4 8
16
P70 386-121
4 8
16
P75 486-161
8 16
16
P75 486-401
8 16
16
Max mother is what can be physically added to the motherboard.
Max system is what can be added in the form of memory cards. Max
system is also the maximum memory of the mother and expansion card combined.
New information shows that it IS possible to use a memory
expansion card in a 90 / 95 / 85 system, BUT the extra memory is NOT cached
by the L2 cache controller. Any reads will be SLOWER by far than planar
memory.
Q) 2.6 Can I use normal
72-pin SIMMs? 30-pin SIMMs?
You can alter standard 72 pin Fast Page Mode SIMMs by adding
the Presence Detect to them. This involves soldering
a little blob across a few pins. Go to Peter Wendt's site for details.
Q) 2.7 How do I tell
the speed of the PS/2 SIMMs I have now on my motherboard?
Most of the times unless labeled it will be hard. IBM's numbering
system changes all the time and many times the cross-reference can not
be made. I got a SIMM here that has a nice label stating IBM
2M 85 ns P/N 68X6127 FRU 92F0104. Now if that label
were removed I would only have 89X8922 IBM9314 L46056PE on the 18 chips
that are attached to the SIMM, now if someone can make 2M or 85 ns out of
those three numbers I would be impressed as a call to
IBM showed it as not identifiable.
In OS/2 WARP there is a program that tells what is installed and
the speed of the SIMMs. This program is the system information utility.
Although it would be impractical for a large amount of unlabeled SIMMs,
a few can be ID'ed this way.
According to Louis Ohland <ohlandl@charter.net>:
The 9595 Type 4 (possibly type 3) can report in setup on the speed and
architecture (parity or ECC) of each chip by slot...
Q) 2.8 What speed SIMMs
do I need?
Unlike buying clone motherboards, the speed of the SIMMs you should
need will usually be easily found out. For standard IBM, call IBM
and for all other motherboard makers they should include it in their motherboard
docs. Most of the time the 80 ns memory is the most common on the
newer machines. 120 ns was used on the older PS/2s (i.e. 50's and
60's) and most 386s at or less than 25MHz can get by with 85 ns.
If you upgrade to one of the new 486 replacement 386 CPUs you will
probably need 80 ns memory unless stated that it will work with normal system
memory, 70 ns and faster is probably a good idea and should be used as 80 ns
and slower memory is becoming obsolete.
From Louis Ohland <ohlandl@charter.net>:
The 90 / 95 / 85 prefer 70 ns, but will tolerate 80 ns. If you use a mixed
pair of 70 and 80, the memory controller will use both at 80 ns. You can
hack a 60 ns SIMM to work (adding Presence Detect), but the 60 ns speed is
not supported by the BIOS (nor is it a valid value of Presence Detect!),
and the SIMM will be accessed no faster than 70 ns.
Q) 2.9 How good is
MCA and what does it offer?
IBM is pushing the MCA bus again. It is possible to make it as
fast as VLB, it comes close now. The new 700 machines will offer
a dual bus, MCA/PCI which will give the best of both worlds. The
*BEST* thing about MCA is it usually offers the PLUG-and-PLAY everyone
wants, at least in most cases. You simply copy the .ADF files onto
your reference disk then plug the new card in
and turn on your system. The computer will figure out where the
card is and configure it and for once you don't have to set 10 banks of
8 dipswitchs with a pen :). Also it offers the best bus mastering
out there. A MCA card can totally take over all functions of the
CPU and FPU and cause no interference with the rest of the machine, also
a MCA board can have its own CPU to do the work of the peripheral it is
attached. For example lets say you had a MCA Video Toaster type card...it
could be set up to allow you to configure certain options, enter
data, then have it process the data no matter how complex and return
to your normal machine and witness no slowdown at ALL. MCA allows
card functions to be totally independent and self-controlled.
A problem faced by ISA was device addresses, and ISA bus is only capable
of 1024 device addresses while MCA can address 65,280. Also, MCA
has far more grounds along the bus preventing radio emission.
Lastly, MCA can share interrupts while ISA can not.
The speed of MCA is something underestimated by non-PS/2 users.
It is a very fast and quiet (as far as RF interference goes). Some
specs are:
The maximum transfer rates on a 10 MHz MCA
bus:
16 bit MCA 32 bit MCA
Normal transfers
10MBytes/sec 20 MBytes/sec
(adr/data)
Short Burst and Long
Streaming transfers
20MBytes/sec 40 MBytes/sec
(adr/data data data ..)
Multiplex Streaming
(not available) 80 MBytes/sec
(as above and uses the
`idle' adr lines to
transfer data as well,
for a 64 bit transfer)
Matched Memory Cycle
21.3 MBytes/sec
(matched memory cycle
changes the timing of
(32 MBytes/sec w/o
the MCA bus to 62.5
added wait state
nanosec. for a 187.5
at 62.5 Nanosec.
