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PB800/PB900 LAYOUT

NOTE:


There are two revisions of the PB800/900 motherboard.

1. LAYOUT


A. Revision C

NOTE:


Holds 1MB of RAM (256 x 1 chips), arranged in four rows of nine chips per row (8 bits of ram and 1 parity bit.) The CMOS backup battery is a removable AT style battery.


B. Revision D


NOTE:

Holds 1MB of RAM (256K x 4 chips) arranged in 2 rows of 4 and parity 1 row of 4 (256K x 1 chips) upgradeable to 2MB with same chips plugged in adjacent sockets. CMOS Battery is soldered


2. SOCKETS


NOTE:

1. If chip at U14 is P82C212, BIOS must be 3.10.08a or 3.10.12 If chip at U14 is P82C212B, Bios must be 3.10.14

2. REV-D motherboard holds 2MB of RAM. Each Megabyte is (8) 256k x 4 and (4) 256k x 1 chips for parity.

Socket

Chip

Description
U7 8042 Keyboard Controller
U10 83C206  
U14 82C212 or 82C212B  
U15 80286 Main Processor
U16 80287 Math Coprocessor (optional)
U17 30-32MHZ Crystal (optional)
U47   BIOS (High)
U69
BIOS (Low)
U48 82C215  
U49 82C211C  

3. JUMPERS


NOTE

If a 80287-10 is installed you must also add a 30-32MHz crystal at U17 in addition to setting the jumper.


4. CONNECTORS



5. RISER CARD


NOTE: This system does not use a riser card.

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