96K PRAM BOARD, 562411
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The 96K PRAM board was designed primarily to increase the 2120 memory capacity and decrease the number
of BMUX slots required for memory boards. Each bank of memory is still 32K, but there are now three 32K banks
on each 96K PRAM board.
In terms of
32K PRAM boards,
ONE 96K PRAM Board
= THREE 32K PRAM Boards
As shown in the illustration above, the three banks on each 96K PRAM board are referred to as bank A, bank
8, and bank C.
The upper bank, also called the common bank, hotds the system’s main (executive) operating program. In all
2120 systems using 96K PRAM boards, bank A on the first PRAM board is designated as common.
The 96K PRAM board has five switch packages. Switch packages Sl and S2 are used to select system common
memory and “standard” banks. Switch packages S3, S4, and S5 are used to set each bank’s address range.
Although the 96K PRAM board contains both PROMS and RAMS, its design eliminates the need to identify
whether a slot contains a PROM or RAM chip.
Before setting the switches, let’s look at a PROM label. The first line of information on the label is the program
number. The second line tells what card this is and what IC socket this PROM goes into. The third line is the date
the chip was programmed. For example,
PROGRAM NUMBER
PRAM BOARD 1 AND THIS PROM GOES INTO IC SOCKET 16
THIS CHIP WAS PROGRAMMED ON MARCH 23,1984
Set the switches on switch packages Sl through S5 using Table D and the 96K PRAM board illustration above.
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