4 byte adr-wait-data
and 40 MBytes/sec
transfer cycle. This
with 50 nanosec
is on a 16MHz model
timing)
80 as an example.)
[Originator: benker@hp-8.cae.wisc.edu]
Since there have been so many discussions about all of this, I'm posting
the OFFICIAL MCA specs. These are direct from IBM. MCA, as
you will notice, has the capability to be faster than even the local bus
technologies with a transfer rate of up to 160MB/sec. Hope
all of this helps.
The basic transfer cycle on the Micro Channel is a minimum of 200 ns
(100 ns for the address and 100 ns for the data which results in five million
basic transfer cycles per second for a device running in burst mode.
As shown in Figure "Basic Data Transfer Mode", a data transfer operation
is done in two steps. First the address for the transfer (either
I/O adapter or memory location) is selected, then up to four bytes of data
is moved across the data buffer.
Depending of the width of the data path (8, 16, or 32 bits) the instantaneous
data transfer rate on the channel would be 5, 10, or 20MB per second.
The matched-memory extension is a modification to the basic data transfer
mode, which can improve the data transfer capabilities between the system
master and channel-attached memory. When supported, it allows the
basic transfer cycle of 200 ns to be reduced.
The DMA controller on the system board requires two basic transfer cycles
to move either 8 bits or 16 bits of data. It moves the data from
the originator to a buffer in the DMA controller and then to the target
device or memory location. Because two cycles are used per 8 or 16
bits of data, the data transfer rate for DMA controllers is 2.5MB or 5MB
per second. For blocks of
sequential data transferred over the Micro Channel, it should not be
necessary to specify the address information more than once. Both
the source and destination devices should update the address for each cycle
by the size of the transferred data. This technique is supported
by the Micro Channel and is known as streaming data mode (or streaming
data procedure). Using streaming data mode with 32 bit transfer,
the effective transfer rate is 40MB per second. The usage of the
address and data buses during a data transfer using streaming data procedure
is shown in Figure "Streaming Data Mode".
When the Micro Channel is running in streaming data mode, the 32 address
lines are only used during the first cycle of the transfer. These
address lines are therefore available for transfer of an additional four
bytes during each following cycle. This mode is called multiplexed
streaming data mode and gives an effective width of 64 bits (8 bytes) for
each cycle. The resulting effective data rate is 80MB per second.
This is shown in Figure "Multiplexed Streaming Data Mode".
PS/2 Model 9595 (and possibly the 8595) can support the 100 ns basic
transfer cycle with the SCSI Fast/Wide adapter rather than the current 200 ns.
With the current cycle the Micro Channel is able to transfer sequential
blocks of data with transfer rates of 20, 40, and 80MB per second.
Systems implementing the faster transfer cycle would be able to reach
transfer speeds of up to 160MB per second. These rates are essential
for advanced function bus masters, which must move large blocks of sequential
data.
Q) 2.10 Which is better,
ISA/EISA/VLB/PCI/etc?
[From: ralf@wpi.wpi.edu (Ralph Valentino)]
[updated: alkemyst@shadow.net 10/23/94]
Here is a quick overview of the various bus architectures available
for the PC and some of the strengths and weaknesses of each. Some
terms are described in more detail at the bottom.
XT bus: Bus originally used in the IBM XT.
8 data bits, 20 address
bits
4.77 MHz
Comments: Obsolete, very similar to ISA bus, many XT cards
will work in ISA slots.
ISA bus: Industry Standard Architecture bus (a.k.a. AT bus)
8/16 data bits, 24 address
bits (16Meg addressable)
8-8.33MHz, asynchronous
5.55M/s burst
bus master support
edge triggered TTL interrupts
(IRQs) - no sharing
low cost
Comments: Ideal for low to mid bandwidth cards, though
lack of IRQs can
quickly become annoying.
MCA bus: Micro Channel Architecture bus
16/32 data bit, 32 address
bits
10-20MHz, up to 40MHz could
be possible, asynchronous
80M/s burst, synchronous
full bus master capability
good bus arbitration
auto configurable
IBM proprietary (not ISA/EISA/VLB
compatible)
Comments: Since MCA was proprietary, EISA was formed to
compete with it.
EISA gained much more acceptance; MCA is all but dead.
EISA bus: Enhanced Industry Standard Architecture bus
32 data bits, 32 address
bits
8-8.33MHz, synchronous
32M/s burst (sustained)
full bus master capability
good bus arbitration
auto configurable
sharable IRQs, DMA channels
backward compatible with
ISA
some acceptance outside
of the PC architecture
high cost
Comments: EISA is great for high bandwidth bus mastering
cards such as
SCSI host adapters, but its high cost limits its usefulness for
Other types of cards. Very commonly used in servers.
