Specifications
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:
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Bank Number Filled With System Total
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0 64Kx4RAM
1 64Kx4RAM 128Kbytes
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Additional Memory Options:
2or3 64Kx1RAM 192Kbytes
2and3 64Kx1RAM 256Kbytes
2 64Kx1RAM
3 256Kx1RAM 448Kbytes
Alternate 2 or Alternate 3 64Kx4RAM 192Kbytes
Alternate 2 and Alternate 3 64Kx4RAM 256Kbytes
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Banks 2 and 3 and Alternate Banks 2 and 3 require one additional 64Kx1RAM
chip for the parity bit per bank.
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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.