Compaq Portable 286 Compaq Portable Computer, Compaq Plus Personal Computer, a - Page 119

K x 1 RAM

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Bank 3 also consists of eight sockets that can be populated either with 64K x 1 RAM chips or 256K x 1 RAM chips. In addition to Banks 2 and 3, Version 2 also contains Alternate Bank 2 and Alternate Bank 3. Sockets in both Alternate Bank 2 and 3 can each be populated with two 64K x 4 RAM chips. Bank 2 and Alternate Bank 2 use a common chip for the parity bit (U37). Bank 3 and Alternate Bank 3 also use a common chip for the parity bit (U36). If Banks 2 and 3 are used, Alternate Banks 2 and 3 are not used. If Alternate Banks 2 and 3 are used, Banks 2 and 3 are not used. Version 2 contains a shunt jumper that is used for selecting either Banks 2 and 3 or Alternate Banks 2 and 3. The banks are selected as follows: To enable Banks 2 and 3, insert the shunt jumper so that pins 5-12, 6-11, 7-10, and 8-9 are connected. To enable Alternate Banks 2 and 3, insert the shunt jumper so that pins 1-16, 2-15, 3-14, and 4-13 are connected. The banks are selected by removing the shunt jumper, rotating it 180 degrees and reinserting it. The shunt jumper must be installed for the system board to operate. The following chart shows the possible memory configuration on the board: Bank Number Filled With System Total 0 64K x 4 RAM 1 64K x 4 RAM 128 Kbytes Additional Memory Options: 2 or 3 64K x 1 RAM 192 Kbytes 2 and 3 64K x 1 RAM 256 Kbytes 2 64K x 1 RAM 3 256K x 1 RAM 448 Kbytes Alternate 2 or Alternate 3 64K x 4 RAM 192 Kbytes Alternate 2 and Alternate 3 64K x 4 RAM 256 Kbytes Banks 2 and 3 and Alternate Banks 2 and 3 require one additional 64K x 1 RAM chip for the parity bit per bank. Because all version 2 boards contain Revision C or higher ROMs, only one switch, SW1, is installed. Switch SW2 is not installed. See Table 8.7-1 above.

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Bank 3 also consists of eight sockets that can be populated either with
64K x 1 RAM chips or 256K x 1 RAM chips.
In addition to Banks 2 and 3, Version 2 also contains Alternate Bank 2 and
Alternate Bank 3. Sockets in both Alternate Bank 2 and 3 can each be
populated with two 64K x 4 RAM chips. Bank 2 and Alternate Bank 2 use a
common chip for the parity bit (U37). Bank 3 and Alternate Bank 3 also use a
common chip for the parity bit (U36).
If Banks 2 and 3 are used, Alternate Banks 2 and 3 are not used. If Alternate
Banks 2 and 3 are used, Banks 2 and 3 are not used.
Version 2 contains a shunt jumper that is used for selecting either Banks 2
and 3 or Alternate Banks 2 and 3. The banks are selected as follows:
To enable Banks 2 and 3, insert the shunt jumper so that pins 5-12, 6-11,
7-10, and 8-9 are connected.
To enable Alternate Banks 2 and 3, insert the shunt jumper so that pins 1-16,
2-15, 3-14, and 4-13 are connected.
The banks are selected by removing the shunt jumper, rotating it 180 degrees
and reinserting it. The shunt jumper must be installed for the system board
to operate.
The following chart shows the possible memory configuration on the board:
==============================================================================
Bank Number
Filled With
System Total
------------------------------------------------------------------------------
0
64K x 4 RAM
1
64K x 4 RAM
128 Kbytes
------------------------------------------------------------------------------
Additional Memory Options:
2 or 3
64K x 1 RAM
192 Kbytes
2 and 3
64K x 1 RAM
256 Kbytes
2
64K x 1 RAM
3
256K x 1 RAM
448 Kbytes
Alternate 2 or Alternate 3
64K x 4 RAM
192 Kbytes
Alternate 2 and Alternate 3
64K x 4 RAM
256 Kbytes
------------------------------------------------------------------------------
Banks 2 and 3 and Alternate Banks 2 and 3 require one additional 64K x 1 RAM
chip for the parity bit per bank.
==============================================================================
Because all version 2 boards contain Revision C or higher ROMs, only one
switch, SW1, is installed.
Switch SW2 is not installed. See Table 8.7-1 above.