1)@DonutKing
Thank you for the information! (:

2) Strange thing, I ran my Shuttle HOT 433 Motherboard this morning (chipset: UMC 8881F 9521-BTS) and discovered that it works correctly with EDO memory! I had flashed bios to 433AUS33.

However my another motherboard based on UMC chipset (GA-486am/s) equipped with an UMC8881F 9523-BCT chipset doesn't want to work with EDO memory. So maybe this is only bios dependent and marks on chipset aren't as important as we previously thought..? People, what do you think about this? (:

Can you type out all the markings on your UMC northbridge and southbridge chipsets?

Do you have a HOT Shuttle 433 rev. 4? Rev 4 supports EDO. I suspect your chipset reads something like UMC8881F-Exx, the E is for EDO. How'd you land a rev 4 board? I'd like to get my hands on one. I only have rev 1-3 which is Cyrix 5x86 flakey. Unfortunately, the Rev4 boards only have 4 cache DIP sockets, thereby supporting up to 512KB cache only.

Check to see if your ps/2 mouse port connector works. I was never able to get it working on rev 1-3.

AMI BIOS's usually let let you set write-thru cache, so w/512KB cache, you'd be able to cache up to 128 MB of RAM.

Can you type out all the markings on your UMC northbridge and southbridge chipsets?

Do you have a HOT Shuttle 433 rev. 4? Rev 4 supports EDO. I suspect your chipset reads something like UMC8881F-Exx, the E is for EDO. How'd you land a rev 4 board? I'd like to get my hands on one. I only have rev 1-3 which is Cyrix 5x86 flakey. Unfortunately, the Rev4 boards only have 4 cache DIP sockets, thereby supporting up to 512KB cache only.

I have also rev 1.x-3.x motherboard! (: Here you are all the markings from chipsets:

northbridge:
UM8881F
9521-BTS
124040

southbridge:
UM8886AF
9536-AYS
N503B6

Check to see if your ps/2 mouse port connector works. I was never able to get it working on rev 1-3.

Sorry, I don't have PS2 cable connector. If I had one I would gladly test it for you.

AMI BIOS's usually let let you set write-thru cache, so w/512KB cache, you'd be able to cache up to 128 MB of RAM.

Thank you for your advice! I used to use 512kB cache on this motherboard for a long time but it was set to write-back mode and I had installed 64MB of RAM.

BTW
Have you ever seen award bios on Shuttle HOT-433? If no, here you are some screens:

EDIT:
I have retested all my UMC based motherboards, the results are:

my second HOT-433 1.x-3.x
northbridge UM8881F
9524-BTT
126380
southbridge UM8886AF
9520-AYA
N408D6
BIOS 433AIP16
EDO support YES

my third HOT-433 1.x-3.x
northbridge UM8881F
UM8881F
9525-BTA
125870
southbridge UM8886AF
UM8886AF
9536-AYS
N509F5
BIOS 433AIP16
EDO support YES

my fourth HOT-433 1.x-3.x
northbridge UM8881F
UM8881F
9525-BTA
125880
southbridge UM8886AF
9540-BYS
R521B0
BIOS 433AUE23
EDO support YES

GA-486am/s rev 2.1A
northbridge UM8881F
9516-BTO
123800
southbridge UM8886AF
9520-AYT
N407D5
BIOS JUNE 1995
EDO support NO

GA-486am/s rev 2.21
northbridge UM8881F
9523-BCT
N43037
southbridge UM8886AF
9540-BYS
R530C1
BIOS 7 NOVEMBER 1995
EDO support NO

ECS UM8810PAIO rev 2.1
northbridge UM8881F
9521-BCT
N42648
southbridge UM8886F
9520-EYS
R40360
BIOS VBS1.11PH
EDO support YES

Last two motherboards have similar signing on northbridge "BCT".The important thing is that one before last motherboard in contrast to last motherboard doesn't support EDO memory!

I admit, I haven't seen an AWARD-based 433, and I've had 4 AMI-based ones in the past. Would you mind uploading an image of the top and bottom of the motherboard?

You even have the option to change L2 to WT! I don't see the EDO option in the BIOS. The 433 manual specifically states that it needs to have -Exx in on the northbridge to support EDO. What led you to the conclusion that EDO RAM works with these? Are you sure you didn't test it with FPM RAM? Sometimes, EDO ram will work for the short-term in motherboards that do not support it, but the system will eventually crash.

The BIOS date is a bit old, July 1995. I suspect a lot of the Cyrix 5x86 enhancement features will not work well on this motherboard. Check for a BIOS update. With my 433 and AMI BIOS, the lack of Cyrix 5x86 support was one of the reason's its been in the computer junk drawer for 10 years.

Now where can I get one of these to test? Are there more?

Now where can I get one of these to test? Are there more?

It is just a plain Shuttle HOT-433 1.x-3.x.

