...because we can't all be on the bleeding edge...





486B

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