Tulip Vision Line DT 5/166

This is a fairly compact desktop-configuration system I bought in December 2022 from a seller on Ebay that deals in vintage PC equipment.

The case was pretty dirty when it arrived, but a little bit of soap and water and a magic eraser and it came up looking lovely:

Motherboard is a compact design with a shared ISA/PCI riser, and is based on the very common Intel Triton II chipset (i430VX) with lot of integrated peripherals (dual channel PCI IDE controller, Alliance ProMotion PCI VGA, AMD PCNet 10mbit ethernet):

Apparently there are multiple revisions of this motherboard with some having dual-voltage processor support, some having S3 VGA and optional sound support. Mine unfortunately is an early model without any of those options.

• Desktop Chassis
• Processor: None (was originally Intel Pentium 166 - P54CS)
• Motherboard: Tulip DT48 (Intel Triton II - 430VX), 256KB cache, AMD PCNet 10mbit ethernet, PS/2 Mouse, PS/2 Keyboard
• RAM: None (would originally have had 16-64MB)
• Video: PCI Alliance ProMotion AT24 (1MB, integrated into motherboard)
• ATX PSU

• Processor: Intel Pentium 166
• RAM: 2x 32MB EDO SIMMs
• Video: Diamond Stealth 64 DRAM (2MB S3 Trio64) + Diamond Monster 3D (4MB Voodoo 1)
• Audio: ESS Audiodrive 1868F + NEC/Yamaha DB60XG
• Storage: 3.5“ Floppy Drive, Front bay mounted CF reader on primary IDE channel (Kingston Ultimate 266x 16GB)

Other than the missing processor and missing RAM, this was in pretty good condition and powered on as soon as I put the missing parts in from my spares.

One minor problem I encountered was the noise of the original ATX PSU fan. That was easily solved by replacing it with a pair of quiet push-pull Noctua fans which dropped the noise significantly.

The main problem when trying to use the system was that I could not find a single floppy drive from my set of half a dozen or so drives that would work. An interesting observation was that the floppy cable included with the system (which looked original) only had a single drive connector and no twist. Normally the twist is there to allow the drive at the end of the cable to be recognised as A:, with the drive behind the twist as B:. The reasons for this are historical, but basically IBM decided it would be easier if all the floppy drives they produced where jumpered identically, the twist flipping the drive ID's in the wiring.

Unfortunately nothing I tried worked - I could get drives to be detected as B:, regardless of what I set the onboard drive jumpers to say, but none would work as A:. In addition, several of the drives that got detected as B: through read errors when trying to access them from within a booted DOS session.

In the end I worked out that the Tulip motherboard must perform the 'twist' onboard, and not in the cable and that compatible drives must be jumpered to disable the drive Disk Change signal. That is to say, if your drive has it enabled by default (and most of my modern 3.5” floppy drives did), then disable it. It seems that Tulip did this across a number of their models in order that faulty drives could not be exchanged with off-the-shelf parts and their service/support department were needed instead (how many schools/offices are going to have someone to desolder a drive ID jumper and a disk change enable jumper from the floppy control PCB?).

Anyway, if you come across a Tulip PC in the wild, and need to replace the floppy drive, then it's a good possibility that you will need to jumper the drive as ID1 (or ID0, depending on whether the drive is numbered 0-3 or 1-4) rather than the IBM standard of ID 2 (or 1, if your drive starts from 0) AND you need to disable the disk change signal.

Unfortunately I've not been able to find a single reference manual for the Vision Line DT5/166. If you do find one, then be careful that there were several variations of the motherboard; at least 'early' and 'late' designs where early boards (such as mine) do not have the split-voltage support needed for Pentium MMX (or Cyrix 6x86L) processors, so you are stuck to non-MMX models (effectively a Pentium 200 being the best cpu you can fit).

The Intel 430VX chipset is the 'poor cousin' of the 430HX and 430TX, but it still delivers solid performance. Non-accelerated Quake playback in low res is very acceptable and of course titles from the previous generation (i.e. DOOM) are as smooth as you could ever expect them to be. At the time these systems came out I was an owner of a Cyrix 6×86 P166+ - having seen the real Pentium 166 perform in Quake, I can see now why it caused the downfall of Cyrix!

It's interesting to compare this system with the Digipos Pro, which is from approximately the same era, has the same CPU socket (socket 7) and takes the same generation of processors. The Digipos system has much better RAM throughput from it's Ali Aladdin chipset (with the same type of memory - 2x 32MB EDO), but the much lower clocked Pentium 166 of the Tulip is significantly faster than the Winchip 200 of the Digipos. The Intel chipset/PCI IDE controller is also far, far faster than the (almost ISA speed) IDE of the Digipos, leading to a much more responsive system. It will be interesting to see whether an Intel processor in the Digipos system can improve things.