I bought it with AMI BIOS and then flashed to award. Here you can find necessary award bios file:
http://ftp.gwdg.de/pub/misc/mainboards/ftp.sp … /433/433B10.ZIP
To flash from AMI to award I used FLASH465 which is included in this archive:
http://ftp.gwdg.de/pub/misc/mainboards/ftp.sp … /433/433B33.ZIP
(In turn to restore AMI bios I used AWD52B).

The BIOS date is a bit old, July 1995. I suspect a lot of the Cyrix 5x86 enhancement features will not work well on this motherboard. Check for a BIOS update. With my 433 and AMI BIOS, the lack of Cyrix 5x86 support was one of the reason's its been in the computer junk drawer for 10 years.

You are right but this is probably the first and last award bios update for this mobo. Cx5x86 is correctly recognized by BIOS but am5x86 not - I ran it at 133MHz and bios post screen reported 100MHz, when I ran CPU at 160MHz bios reported 120MHz. Also this bios doesn't solve problem with LINBRST on cx5x86 - when I set this option computer froze.

What led you to the conclusion that EDO RAM works with these? Are you sure you didn't test it with FPM RAM? Sometimes, EDO ram will work for the short-term in motherboards that do not support it, but the system will eventually crash.

I'm sure it is EDO memory:
1) When I put this module in BIOSTAR mobo bios reported "EDO DRAM installed!"
http://img832.imageshack.us/img832/558/img1195yc.jpg
2) FIC PIO-2 that officially support only FPM memory doesn't want to work with these modules.
3) Memory module has small sticker with "EDO" inscription (circled on picture).
4) I have checked memory chip datasheet: "MT4C4M4E8DJ - 4 MEG x 4 EDO DRAM - Micron Technology".

Is it possbile that EDO memory is unofficially supported by all UM8881F chipsets and officially only by -Exx revisions..?

Regards! (:

Just looking at the date stamp on your north/southbridges, your board is half a year newer than mine. Thanks for the AWARD files, I'll check it out since my 433 is flakey. My board has an all plastic ZIF handle, while yours looks to be metal. Also, I didn't see an option in the AWARD BIOS for enabling the PS/2 mouse connector, as in the AMI BIOS. I've never been able to get the connector working though.

Do you happen to know what other Cyrix features do not work on this board?

The biggest advantage of this board is the ability to use 1 MB of WT cache to cache all 256 MB of RAM. The disadvantage is no working PS/2 port.

@feipoa
I have tested combo HOT-433 + Cx5x86 100MHz (step 1 rev 3) with following settings enabled (all my dostests work correctly):
BTB=on
FP_F=on
LSS=off
WT1=on
USE_WBAK=on
DTE=on
MEM=on
BWRT=on

Here you are debug output from 5x86.exe program:

Performance control register:
RSTK_EN: Return stack disabled
BTB_EN: Branch target buffer enabled
Loop_EN: Prefetch buffer flush disabled
* All instructions stalled to serialise, disabled
* Locked misalighned load reordering disabled
* Reserved bit 5 disabled
* BTBT: BTB Test register disabled
LSSER: Load store serialise is disabled. Reorder enabled

Configuration control register 1:
USE_SMI: SMI and SMADS pins enabled

Configuration control register 2:
WRTBP: Writeback pins enabled
Lock_NW: NW bit locked
WT1: Write through region one, enabled
BWRT: Burst write enabled
SUSP: Suspend pins enabled

Configuration control register 3:
SMI_LOCK: SMM bits unlocked
NMI_EN: NMI disabled during SMM
LinBRST: 1 + 4 mode (Intel)
SMM_Mode: SL compatable
Map_EN: bit 0 disabled
Map_EN: bit 1 disabled
Map_EN: bit 2 disabled
Map_EN: bit 3 disabled

Configuration control register 4:
MEM_BYP: Memory read bypassing, enabled
DTE_EN: Directory table entry is cached
FP_FAST: NPU fast exception reporting enabled
IORT: I/O recovery time = no clock delay

CR0 register:
NW: 0
CD: CPU cache is enabled
PG: Paging mode is enabled

Device identification register 0:
Cx5x86 3x clock

Device identification register 1:
Device stepping 1
Device revision 3

It seems that only LINBRST setting is problematic - after enabling it system froze.

BTW
Thank you for your advices about cx5x86 enhancement features.

That's pretty good for the HOT-433. I suspect that you will need to disable BWRT for Windows though.

I have some SGS Thomson Cyrix 5x86-100's from early 1996 that I want to plug in. So far, I've only seen Stepping 0/Revision 5 and Stepping 1/ Revision 3 cpus. Even the 5x86-100/4X I have with 1996 date is Step1/Rev3.

feipoa wrote:

The disadvantage is no working PS/2 port.

