VOGONS


First post, by jasa1063

User metadata
Rank Member
Rank
Member

I recently got a 386/40 computer with a Biostar motherboard containing a MACRONIX MX83C305FC/MX83C306FC chipset. I am using Micro-Labs ET4000AX video card, Sound Blaster 16 CT4170 sound card, and a GoldStar Prime 2c multi IO card. I have Compact Flash to IDE adapter with a 2GB Compact Flash card running DOS 6.22. The AMI BIOS has options to change the divider for the AT Bus clock from 2-5. Here are the results of a few benchmarks:

AT bus clock divider 5 (8Mhz)
3Dbench 1.0 - 14.4 FPS
Coretest 3.03 - 2.2 MBs

AT bus clock divider 4 (10Mhz)
3Dbench 1.0 - 15.6 FPS
Coretest 3.03 - 2.4 MBs

AT bus clock divider 3 (13.3Mhz)
3Dbench 1.0 - 15.6 FPS
Coretest 3.03 - 2.9 MBs

AT bus clock divider 2 (20Mhz)
3Dbench 1.0 - 16.0 FPS
Coretest 3.03 - 3.3 MBs

At 20Mhz my Sound Blaster 16 does not work at all, so the highest stable clock I can get is at 13.3Mhz. As you can see there is a point of diminishing returns with the video card beyond 10Mhz. The disk performance does continue to scale up. I decided to run the AT bus at 10Mhz as I feel that is a pretty safe overclock to run for an extended period of time. I am curious what others have experienced overclocking the AT bus on their 386 or 486 system.

Reply 1 of 22, by maxtherabbit

User metadata
Rank Oldbie
Rank
Oldbie

10MHz works stably on just about every machine and card set I've tried it with. It's a very conservative OC. I would not be afraid to run 13MHz for an extended duration if it is stable for you.

Reply 2 of 22, by jasa1063

User metadata
Rank Member
Rank
Member
maxtherabbit wrote on 2020-11-29, 16:09:

10MHz works stably on just about every machine and card set I've tried it with. It's a very conservative OC. I would not be afraid to run 13MHz for an extended duration if it is stable for you.

I appreciate the feedback. I will give the 13.3Mhz a try for awhile and see how it goes. Thanks!

Reply 3 of 22, by jasa1063

User metadata
Rank Member
Rank
Member
jasa1063 wrote on 2020-11-29, 16:19:
maxtherabbit wrote on 2020-11-29, 16:09:

10MHz works stably on just about every machine and card set I've tried it with. It's a very conservative OC. I would not be afraid to run 13MHz for an extended duration if it is stable for you.

I appreciate the feedback. I will give the 13.3Mhz a try for awhile and see how it goes. Thanks!

After running at 13.3Mhz for a few hours I had stability problems with my Compact Flash drive. I am going to just keep it at 10Mhz

Reply 4 of 22, by konc

User metadata
Rank Oldbie
Rank
Oldbie
jasa1063 wrote on 2020-11-29, 23:22:

After running at 13.3Mhz for a few hours I had stability problems with my Compact Flash drive. I am going to just keep it at 10Mhz

Yes matches my experience too. I narrowed it down the the controller though, some were able to cope with a divider of 3 with the same CF card but most couldn't.

Reply 5 of 22, by The Serpent Rider

User metadata
Rank l33t
Rank
l33t

As you can see there is a point of diminishing returns

Try Doom and there won't be any diminishing returns.

At 20Mhz my Sound Blaster 16 does not work at all

Some late sound cards like ALS100 will work fine.

Get up, come on get down with the sickness
Open up your hate, and let it flow into me

Reply 6 of 22, by jasa1063

User metadata
Rank Member
Rank
Member

I made a few changes to get things running at 20Mhz with a AT bus divider of 2. I swapped out the GoldStar Prime 2C Multi IO card I was using and for one that has a UMC chipset. I have had no more issues with my Compact Flash card. I added the /CS parameter to UNISOUND to treat the CT4170 SB16 card as a non Plug-n-Play card and it initializes and works just fine.

