Stack Boards; Stack Motherboard; Clock Board - HP 9030 Service Manual

Theory of Operation
2-11
Stack Boards
Board types and functions are described in the following paragraphs. Each board has a self-test that
runs on powerup or system reset. Self-tests are described in Chapter 3.
CPU Board
Two types of CPU board perform all the central processing for the computer. The first type of CPU
contains a clock buffer and a CPU chip. All CPU microcode, and the hardware to decode and
execute instructions, are included in the CPU chip.
The second type of CPU board contains an additional three math chips (add/subtract, multiply, and
divide) to provide floating point, 32 bit or 64 bit, double precision math solutions. The CPU sends
control information and data to the math chip registers. The answer is returned to the CPU a few
computer states later. These math chips are invisible to the operating system.
lOP Board
The lOP board performs I/O processing and drives the I/O bus. The lOP board actually consists of
two parts: the board assembly itself and an attached buffer printed circuit board. The buffer pc
board is attached to the lOP board by a 50-pin connector. Clamps and screws ensure a solid
physical connection.
The clock buffer and the I/O processor chip are on the lOP board. The buffer pc board contains the
five bi-directional buffer TTL packages that drive the I/O bus. The buffer pc board also contains
several resistor packages and a transistor package. The resistor paks terminate the I/O bus and its
characteristic impedance. The transistor pak holds the reset signal on the I/O bus during a power-up
and power-down sequence.
RAM Board
There are three types of RAM boards available for use in the stack. They can be installed in any
combination, but the 1 Megabyte boards must be used in pairs. The 256K byte RAM is a finstrate.
The 512K byte boards and 1 megabyte RAM boards are polystrates. Each board has a memory
controller, RAM chips, and clock buffers.
Load Board
The Load Board consists of load resistors to ensure the correct power supply load for certain stack
configurations. The load board will be used when:
• The stack consists of one CPU, one lOP, and one 512K RAM board .
• The stack consists of one CPU, one lOP, and six or less 1 Megabyte RAM boards.
Stack Motherboard
The stack motherboard interconnects the 12 board slots via the memory processor bus. The two
25-pin connectors at the bottom of the stack provide power and some control signals to the stack
motherboard.
Clock Board
The clock board provides clock signals to the processor. This board electrically interconnects to the
stack motherboard via a 9-pin connector. The clock board attaches to the stack motherboard with
two screws.