Table 3-3. Hp 98258A/B/C Ram Configuration - HP 330 Service Information Manual

RAM Configuration
Mernory configuration and addressing is set by ten address switches on the HP 98258A 4 Mbyte
RAM board. These switches determine the top address of a 4, 8, or 16 Mbyte block of RAM.
When the Model 330 is configured, remember the 4 Mbytes of processor on-board RAM that
must be contiguous with the 4 Mbyte RAM controller board if it's installed.
One or two 4 Mbyte RAM controller boards are supported on Model 350 conlputers. Only one
is supported on Model 330s.
Setting Address Switches
RAM assemblies (either one of the three combinations of HP 98258A/B/C RAM boards must
be configured on address boundaries equal to the RAM on the assenlblies, In other words, 4
Mbyte assenlblies can only be addressed to every 4M addresses starting from the top of RAM;
8 Mbyte 2-board assemblies at every 8M address; 16 Mbyte 2-board assemblies at every 16M
address.
Ten RAM configuration switches (S31 (MSB) through S22 (LSB)) are used on the HP 98258A
RAM Controller Board. They determine the addresses used on the assembly and are set to the
top address in the block of RAM the assembly will respond to.
Switches are set to one of the 4 Mbyte RA~1 blocks starting at the top of RAM, address
FFFFFFFF. Only the three most significant digits (MSD) of hexadecimal addresses are affected.
As the first eight switches (S31 through S24) represent the two MSDs, the last two switches
(S23, S22) can only change the third hexadecinlal MSD by 4M addresses; the lower two binary
positions of the third hexadecimal digit are inlplied as 1. Therefore, RAM is addressed in 4
Mbyte blocks.
Table 3-3 lists all possible configuration switch settings for a Model 350 computer. As the Model
330 is limited to 8 Mbytes of RAM, only the top two switch settings are possible.
Table 3-3. HP 98258A/B/C RAM Configuration
Decimal 3 Hex Switch
Address
MSDs Settings
4294967295 FFF 1111111111
4290772991 FFB 1111111110
4286578687 FF7 1111111101
4282384383
FF3
1111111100
4278190079 FEF 1111111011
4273995775
FEB
1111111010
4269801471 FE7 1111111001
4265607167 FE3 1111111000
Functional Description
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