ABIT COMPUTER CORPORATION
VL-BUS 486 MAIN BOARD
Processor | 80486SX/80487SX/80486DX/80486DX2 |
Processor Speed | 25/33/40/50(internal)/50/66(internal)MHz |
Chip Set | UNI |
Max. Onboard DRAM | 32MB |
Cache | 64/128/256KB |
BIOS | AMI/Award |
Dimensions | 330mm x 218mm |
I/O Options | 32-bit VESA local bus slots (2) |
CONNECTIONS | |||
Purpose | Location | Purpose | Location |
Power LED & keylock | CN1 | External battery | CN6 |
Speaker | CN3 | Reset switch | CN8 |
Turbo LED | CN4 | Power LED | LED1 |
Turbo switch | CN5 | 32-bit VESA local bus slots | S1 & S2 |
USER CONFIGURABLE SETTINGS | |||
Function | Jumper | Position | |
» | CMOS memory normal | JP12 | pins 1 & 2 closed |
CMOS memory clear | JP12 | pins 2 & 3 closed | |
» | FAST A20 enabled | JP17 | pins 1 & 2 closed |
FAST A20 disabled | JP17 | pins 2 & 3 closed | |
» | Monitor type select color | JP18 | Closed |
Monitor type select monochrome | JP18 | Open | |
» | Factory configured - do not alter | JP23 | pins 1 & 2 closed |
» | Factory configured - do not alter | JP24 | pins 1 & 2 closed |
» | Factory configured - do not alter | JP25 | pins 1 & 2 closed |
» | Factory configured - do not alter | JP26 | pins 2 & 3 closed |
» | Power good signal detect from power supply | JP27 | pins 2 & 3 closed |
Power good signal detect from board | JP27 | pins 1 & 2 closed | |
» | Factory configured - do not alter | JP28 | pins 2 & 3 closed |
DRAM CONFIGURATION | ||
Size | Bank 0 | Bank 1 |
1MB | (4) 256K x 9 | NONE |
2MB | (4) 256K x 9 | (4) 256K x 9 |
4MB | (4) 1M x 9 | NONE |
8MB | (4) 1M x 9 | (4) 1M x 9 |
16MB | (4) 4M x 9 | NONE |
32MB | (4) 4M x 9 | (4) 4M x 9 |
CACHE CONFIGURATION | ||||
Size | Bank 0 | Bank 1 | TAG write through U15 | TAG write back U14,U15 |
64KB | (4) 8K x 8 | (4) 8K x 8 | 8K x 8 | (2) 8K x 8 |
128KB | (4) 32K x 8 | NONE | 8K x 8 | (2) 8K x 8 |
256KB | (4) 32K x 8 | (4) 32K x 8 | 32K x 8 | (2) 32K x 8 |
CACHE JUMPER CONFIGURATION | |||||||
Size | JP1 | JP2 | JP3 | JP4 | JP5 | JP6 | JP7 |
64KB write through | N/A | N/A | 1 & 2 | 1 & 2 | 2 & 3 | 1 & 2 | 1 & 2 |
64KB write back | 1 & 2 | 1 & 2 | 1 & 2 | 1 & 2 | 2 & 3 | 1 & 2 | 1 & 2 |
128KB write through | N/A | N/A | 2 & 3 | 1 & 2 | 1 & 2 | 1 & 2 | 2 & 3 |
128KB write back | 2 & 3 | 1 & 2 | 2 & 3 | 1 & 2 | 1 & 2 | 1 & 2 | 2 & 3 |
256KB write through | N/A | N/A | 2 & 3 | 2 & 3 | 2 & 3 | 2 & 3 | 2 & 3 |
256KB write back | 2 & 3 | 2 & 3 | 2 & 3 | 2 & 3 | 2 & 3 | 2 & 3 | 2 & 3 |
Note:Pins designated should be in the closed position. |
CPU SPEED CONFIGURATION | |||
Speed | JP20 | JP21 | JP22 |
25MHz | Closed | Open | Closed |
33MHz | Open | Closed | Closed |
40MHz | Closed | Open | Open |
50iMHz | Closed | Open | Closed |
50MHz | Open | Closed | Open |
66iMHz | Open | Closed | Closed |
CPU TYPE CONFIGURATION | ||||
CPU Type | JP13 | JP14 | JP15 | JP16 |
80486SX PGA | open | pins 2 & 3 closed | Open | Closed |
80486 SX PQFP | open | pins 2 & 3 closed | Open | Open |
80487SX | pins 2 & 3 closed | pins 1 & 2 closed | Closed | N/A |
80486DX, DX2 | pins 1 & 2 closed | pins 1 & 2 closed | Closed | N/A |
VESA WAIT STATE/BUS SPEED CONFIGURATION | |||||
CPU speed | Wait states | JP8 | JP9 | JP10 | JP11 |
< 33MHz | 0 wait states | pins 1 & 2 | pins 1 & 2 | pins 1 & 2 | pins 1 & 2 |
> 33MHz | 1 wait state | pins 2 & 3 | pins 2 & 3 | pins 2 & 3 | pins 2 & 3 |
Note: Pins designated should be in the closed position. |