Mitsubishi Electric Apricot LS Pro, Hardware Technical Reference

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System Board
Contents
Chapter 1
Chapter 2
Chapter 3
Chapter 5
Chapter 6
Chapter 3
3/4 LS PRO HARDWARE TECHNICAL REFERENCE
Description
The following description of the system board should be read in conjunction with the
block diagram below. The diagram shows the peripheral areas of circuitry which are
connected to the CPU. For clarity, timing and control signals are omitted.
SA
LA
SD
LD
LOCAL DATA 0-15
LOCAL ADDRESS 0-23
SYSTEM ADDRESS 0-23
SYSTEM DATA 0-15
BUFFER
BUFFER
TOKEN RING
MODULE
CONNECTORS
IDE
CONNECTOR
FLOPPY
CONTROL
PERIPHERAL
CONTROL
AUDIO VGA
EXPANSION
ROM
KEYBOARD
MOUSE
CONTROL
REAL
TIME
CLOCK
PROCESSOR ETHERNET MEMORY
SCAMP
82C311
80387SX
BIOS
ROM
MA
The block diagram is a functional description of the system board and does not identify
specific chips.
The LS Pro system board uses highly integrated components, reducing the chip count
and the system board area, and increasing reliability. The VLSI SCAMP chipset
integrates much of the standard AT system board peripheral logic onto a single chip.
The processor and coprocessor are connected to a 16-bit local bus running at 33MHz.
Control logic for the local bus is integrated in SCAMP.
Memory addresses are generated by SCAMP and are routed to system memory on a
dedicated memory address bus. Memory data uses the local data bus.
The 82596 based Ethernet interface connects directly to the local bus allowing fast
transfers to and from system memory.
The BIOS ROM is addressed from the system bus and places its data on the local bus.
All other peripheral circuitry is connected to the system bus.
Coprocessor The system board includes a socket for an 80387SX coprocessor. This is a high
performance numeric coprocessor which further improves the performance of the
processing system in applications which perform many floating point arithmetic
operations.
The coprocessor has two I/O ports 00F0h and 00F1h which are used to control reset
and error latching. The coprocessor interface control logic is integrated in SCAMP.
If a coprocessor is fitted on the system board it should always be reset at the same time
as the processor.
System reset The system is automatically reset on power up. No external hardware reset facility is
provided. Some operating systems provide a software reset e.g. MS-DOS resets the
machine if CTRL, ALT and DEL are pressed at the same time.