486B Motherboard Settings and Configuration
ISA/EISA, INC.
486B
Processor | 80486SX/80487SX/80486DX |
Processor Speed | 20/33MHz |
Chip Set | OPTI |
Max. Onboard DRAM | 32MB |
SRAM Cache | 64/256KB |
BIOS | AMI |
Dimensions | 330mm x 218mm |
I/O Options | None |
NPU Options | 4167 |
CONNECTIONS | |||
Purpose | Location | Purpose | Location |
Power LED & keylock | J1 | Turbo switch | JP2 |
Speaker | J3 | Turbo LED | JP21 |
External battery | J4 | Cooling fan switch | JP25 |
Reset switch | JP1 | Cooling fan power | USP8 |
USER CONFIGURABLE SETTINGS | |||
Function | Jumper | Position | |
| » | Factory configured - do not alter | JP10 | unknown |
| » | CPU speed select switchable at keyboard | JP12 | pins 1 & 2 closed |
CPU speed select switchable at turbo switch | JP12 | pins 2 & 3 closed | |
| » | Factory configured - do not alter | JP26 | open |
| » | Video BIOS shadow before initialization | JP27 | pins 1 & 2 closed |
Video BIOS shadow after initialization | JP27 | pins 2 & 3 closed | |
CPU JUMPER CONFIGURATION | |||
CPU | JP22 | JP23 | JP24 |
80486DX (33MHz) | pins 1 & 2 closed | pins 1 & 2 closed | pins 1 & 2 and 3 & 4 closed |
80487SX (20MHz) | pins 3 & 4 closed | pins 2 & 3 closed | pins 1 & 2 and 3 & 4 closed |
80486SX (20MHz) | pins 2 & 3 closed | pins 2 & 3 closed | 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 |
5MB | (4) 1M x 9 | (4) 256K x 9 |
8MB | (4) 1M x 9 | (4) 1M x 9 |
16MB | (4) 4M x 9 | NONE |
17MB | (4) 4M x 9 | (4) 256K x 9 |
20MB | (4) 1M x 9 | (4) 4M x 9 |
20MB | (4) 4M x 9 | (4) 1M x 9 |
32MB | (4) 4M x 9 | (4) 4M x 9 |
SRAM JUMPER CONFIGURATION | |||||
Size | JP6 | JP7 | JP8 | JP9 | JP20 |
64KB | pins 1 & 2 | pins 1 & 2 | pins 1 & 2 | pins 1 & 2 | pins 1 & 2 |
256KB | pins 2 & 3 | pins 2 & 3 | pins 2 & 3 | pins 2 & 3 | pins 1 & 2 |
Disabled | N/A | N/A | N/A | N/A | pins 2 & 3 |
Note:Pins designated should be in the closed position. | |||||
SRAM CONFIGURATION | ||
Size | Cache SRAM | TAG |
64KB | (8) 8K x 8 | (1) 8K x 8 |
256KB | (8) 32K x 8 | (1) 32K x 8 |
I/O BUS SPEED JUMPER CONFIGURATION | ||||||
Bus Speed | JP3 | JP4 | JP5 | JP13 | JP14 | JP15 |
CPU/8 | open | open | open | open | open | closed |
CPU/6 | open | open | open | open | closed | open |
CPU/5 | open | open | open | closed | open | open |
CPU/4 | open | open | closed | open | open | open |
CPU/3 | open | closed | open | open | open | open |
CPU/2 | closed | open | open | open | open | open |
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