First post, by Bruno128
Hello Vogoners today I present you the build that got me started with this hobby in first place.
So I had a couple of VLB cards lying around in storage since the 90s which were likely removed in upgrade process back in the day. In 2020 I decided to find out what they are good for and set out to build a MS-DOS 486 rig.
Components:
- AMD Am5x86-P75 AMD-X5-133ADW (1996)
- Top Motor clip-on socket 3 cooler (1996)
- QDI V4P895GRN/SMT (1995)
- 256KB UMC UM61256FK-15 cache (1995)
- DTK PTI-265W VLB multi i/o controller (1994)
- 12MB 72-pin FPM (1995)
- Trident 7352 Rev. G2 TGUI9440AGi 1MB VLB (1995)
- Sound Blaster 16 Pro CT2290 (1995)
- Serdaco DreamBlaster S2 (2019)
- 3Com EtherLink III 3C509B-C (1995)
- U.S. Robotics internal Sportster 14.4K (1994)
- Teac CD-540E (2000)
- Sony MF920 3.5” (2003)
- Teac FD-55GFR 5.25” (1993)
- Iomega Zip100 ATAPI (2000)
- Apacer AP-FM25644B IDE DOM 256MB (2004)
- Keyboard lock key (origins unknown)
- Beige tower case with turbo display (1995)
- UTT 235WT AT PSU (1996)
Purpose:
I use it for older adventure games, stuff that needs EMS, etc. For later, more graphically intensive and dynamic titles such as Duke3D I use my newer Pentium II build. Also, based on the old photo I sourced a closest resembling AT tower case so with the actual components installed the whole thing bears some nostalgic value to me.
Performance:
The CPU runs downclocked to 100MHz most of the time.
Notably this system overall is not a speedy one compared to some other 486 chipsets such as SiS 85C471.
Neither configuration reaches the reference benchmark numbers.
Storage:
A 40-pin IDE DOM from some 2004 thin client PC suits my needs just perfectly as fast and silent. Thanks to it I freed up both 3.5” bays for the removable media drives. 256MB of disk space is plenty for DOS and the games of the time. It needs a 5V power supply using a JST micro connector. I can transfer data between any of the following: 3.5” 1.44M disks, 5.25” 360K or 1.2M disks, CDs (-R and -RW as well), ZIP100 disks (GUEST.EXE driver), 10Mb Ethernet (Packet driver), and a modem as a last resort. Mostly I just use the floppies.
TODOs:
By now I consider it mostly finished but I shall replace the PSU capacitors and a noisy PSU fan at some point. A PS/2 to serial from Serdaco is also an interesting thing to add. For now a serial mouse is used.
Tips and interesting stuff:
- Memory testing sound. During the POST this motherboard produces a certain sound through a PC speaker which can be described as ticking or rattling. It doesn’t serve a purpose and can be annoying. Interestingly there is a hidden BIOS option to disable it.
- This multi i/o card uses “other” serial header pinout, the Intel/DTK rather than the popular AT/Everex . Thus any aftermarket breakout header cable likely won't fit. If like me you need a DB25 serial connector with that pinout your best bet is assembling one yourself.
- It appears so that Trident 7352 Rev. G2 can come with both 9440 and 9440AGi chipsets. The card I use is pretty fast and can decently run Duke3D in full screen.
- Socket 3 cooler. While some people just glue the heatsink to the CPU I did not like this approach. So there is a tiny clip-on cooler making a sandwich out of a CPU with a small aluminum heatsink sitting on top of it with a layer of thermal paste. The cooler has plastic tabs which go in the small gap between the CPU and the socket.
- Suspend instead of turbo. I have tried 2 BIOS versions and while the newer v.1.4 allows running Am5x86-P75 faster it loses the turbo switch function and replaces it with suspend even if you check the relevant hidden BIOS option. Because turbo is important, I stayed with an older BIOS version v.1.2 at the cost of some performance. Similar issue was referenced here with no answer.
- This 3Com Ethernet card has a RJ-45 socket and using a packet driver you can surf the WWW with a browser called Arachne. Its other connectivity options are BNC and DA-15 AUI. The latter looks very similar to joystick gameport connector so one needs to be careful when plugging stuff. To initialize the packet driver put the following in autoexec:
LH 3C5X9PD.COM 0x60
- The iomega ZIP100 ATAPI works well in pure DOS using "Guest" driver. I have experienced lockups with its operation until I changed the IDE ribbon cable for a fancier 80-wire one.
- The AMI WINBIOS is way ahead of its time in my opinion. I also want to highlight this important option called “32bit xfer”. If you are using a VLB i/o card rather than an ISA one you should enable it.
- In order to access a number of hidden BIOS options such as write-back cache operation I suggest you try AMISETUP 2.99 by Robert Muchsel.
Photos:
Thanks for reading any questions are welcome and have a nice day!