I can finally post an update about this 486 VLB system. It was in limbo for a long time. But I recently decided to just finish things in a quick way. Especially the interfacing at the front of the case, so I can put the cover on the case. I cheated using quick tie-rib fixtures.
What changed since 2016: Different memory modules. Different VLB Video card. Different SD Card. Fixed the BIOS regarding >2GB HDD-size display (attached).
486 VLB - Current Config
- Motherboard: Original TK8498F VLB Motherboard, with UMC 498F Chipset + 256kB Cache. Added heat-sink to VRM. Replaced battery.
- PSU: Original one, Replaced Fan and connected it to just 5V.
- Case: Original one.
- BIOS: Award 1995 2.21r BIOS with >2GB HDD-size display fix. Stored in new 64kB EEPROM, with 5V jumper mod.
- CPU: Cyrix 5x86-100MHz (adjustable to 33MHz and 66MHz as well, with mechanical switch and/or SetMul)
- Memory: 2x16MB FPM 60ns.
- Multi-I/O: Boca Research IDEVL2M with Atronics 2015PL chipset. A VLB Multi-I/O without separate BIOS.
- Video card: Diamond Stealth 64 DRAM VLB. S3 Vision864 chipset. 2MB.
- Monitor: TFT DELL E151FP (2002), D-Sub input only. 1024x768 native, auto-upscale.
- Sound: Acer Magic S23, CS4232 + OPL3. Using IRQ 7. Combined with a Korg 4MB Midi daughter board.
- Storage: 8GB SD Card PNY (C10/U1) on KTC FC1306T adapter, on 90-degree angle bracket. With SD extension cable.
- Mouse: PS/2 optical mouse from Logitech, Type M-SBF96. With Matze79's PS/2 to serial mouse adapter. Using COM 1.
- Keyboard: Samsung SEM-K 20S with DIN connector.
- OS: Windows 95 OSR2 with MS-DOS 7.
(Currently no floppy disk or CD drive. Disabled the COM 2 port and the parallel port)
I have a Goldstar Prime 2C ISA Multi-I/O card that, according two to benchmarks, performs a bit better in DOS: 1566 kB/s compared to a depressing 1323 kB/s for the above VLB card. On the other hand, the VLB card does much better in Windows 95 with its driver.
In practice with the VLB card in DOS; loading up Doom 2 to menu screen takes 15 seconds. With smartdrv 14 seconds. I suppose the SD card's access time is helping out here.
The VLB Multi-I/O card FAQ says, that one is not supposed to use its DOS sys driver when LBA scheme is enabled. LBA is essential for interfacing the 8GB Drive.
Another thought is that the AMI BIOS "IDE 32-Bit Mode" toggle is surely not available, nor working with the Award BIOS that I am using. And I just found that exact concern mirrored in this recent topic pages 6 and 7.
EDIT: First I found that the BIOS-setting "Local Ready Delay Setting" should be put on "No Delay". Basically all BIOS delays and wait-states are now at the absolute minimum. This improves disk access a little. Next I messed around with the DOS VLB IDE driver: This card also has an updated DOS driver which is told to work with LBA enabled, contrary to the older one. But whatever the settings it makes disk access slower! At best it resulted in around 1000 kB/s. What I found though, is that the driver does enable something good on the IDE card, which remains active even after a warm reboot. So now I made this SPEED.bat file that loads the 2015PL.sys device driver using CTLOAD.com, then warm-reboots using REBOOT.com. This way I get 1725 kB/s IDE speed, without any driver loaded. It does take a warm reboot to get there (A warm reboot being like Ctrl-Alt-Del, but not like the case Reset button). That 1725 is a big improvement over 1323.
Last modification, before finally closing the case-cover: Lacking case airflow, the heat of the CPU and VRM was just being trapped. I don't like these old parts heating up, so I added a small 12V fan, on an improvised bracket. Also added small Gelid-branded fan-controller. 7V is seemingly sufficient to reliably start the fan, whilst decreasing the rpm to make it silent.
Some benchmarks comparable with the table on page 2 of this topic, now with S3 Vision864 graphics:
3D Bench = 83,3
3D Bench 1.0c = 81,1
PCP Bench VGA Mode = 17,5
PCP Bench 640x400, using UniVBE 5.0 = 7,5
Doom v1.9 Demo3 + SFX = 3863 / 3041 * 35 = 44,46 frames/sec
SpeedSys v4.78 = 52,23
Duke Nukem 3D, 320x200, SFX+Midi, Full HUD, initial view E1M1 = 29 frames/sec
Just noticed that this video card has tantalum capacitors. Not sure I trust that for the coming years. It seems to be standard issue for such a card.