You know that there must be a 8042 installed in order to use the PS/2 mouse function !?

I was not aware of this. Have you installed an 8042 keyboard controller chip into a HOT-433 rev 1-3 and were able to get the PS/2 port working correctly?

For the 8881/8886 chipset, a Biostar MB8433-UUD is able to work with the PS/2 port without such a controller. Do you know why the HOT-433 needs the i8042 and the MB8433 does not? Does it have a more comprehensive Super I/O?

feipoa wrote:

I was not aware of this. Have you installed an 8042 keyboard controller chip into a HOT-433 rev 1-3 and were able to get the PS/2 port working correctly?

I never tried this because of the odd connector. Do you know the correct pin assignment ?

feipoa wrote:

For the 8881/8886 chipset, a Biostar MB8433-UUD is able to work with the PS/2 port without such a controller. Do you know why the HOT-433 needs the i8042 and the MB8433 does not? Does it have a more comprehensive Super I/O?

Since these boards use the same I/O chip (UM8663AF/BF) I don't think that's the reason.

I have a HOT-433 rev 1-3. Under the microcontroller DIP socket, it has printed "8742", not 8042 as in the rev.4 manual. Wiki refers to the 8742 as "Universal Peripheral Interface, EPROM version." Do you have an existing HOT-433 with the 8742 microcontroller in place? If so, can you type out the markings on it? Does your HOT-433 have the PS/2 external connector, or just the internal one?

There is also an empty DIP socket between two ISA slots that has printed on the motherboard, "7406." It has 14 pins and is a HEX inverter. Is this also needed by the motherboard for PS/2 operation?

The PS/2 pin-out for rev 1-3 is one of these two possibilities:
_____
|1 6 |..........| . . . .|
|2 7 |..........| K.B. |
|3 8 |..........|_____|
|4 9 |
|5 10 |

2 = CLK
3 = Vcc
6 = GND
10 = DATA

OR

2 = DATA
3 = Vcc
6 = GND
10 = CLK

I am sure about the locations of GND and Vcc, and that pins 2, 3, 6, and 10 are used.

EDIT: Another question about the 8742: Since it is a programmable microcontroler, would we need an 8742 that was programmed specifically for the HOT-433? Otherwise, would we need to crack our brain to figure out which input and outputs are needed and program the 8742 ourselves?

I played a bit around and discovered some facts:

The only Bios version to support PS/2 function is 433AUS26.
I inserted an AMIKEY-2 chip and a 7406 chip into the corresponding sockets.
The presence of the 7406 chip gives "KB/interface error" no matter if the Amikey-2 chip is plugged in or not.
With and without the Amikey-2 chip the keyboard-LEDs light up, but the keyboard does not work, it appears no error message though.

I noticed some hard wired jumpers (JP4, JP5, JP7) next to the keyboard controller socket. I know that some other 486 boards offer to change between external and internal keyboard controller by switching some jumpers. Maybe it is also the case here ?

Did you try changing the directions of both the 7406 and AMIKEY-2? The pin I/O numbers may be specific to certain functions.

Did you flash to BIOS 433AUS26? The BIOS on my HOT-433 has an option to enable/disable the Mouse, but I've never been able to get it working.

Your findings are quite discouraging. Is the AMIKEY-2 an 8742? What motherboard did you get it from?

feipoa wrote:

Did you try changing the directions of both the 7406 and AMIKEY-2? The pin I/O numbers may be specific to certain functions.

Did you flash to BIOS 433AUS26? The BIOS on my HOT-433 has an option to enable/disable the Mouse, but I've never been able to get it working.

Your findings are quite discouraging. Is the AMIKEY-2 an 8742? What motherboard did you get it from?

Yes, i flashed from 433AUS2C (no mouse related options) to 433AUS26.
I think that all keyboard controllers on mainboards are 8742 compatible.
What do you mean with "changing directions" ?

Rotate the 7406 180 degrees and reinsert. I haven't yet looked at the spec sheet, but the pins may not be symmetric.

Comparing the chips of a Biostar MB8433-UUD v3.1 and a Shuttle HOT-433, I see that neither of them have a 7406, 8742, or 8042. The Biostar has PS/2 mouse support. I've been using it for years, so I can say that it works. I cannot identify any chip from the IC list below that would be a dead giveaway for why the HOT-433's PS/2 port is non-functional. Perhaps PS/2 support wasn't properly implemented in the older UMC chipsets, or for whatever reason Shuttle never finished implementing it in the BIOS.

Has anyone had success getting the HOT-433 v1-3 PS/2 port functioning?