Reply 7 of 22, by Anonymous Coward

User metadata
Rank l33t
Rank
l33t

That's interesting about the Goldstar Prime 2 card. I wonder if they're all more or less constrained to 10MHz. If the UMC can handle 20MHz that's good to know. Which UMC chip is on there?

I wonder how the Winbonds fare.

"Will the highways on the internets become more few?" -Gee Dubya
V'Ger XT|Upgraded AT|Ultimate 386|Super VL/EISA 486|SMP VL/EISA Pentium

Reply 8 of 22, by jasa1063

User metadata
Rank Member
Rank
Member
Anonymous Coward wrote on 2020-12-05, 16:51:

That's interesting about the Goldstar Prime 2 card. I wonder if they're all more or less constrained to 10MHz. If the UMC can handle 20MHz that's good to know. Which UMC chip is on there?

I wonder how the Winbonds fare.

Here is a picture of the Multi IO card I am using.

Attachments

  • IMG_0778a.jpg
    Filename
    IMG_0778a.jpg
    File size
    399.38 KiB
    Views
    452 views
    File comment
    Multi IO Card
    File license
    Public domain

Reply 10 of 22, by jasa1063

User metadata
Rank Member
Rank
Member
douglar wrote on 2020-12-06, 02:12:
jasa1063 wrote on 2020-12-06, 01:58:

Here is a picture of the Multi IO card I am using.

Does the IDE interface go faster when you over clock the bus?

Yes, see my first post in this thread. The results from Coretest 3.03 are for IDE disk transfer rates.

Reply 11 of 22, by Anonymous Coward

User metadata
Rank l33t
Rank
l33t

Thanks. I'll keep my eyes open for cards with those chips. Maybe they're the same ones used on the VLB version?

"Will the highways on the internets become more few?" -Gee Dubya
V'Ger XT|Upgraded AT|Ultimate 386|Super VL/EISA 486|SMP VL/EISA Pentium

Reply 12 of 22, by jasa1063

User metadata
Rank Member
Rank
Member
Anonymous Coward wrote on 2020-12-06, 02:44:

Thanks. I'll keep my eyes open for cards with those chips. Maybe they're the same ones used on the VLB version?

The answer is yes to a VLB version (although these links are currently out of stock):

https://www.ebay.com/itm/ISA-I-O-card-UMC-UM8 … G-/184416599325
https://www.amazon.com/UMC-UM82C865F-Multi-I- … uct_top?ie=UTF8

That would explain the ability to run at the 20Mhz bus speed, since VLB cards run at 33Mhz-40Mhz.

Reply 13 of 22, by douglar

User metadata
Rank Member
Rank
Member
jasa1063 wrote on 2020-12-06, 02:28:
douglar wrote on 2020-12-06, 02:12:

Does the IDE interface go faster when you over clock the bus?

Yes, see my first post in this thread. The results from Coretest 3.03 are for IDE disk transfer rates.

I see that the IDE transfers are faster. Love it.

I wasn't clear enough when I asked my question. I was wondering if you increased the ATA signaling speed over the IDE cable when you raising the AT bus speed or if the crystal on the card keeps the ATA speed constant and all of the performance gains came from the faster AT bus.

Reply 14 of 22, by jasa1063

User metadata
Rank Member
Rank
Member
douglar wrote on 2020-12-22, 17:04:
jasa1063 wrote on 2020-12-06, 02:28:
douglar wrote on 2020-12-06, 02:12:

Does the IDE interface go faster when you over clock the bus?

Yes, see my first post in this thread. The results from Coretest 3.03 are for IDE disk transfer rates.

I see that the IDE transfers are faster. Love it.

I wasn't clear enough when I asked my question. I was wondering if you increased the ATA signaling speed over the IDE cable when you raising the AT bus speed or if the crystal on the card keeps the ATA speed constant and all of the performance gains came from the faster AT bus.

I did not increase ATA signaling speed. All the performance gains are from the faster AT Bus.

