Cpu Assembly; Cpu; System Memory - HP PageWriter XL M1705B Service Manual

CPU Assembly
This discussion of the CPU assembly covers the following circuits:
n
CPU
1 System Memory
n
ROM
n
I/O Control
w Digital Signal Processor
n
Flexible Disk Drive (M1700A and M1701A only)
H System Expansion Connector
The block diagram in Figure 5-4 shows these circuits and how they
interconnect.
CPU
The microprocessor used in the CPU is the Intel 80376@, a 32-bit
processor with a 16-bit data bus and 24-bit acldress bus. The CPU
address and data buses go to the DRAM block, the system expansion
connector, and to latches and buffers, as shown in Figure 5-4.
Address latches buffer the address signals in order to drive a
larger number of devices and latch the addresses. Data buffers
(transceivers) allow the CPU to communicate with a larger number
of devices, and ensure that the CPU data bus is driven at the proper
times. The programmable interrupt controller (PIC) accepts and
prioritizes interrupt requests and generates the interrupt signal to the
I
microprocessor.
5-8 Theory of Operation