Intel 386 manual Coprocessors, Integrated System Peripheral

SYSTEM OVERVIEW

Table 1-1. Intel386™ Family System Components

Component	Description
Inte1386'MOX Microprocessor	32-bit high-performance microprocessor with on-chip
	memory management and protection
Intel38TM OX Math Coprocessor	Performs numeric instruction in parallel with Intel386 OX
	microprocessor; expands instruction set
82380 Integrated System Peripheral	Provides 32-bit high-speed direct memory access, inter-
	rupt control, and interval timers
82385 Cache Controller	Provides cache directory and management logic
8259A Programmable Interrupt Controller	Provides interrupt control and management
82350 EISA Chip Set	Extends the 32~bit transfer capability of the Intel386 DX
	microprocessor to the I/O expansion bus
82311 MCA Chip Set	Provides for the design of a very high performance
	Micro Channel compatible PS/2 system
825960X LAN Coprocessor	Performs high-level commands, command chaining and
	interprocessor communications via shared memory

microprocessor can save the state of one task (all registers), load the state of another task (all registers, even segment and paging registers if required), and resume execution in less than 14 microseconds (at 20 MHz). For less sophisticated task and interrupt handling, the latency can be as short as 2.9 microseconds (at 20 MHz).

1.2 COPROCESSORS

The performance of most applications can be enhanced by the use of specialized copro- cessors. A coprocessor provides the hardware to perform functions that would otherwise be performed in software. Coprocessors extend the instruction set of the Intel386 DX microprocessor.

The Intel386 DX microprocessor has a numeric coprocessor interface designed for· the Inte1387 DX math coprocessor. For applications that benefit from high-precision integer and floating-point calculations, the numeric coprocessor provides full support for the IEEE standard for floating-point operations. The Intel387 DX math coprocessor is soft- ware compatible with the 80287 and the 8087, earlier numeric coprocessors.

1.3 INTEGRATED SYSTEM PERIPHERAL

A DMA (Direct Memory Access) controller performs DMA transfers between main memory and an I/O device, typically a hard disk, floppy disk, or communications chan- nel. In a DMA transfer, a large block of data can be copied from one place to another without the intervention of the CPU.

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