2-3
ARCHITECTURAL OVERVIEW
2.2 INTEGRAT ED PERIPH ERALSThe Intel386 EX processor integrates both PC-compatible peripherals (Table 2-1) and peripheralsthat are specific to embedded applications (Table 2-2).Table 2-1. PC-compatible Peripherals
Name Description
Interrupt
Control Unit
(ICU)
Consists of two 82C59A programmable interrupt control lers (PICs) configured as master
and slave. You may cascade up to six external 82C59A PICs to exp and the external
interrupt lines to 52. Refer to Chapter 9, “INTERRUPT CONTROL UNIT.”
Timer/counter
Unit (TCU) Provides three independent 16-bit down counters. The programmable TCU is
functionally equivalent to three 82C54 counter/timers with enhancements to allow
remapping of peripheral addresses and interrupt assignments. Refer to Cha pter 10,
“TIMER/COUNTER UNIT.”
Asynchronous
Serial I/O
(SIO) Unit
Features two independent universal asynch ronous receiver and transmitter (UART)
units which are functionally equivalent to National Semiconductor’s NS16450. Each
channel contains a baud-rate generator, transmitter, receiver, and modem con trol unit.
Receive and transmit interrupt signals can be connected to the ICU controller an d DMA
controller. Refer to Chapter 11, “ASYNCHRONOUS SERIAL I/O UNIT.”
Direct Memory
Access
(DMA)
Controller
Transfers internal or external data between any combination o f memory and I/O devices
for the entire 26-bit address bus. The two independent channels operate in 16- or 8-bit
bus mode. Buffer chaining allow s data to be transferred into noncon tiguous memory
buffers. The DMA channels can be tie d to any of the serial devices to support high data
rates, minimizing processo r interruptions. Provides a special two-cycle mode that uses
only one channel for memory-to-memory tran sfers. Bus arbitration logic resolves priori ty
conflicts between the DMA channels, the refresh control unit, an d an externa l bu s
master. SIO and SSIO interrupts can be conne cted to DMA for high-speed transfer s.
Backward compatible with 8237A. Refer to Chapter 12, “DMA CONTROLLER.”