"Joy" 5x86 PC

This PC has one of the fastest 486 processors ever made - AMD 5x86-P75 133MHz processor - a 486 which was running internally at 133MHz, being comparable with Pentium 75's performance. It has 32MB of RAM, 1.3GB hard disk and fast VLB Cirrus Logic video card with built-in 32bit ATA controller. Additionally it has 10x CD-ROM drive. These computers were used near 1996/7 as highly upgraded 486 for multimedia and design applications. Most demanding programs work well with Windows 95 there and it doesn't swap too much even with few programs running simultaneously.

The machine has been assembled first as some 486 by "Joy Computer", a computer company in Cracow, Poland who was importing computer parts and assembled ready computers for different applications.

Approx. year 1996

Class AT
CPU AMD 5x86-P75
Speed 133MHz
RAM 32MB (2x16MB, SIMM30-pin)
ROM Award BIOS 4.50
Mainboard Abit AH4T Rev. 1.2 (TH99)
Graphics Cirrus Logic CL-9026 (GD5426 chip), (VLB), with PATA controller. 2MB VRAM
Sound AdvanceLogic / Realtek / ALR ALS007 (16-bit ISA)
Ports I/O DTK PTI227W V3 (16-bit ISA) (TH99)
Network 3Com EtherLink III 3C509 (16-bit ISA)
System expansion bus 8-bit ISA x1
16-bit ISA x4
VLB x3
Floppy/removable media drives 1x 3.5" 1.44MB floppy disk drive
Hard disks/ATA devices: Seagate Medalist ST31720A PATA (C/H/S: 3305/16/63, LBA)

Aztech 10x CD-ROM drive.

Peripherals in collection:
 - None

Other boards:


Casing Standard small AT tower
Non-standard expansions: None
Operating system(s): Windows 95

Contents: Starting, usage Drivers  


Mainboard starts normally, but the setup defaults to lowest possible settings - for most 72-pin SIMMs memory can be switched to faster modes in chipset setup. It is important that when using VLB video board to set VLB signals to "Synchronize" instead of "Transparent". If not, you will have problems with display even in text mode if VLB board is used.
This mainboard can work using single SIMM.

This mainboard is generally unstable on 64MB of RAM and higher. I was trying to test 64MB with it and it was hanging when running Windows 95.

AMD 5x86 is a 486 running with 33MHz bus at 4x multiplier. With most mainboards CPU is set to 33MHz x2, because the CPU doubles frequency inside. When installing 5x86 one should take care of voltage as 5x86 works on 3.45V, not 5V like typical DX and DX2s, so mainboard has to be configured using proper voltage selection. If it is not possible, there are special voltage regulator converters to fit between socket and CPU. Nevertheless, this CPU needs both fan and heatsink - large heatsing is NOT sufficient.

Many 486 mainboards don't detect this CPU as 133MHz as they have no information about it in BIOS. My Abit AH4T mainboard detected it as AMD 486DX4-S 120MHz, while it is indeed running on 133MHz.

Video board jumper settings:

| :::::::PATA:::::::     ::VESA::
|              ... JP1
|:             ... JP2
|:<-ATA LED    ... JP3
|              ... JP4 
|          PIN1        JP5 ...
|                      JP6 ... 
|   _         __       PIN1
-||| |||||||||  |||||||||| ||||||

JP1 - 1-2 - IDE enabled; 2-3 - IDE disabled
JP2 - Bus speed: 1-2 - 33MHz; 2-3 - 50MHz
JP3, JP4 - IDE transfer mode (in order):
 2-3, 2-3 - Mode 0
 2-3, 1-2 - Mode 1
 1-2, 2-3 - Mode 2
 1-2, 1-2 - Mode 3
JP5 - IRQ9 - 1-2 - Enable; 2-3 - Disable
JP6 - IOCHRDY Signal 1-2 - Enable; 2-3 - Disable.





ALS007 sound board (DOS/Win95)
3Com 3C509 configuration bootdisk -  it boots DOS and configuration tool for ISA boards.
Abit AH4T mainboard manual
Abit AH4T BIOS v. 4.50G
3Com 3C509 boot-ROM BIOS - not tested.