82C836 데이터 시트보기 (PDF) - Unspecified

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82C836

Single-Chip 386sx AT

Unspecified 

s Architectural Overview

82C836 CHIPSet Introduction

Bus Conversion----Whenever the CPU attempts to transfer a 16-bit even-address word

to or from an 8-bit resource, the 82C836 converts the 16-bit CPU cycle into two

consecutive 8-bit cycles. The CPU is delayed by means of wait states until both 8-bit

cycles have been completed. Bus conversion by the 82C836 can occur on either I/O or

memory cycles, but only on CPU initiated cycles, not on DMA or Master cycles.

The following summarizes all possible cycles types in a SCATsx AT-compatible

architecture.

• CPU initiated local cycles (no command on AT bus)

° Local DRAM read or write

° Interrupt acknowledge

° Halt/Shutdown

• CPU initiated AT bus cycles (command generated on AT bus)

° On-board ROM read or write

° On-board I/O read or write

° AT bus memory read or write

° AT bus I/O read or write

• DMA

° Memory to I/O (simultaneous memory read and I/O write)

° I/O to memory (simultaneous I/O read and memory write)

• Master

° Memory read or write (may access on-board DRAM and ROM)

° I/O read or write

• Refresh

° Normal (system initiated)

° Master initiated

• Additional variations on the above types

° Resource: 8/16 bit, memory or I/O, on-board or AT bus

° Data transfer size: byte or word

° Address: even or odd, first 1MB or not

° Delay or speed-up via IOCHRDY or 0WS

1 -4 Revision 3.0

PRELIMINARY

Chips and Technologies, Inc.

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