VLB: VESA Local Bus
32 data bits, 32 address
bits
25-40MHz, asynchronous
130M/s burst (sustained
is closer to 32M/s)
bus master capability
will coexist with ISA/EISA
slot limited to 2 or 3 cards
typical
backward compatible with
ISA
moderate cost
Comments: VLB is great for video cards, but its lack of
a good bus arbiter
limits its usefulness for bus mastering cards and its moderate
cost limits its usefulness for low to mid bandwidth cards.
Since it can coexist with EISA/ISA, a combination of all three
types of cards usually works best.
PCI: Peripheral Component Interconnect
32 data bits (64 bit option),
32 address bits (64 bit option)
up to 33MHz, synchronous
120M/s burst (sustained)
(240M/s with 64 bit option)
full bus master capability
good bus arbitration
up to 6 peripherals
auto configurable
will coexist with ISA/EISA/MCA
as well as another PCI bus
strong acceptance outside
of the PC architecture
moderate cost
Comments: Combines the speed of VLB with the advanced arbitration
of EISA.
Great for both video cards and bus mastering SCSI/network cards.
VL 2.0: Video Local Bus version 2.0
64 data bits, multiplexing
and data buffering
up to 50MHz
est. 400M/s burst
full bus mastering
good bus arbitration
specification not completed
yet
=Terms=
Auto configurable: Allows software to identify the board's requirements
and resolve any potential resource conflicts (IRQ/DMA/address/BIOS/etc).
Bus master support: Capable of First Party DMA transfers.
Full bus master capability: Can support any First Party cycle
from any device, including another CPU.
Good bus arbitration: Fair bus access during conflicts, no need
to back off unless another device needs the bus. This prevents
CPU starvation while allowing a single device to use 100% of the available
bandwidth. Other buses let a card hold the bus until it decides to
release it and attempts to prevent starvation by having an active card
voluntarily release the bus periodically ("bus on time") and remain off
the bus for a period of time ("bus off time") to give other devices, including
the CPU, a chance even if they don't want it.
16Meg addressable: This limits first party DMA transfers to the
lower 16 Meg of address space. There are various software methods
to overcome this problem when more than 16 Megs of main memory are available.
This has no effect on the ability of the processor to reach all of main
memory.
Backward compatible with ISA: Allows you to place an ISA card
in the slot of a more advanced bus. Note, however, that the
ISA card does not get any benefit from being In an advanced slot, instead,
the slot reverts To an ISA slot. Other slots are unaffected.
The MCA specs at 10MHz show sustained throughput very close to VLB and
20MHz MCA specs should be equal or superior to VLB, however, usually MCA
cards do not operate at these faster speeds of 20MHz.
TIME LINE
8088 8086 286
386
486
586
**
VL2
***
PCI2
*********
PCI1
***********
VL1
*********************************
EISA
***************************************
MCA
*********************************************************
AT bus
*****************
PC bus
1982 1983 1984 1985 1986 1987 1988
1989 1990 1991 1992 1993
Q) 2.11 Will an ISA
card work in an MCA (PS/2) machine?
No, they will not. MCA, unlike EISA and VLB, is not backward compatible
with ISA.Some dual bus cards exist (DCA network card, ATI Ultra 8514/A)
but these cards are specially designed to flip over and use the correct
edge connector. There WAS an ISA to MCA module for the 286 based Gearbox.
Chances are, most 286 Gearboxes were scrapped. So much for hope...
Q) 2.12 How do I enter
the CMOS configuration menu?
If it is possible on your machine it is Ctrl-Alt-Ins after Ctrl-Alt-Del.
If nothing happens when you hit Ctrl-Alt-Ins at the prompt then you must
use the reference disk to change CMOS values.
On the flash BIOS based systems, when the Surepath BIOS
splash screen pops up, press F1.
On IML 90 and 95 systems, at CP 62 the cursor *should*
jump to the top / right position on the screen Press the keys CTRL + ALT
+ INS. The interval for this is pretty short though - only a few seconds.-
all other models show the CP-Codes in the bottom line of the screen. However:
some are not shown logically, during the time the screen is blanked and
the video subsystem is disabled.
On other IML systems, the cursor *should* jump to
the top / right position on the screen on all IML-machines. Press
the keys CTRL + ALT + INS. The interval for this is pretty short though
- only a few seconds. 9556, 9576, 9577
Q) 2.13 What is bus
mastering anyway?
Bus mastering is the ability of the MCA card to directly read and write
to main memory. This allows the CPU do delegate I/O work out to the
cards, freeing it to do other things. If you want a bus mastering
card, you should specifically request it and expect to pay more.
Also not all cards are available in bus mastering form due to the fact
that they do not have to be independent to the rest of the system, and
some because they can't be independent.
You will not see any benefit from busmasters unless
the system is heavily loaded.
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