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NM95MS16

Plug and Play Front-End Devices for ISA-BUS Systems

Fairchild Semiconductor 

Timing Diagrams

AEN

SA[0:11]

IORD*

IOWR*

READ DATA

SD[0:7]

WRITE DATA

SD[0:7]

Timings for ISA Read/Write Cycle

tAEN

tAC

tWD

VALID ADDRESS

tRVD

tAH

VALID

tRDH

tWDH

SA[0:11]

IOCS[0:1]*

(addr decode only)

IORD*

IOWR*

IOCS[0:1]*

(Qualified with CMD)

Decode Delay for Chipselect Generation

tCSA

VALID ADDRESS

tCSA

tCSC

tCSC

Propagation Delay for IRQ/DRQ/DACK

DS012601-4

DS012601-5

IRQin

tIDD

DRQin

ISADACK

IRQout

DRQout

DACKout

tIDD

DS012601-6

INTRODUCTION

The NM95MS16 is a single-chip solution for the ISA Plug and Play

(PnP) specification. It implements the complete state machine

and the necessary logic for supporting configurable Interrrupts

and DMA channels on the ISA bus for one logical device. Apart

from providing “PnP” capability, it has built-in EEPROM that

eliminates external EEPROM. This device is available in a space

saving 48-pin Thin Quad Flat Pack (TQFP) package.

Functional Description

NM95MS16 has two modes of operation, viz, “DMA mode” and

“Extended Interrupt mode”. These modes are programmed using

the mode select (MS) bits in one of the configuration registers

(Refer to the NM95MS16 User’s guide for detailed information).

Each of these modes are discussed below.

DMA Mode

In the DMA mode, support is provided for

1. One on-board DMA request that is switchable to any two

DMA channels on the ISA bus.

2. Two on-board interrupt request lines switchable to any six

IRQ lines on the ISA bus.

3. Two programmable I/O chip selects for on-board logic.

Figure 1 shows a Block Diagram of NM95MS16 configured for

DMA Mode.

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