Reply 15 of 22, by pshipkov

User metadata
Rank Member
Rank
Member

I had good experience with GoldStar Prime 2 IDE controllers, CF cards and overclocking 386 hardware.
On some better 386 boards they can handle 3.6+ Mb/s @ 25MHz AT bus, no problem.
Didn't notice much difference between them and UMC ones.
Maybe the one you got is tired from the many years of service. 😀

Reply 16 of 22, by mkarcher

User metadata
Rank Member
Rank
Member
jasa1063 wrote on 2020-12-31, 01:02:
douglar wrote on 2020-12-22, 17:04:

I wasn't clear enough when I asked my question. I was wondering if you increased the ATA signaling speed over the IDE cable when you raising the AT bus speed or if the crystal on the card keeps the ATA speed constant and all of the performance gains came from the faster AT bus.

I did not increase ATA signaling speed. All the performance gains are from the faster AT Bus.

You did increase the ATA signalling speed. You did not increase the ATA signalling speed explicitly, though. An ISA IDE interface card (it's more correct to not call it a controller, as it does not control anything itself) just passes the ISA signals to the ATA cable. If the ISA bus runs at a higher clock rate, the signalling speed on the ISA bus is increased, and thus the signalling speed on the IDE cable is increased, too.

Reply 17 of 22, by frudi

User metadata
Rank Member
Rank
Member
jasa1063 wrote on 2020-12-06, 01:58:
Anonymous Coward wrote on 2020-12-05, 16:51:

That's interesting about the Goldstar Prime 2 card. I wonder if they're all more or less constrained to 10MHz. If the UMC can handle 20MHz that's good to know. Which UMC chip is on there?

I wonder how the Winbonds fare.

Here is a picture of the Multi IO card I am using.

I'm using a similar IO card in my 386DX-40, same UMC chips, similar board dimensions, just slightly different layout. So this thread got me curios to try and play with the ISA bus clock. 10 MHz worked fine, 13.3 MHz caused lock-ups in some benchmarks, yet so far 16 MHz (my board has a setting for it) seems to be working without issues; haven't tried 20 MHz yet.

In benchmarks, the difference going from 8 to 16 MHz was:
3D Bench 1.0: 15.3 -> 16.9
PC Player Bench: 3.9 -> 4.1 fps (was 4.0 at 10 MHz and 4.1 at 13.3 MHz, so this test doesn't seem to scale well)
TOPBENCH: 83 -> 98
Doom (lowest quality): 28.5 -> 30.3 fps
Quake 320x200: no measurable difference, 1.6 fps in both cases
NU System Info Disk benchmark: 2.2 -> 3.1 MB/s

I even saw about a 1% increase in speedsys memory throughput (20.6 -> 20.8 MB/s), not much but it was consistent and repeatable.

Seems like a decent boost for very little work 😀

Reply 18 of 22, by jasa1063

User metadata
Rank Member
Rank
Member
mkarcher wrote on 2020-12-31, 10:46:
jasa1063 wrote on 2020-12-31, 01:02:
douglar wrote on 2020-12-22, 17:04:

I wasn't clear enough when I asked my question. I was wondering if you increased the ATA signaling speed over the IDE cable when you raising the AT bus speed or if the crystal on the card keeps the ATA speed constant and all of the performance gains came from the faster AT bus.

I did not increase ATA signaling speed. All the performance gains are from the faster AT Bus.

You did increase the ATA signalling speed. You did not increase the ATA signalling speed explicitly, though. An ISA IDE interface card (it's more correct to not call it a controller, as it does not control anything itself) just passes the ISA signals to the ATA cable. If the ISA bus runs at a higher clock rate, the signalling speed on the ISA bus is increased, and thus the signalling speed on the IDE cable is increased, too.

Thanks for the clarification.

Reply 19 of 22, by Anonymous Coward

User metadata
Rank l33t
Rank
l33t

You should try your tests again with a DLC-40. If the bottleneck is the CPU, then you might get better gains from overclocking ISA with the DLC.

"Will the highways on the internets become more few?" -Gee Dubya
V'Ger XT|Upgraded AT|Ultimate 386|Super VL/EISA 486|SMP VL/EISA Pentium