Table 3-2. Mode1330/350 Ram Boards - HP 330 Service Information Manual

RAM Boards
Introduction
Model 330/350 RAM boards consists of one controller board and two add-on boards listed in
Table 3-2.
Table 3-2. Model 330/350 RAM Boards
Product No. Product Name
HP98258A 4 Mbyte RAM Controller Board
HP98258B 4 Mbyte RAM Add-On Board
HP98258C 12 Mbyte RAM Add-On Board
Either a 4 or 12 Mbyte Add-On board can be added to the 4 Mbyte RAM Board. With this
arrangement, 4, 8 or 16 Mbytes of RAM in each system slot is possible. Maximum RAM in the
system (inside the computer) is 32 Mbytes (two 16 Mbyte 2-board assemblies) for a Model 350.
For Model 330 computers, 8 Mbytes of RAM is supported; 4 Mbytes on the processor board
and one 4 Mbyte RAM controller board.
HP 98256A 256 Kbyte and HP 98257 A 1 Mbyte RAM Cards are not supported on these com-
puters; they won't function correctly.
Refer to Figure :3-19 for the RAM board block diagram.
RAM Architecture
Each RAM controller is a 4 Mbyte with parity RAM board for the Model 330/350 computers.
The 4 Mbyte or 12 Mbyte add-on boards provide an additional 4 or 12 Mbytes of memory when
installed on the controller board. When a 4 Mbyte add-on is attached to a 4 Mbyte RAM
controller board, an 8 Mbyte RAM 2-board assembly is formed. In the same manner, if the 4
Mbyte add-on is used, a 16 Mbyte 2-board RAM assembly is formed.
The RAM controller board contains the control and interface circuits used for its memory and
any add-on RAM board. In Model 350 computers, the board uses two busses, the DIO-II (the
32-bit extension to the DIO bus), and the systern bus (a high speed memory bus between the
RAM and Model 350 processor board). When running with a Model 350 processor, most data
transfers will take place over the system bus. When the system bus is not used, as with the
Model 330, transfers will take place on the DIO-II bus. In addition, all DMA transfers take
place on the DIO-II bus.
86 Functional Description