All my content and ptohos
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 | |
| CPU | UMC Green CPU U5S-SUPER40 | |
| Speed | 40MHz | |
| RAM | 16MB (2x8MB SIMM72) | |
| ROM | AMI BIOS | |
| 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 |
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Peripherals in collection: |
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| Other boards:
|
None | |
| Casing | AT Desktop | |
| Non-standard expansions: | None | |
| Operating system(s): | MS-DOS 6.22 + Windows 3.11 For Workgroups |
| Contents: | Starting, usage | Drivers |
Starting
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.
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Lxycon CD Driver |
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ES488 sound driver - Drivers for Win3x have been tested |
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HM86314 driver - Drivers for Win3x have been tested |
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BIOS v. 19940725 |