HwMuseum | Index

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