Biostar MB8433-UUD v3.1:
UM8881F/9639-EYA (northbridge)
UM8886BF/9640-FXA (southbridge)
UM8663BF/9614-BXS (Super I/O)
UM8667/9640-O (supplement to Super I/O -- PS/2 Mouse driver? Other UMC, PCI-based 486's which do not have PS/2 mouse support share all other ICs in common, except for this one)
UM9515-01 (Phase lock loop frequency multiplier/divider)
MC74F08N (?)
6903 36K (?)
2x P9348 (darlington array for LED control?)
2x P9618 (darlington arary?)

Shuttle HOT-433 v1-3:
UM8881F/9511-BCA (northbridge)
UM8886AF/9512-AYT (southbridge)
UM8663AF/9512-BYS (Super I/O)
UM8667/9511S (supplement to Super I/O -- PS/2 Mouse driver?)
MX8315PC (Phase lock loop frequency multiplier/divider)
6x UM8002/95080 (?)
Y51AH (?)
P49V9 (?)
P9506S8 (Darlington array?)
HD74LS373P (Darlington array?)

hello, i have 486DX4 120mhz with AMI bios

UM8881F
pt-432b motherboard
41-S205-008054-00101111-101094-UMC880-H

can i flash AWARD bios?

UM8667 ...?
From here; http://users.atw.hu/parts/icdb.php it appears listed as;
UM8667 UMC SSOP48 - 2 x RS232
(the chip on motherboard is 48 {2 x 24} pins, which agrees with above line).

UM8002 ...?
Not listed anywhere known, however we can theorize, comparing pictures of
Shuttle HOT-433 V1-to-3, in the specific area to the right of the silkscreened text
for the CPU JP10 jumper - on some boards appears two 74ls244n chips, which are
"buffers and line drivers"... "of three-state memory address drivers, clock drivers,
and bus-oriented receivers and transmitters".
http://www.datasheetcatalog.org/datasheets/320/331414_DS.pdf.
Occupying this exact same area in other examples of Shuttle HOT-433 V1-to-3 is
a UM8002, which apparently is capable of performing the same function.
(Other occurrences of UM8002 appear elsewhere, performing similar functions,
such as {in circuit} between UM8881F Northbridge and the CPU.)
(Interestingly, this posters states;
http://help.wugnet.com/windows2/Mouse-detecte … rderasc-48.html
"If your motherboard is the same as..." [PCCHIPS m506/507],
..."then it uses a UMC UM8663 Super-IO chip which incorporates a floppy
drive controller, two IDE hard drive ports, two COM ports, and a
parallel printer port. I believe the nearby UM8667 (?) chip has the
RS232 drivers for the two COM ports." )

In regard to the discussion about the 8742 Peripheral Interface controller, I haven't
found a large zoomable picture of a Biostar MB8433-UUD v3.1 to enable me to form
a view about that.
Elsewhere though, I did see this statement; http://th2chips.freeservers.com/m507/index.html
"AFAIK the used UMC 8663 Multi I/O has a bug, which prevents the use of the
keyboard AND the mouse at the same time." Although merely their opinion, it got me
wondering - has anyone checked whether all occurrences of the HOT-433 have
UM8663AF , (and 95 year) marking, and do Biostar MB8433-UUD only have
UM8663BF , (and 96 year) marking?
(Other makers motherboards with AF marking, their PS/2 does/doesn't work?
Other makers motherboards with BF marking, their PS/2 does/doesn't work?)
Perhaps AF revision chips had a fault (later corrected in BF~on revisions).

The UM8663 does not control PS/2 functionality. UM8663AF and UM8663BF versions are on boards with working PS/2 mouse ports. UM8886 contains the keyboard controller and PS/2 mouse controller logic.

For the HOT-433, the pins were not wired correctly for PS/2 mouse support. I am not sure which version of the UM8881/8886 chipset added PS/2 mouse support, but the keyboard port is wired to the chipset and I sorta recall one PS/2 line wired to the incorrect pin of the chipset and another pin to the missing keyboard controller chip.

If you are wanting to get PS/2 mice working on the HOT-433, you will most likely need to use the AWARD BIOS version and ensure that the PS/2 mouse option is checked using Modbin.
Then you will need to get a Holtek HT6542B keyboard controller (or AMI KEY 2) and 7406 inverter package. Plug them into the sockets and rewire the motherboard's keyboard controller PS/2 mouse port according to this link,
Native PS/2 mouse implementation for 386/486 boards using the keyboard controller

I am not sure if the keyboard controller will function in just PS/2 mouse mode, or if it needs the keyboard wired to it. You can also try to wire the PS/2 mouse to the UMC chipset in lue of the seperate keyboard controller chip. Look for space on an inverter that is on the MB, or you'll need to add an external inverter. Mouse Data should go to pin 199 on the UM8886BF. Mouse clock should go to pin 200 on UM8886BF. Keyboard data should go to pin 56 of UM8886BF. Keyboard clock should go to pin 57 of UM8886BF.

If my memory is correct, I think I have an early version of the MB-8433UUD with the UM8886AF and a working PS/2 port.