Green 486

This is a quite cheap 486 from around 1995. It has a very low-quality mainboard like one described HERE, but with working cache, an UN-1082 ISA hard disk controller and Hualon video board. There is also a sound card in ISA slot.
Let's begin with mainboard - its quality is low. It's a FIC mainboard clone, but is unstable with most processors over 66MHz. These boards flooded the market around 1995, when 486 processors in all classes and frequencies started to be affordable and this mainboard has a... 486 compatible made by UMC called "GREEN CPU U5S-SUPER40". Maybe there was an upgrade path in mind, but this mainboard would not pull a DX4 in a stable way. Additionally, VLB is unusable anyway because slots are poor in quality. 16MB of RAM is present in two 8MB sticks. Although there is a "PCChips" sticker on chipset, it's visible that this mainboard has no connection with PCChips - it has much thinner laminate, much worse components and jumpers placed in confusing way. Additionally my unit had some capacitors bulged before most of "capacitor plague" boards became available - even these times there were manufacturers of bad capacitors.
The video board - Hualon or HMC HM86314Q - had a single advantage: It was cheap. Although it looks like a fully 16-bit board, it is not! It is an 8-bit ISA VGA, using 16bit slot expansion for power. Additional lines are not connected or, as can be read here, are led under components and then left disconnected. These boards were sold cheaply until mid-1990s, and they were slow. The only advantage of these boards was that they allowed to work in Super VGA mode. The Multi-IO controller is a Holtek 51265502-V1.5 - a typical I/O controller for 16-bit ISA from these times. The sound card - unidentified Taiwanese 8-bit one, is based on ESS ES488 chip, a SoundBlaster-compatible chip. Works well.
Let's go back to the CPU. What was exactly this UMC SUPER40 processor? In 1990s 486 processors became reproduced by many companies (mostly AMD and Cyrix, but also TI or ST), but all of them had to manufacture somewhere. So it was needed to tape out to the factory. UMC was one of the biggest factories in Taiwan, and if you look at a few mainboards from the first half of 1990s, you will certainly see some chips made by UMC. Around 1993, engineers at UMC designed their own 486SX-compatible CPU, with power management features and advanced microcode optimizations making it run faster than Intel at the same frequency. A year later, Intel sued UMC (and many other companies) for cloning 486. Although most of these fabs were previously doing businesses with Intel or IBM, they got relatively smaller charges but UMC was different, there was no protection money going to Intel so UMC got hit harder - they had to cease selling of their CPUs in USA and most of them were sold to Europe what is described on the chip itself. This CPU got some popularity in Poland. It was even use as a generic 486SX replacement in Adax computers, but later, around 1995, was a base for cheap office-grade computers like this one.

Approx. year 1995

Class AT
Speed 40MHz
RAM 16MB (2x8MB SIMM72)
Mainboard FIC clone? (Similar to this: TH99)
Graphics Hualon HM86314Q
Sound 8-bit ISA ES488
Ports I/O Holtek 51265502-V1.5
Network -
System expansion bus 7x 16-bit ISA slot (3 VLB)
Floppy/removable media drives 1x 3.5" 1.44MB floppy disk drive
CD-ROM drive (2x, ATAPI)
Hard disks/ATA devices: WD Caviar 2340 (TH99)
CHS: 1010/12/55

Peripherals in collection:
 - None

Other boards:


Casing AT Desktop
Non-standard expansions: None
Operating system(s): MS-DOS 6.22 + Windows 3.11 For Workgroups

Contents: Starting, usage Drivers  


The mainboard contains this GUI BIOS made by AMI. Its mouse support is rather scarce, but everything can be operated with keyboard. Chipset settings need to be set properly ad they default to quite low-spec. I found the following configuration works well with SUPER40:
- Advanced setup, cache to write-back (no idea does SUPER40 support WB cache)
- Chipset, turn auto config off, cache waitstates to 2-1-1-1, below it, cache read to 1WS and DRAM WS Select to 1WS. AT Clock PCLK/5 (this is dependent on frontside bus, target about 8MHz).
- DRAM refresh divider to 1/4.
- IO recovery to 5 BCLK.
These settings are highly dependent on used CPU, RAM and bus clock speed, so for other CPU they may be different.

The CD-ROM is a double-speed (2x) Acer CD525E-compatible one (or clone?), made by Lxycon (Model CDM-220) as it can be found on a label, but these drives were released under different brands and are better known as "OTI Scylla" (this text is present only in ATA identification response), it was one of the first affordable drives for a home/office market, even with tray mechanism instead of caddy. Unfortunately its price was low because quality was low. The drive is terribly borked mechanically, the spindle locking mechanism is really poor and head actuator is just made too roughly to operate well (and is loud). The firmware is not totally OK with modern ATAPI. It cannot return ToC in sectored LBA form, and making ISO file in such drive in some conditions makes the file bad. These drives were frequently sold with sound cards, but my unit has different sound card ao probebly was the cheapest thing which could read CDs these times.
Remember that this thing is slow as hell, so make MSCDEX use more memory by passing /M:10 to it. Using original drivers also makes it better. Do not expect it will read all recorded CDs.





Lxycon CD Driver
ES488 sound driver - Drivers for Win3x have been tested
HM86314 driver - Drivers for Win3x have been tested
BIOS v. 19940725