CL-PD6722 datasheet(22/128 Pages) CIRRUS

22 / 128 page

PRELIMINARY DATA SHEET v3.1

CL-PD6710/’22

ISA–to–PC-Card Host Adapters

May 1997

INTRODUCTION

3.1

System Architecture

This section describes PC Card basics, windowing,

interrupts, CL-PD67XX power management, socket

power management, write FIFO, bus sizing, pro-

grammable PC Card timing, and ATA and DMA

mode operation.

3.1.1

PC Card Basics

PCMCIA is an abbreviation for Personal Computer

Memory Card International Association. PC Card

Standard1 is a standard for using memory and I/O

devices as insertable, exchangeable peripherals for

PCs (personal computers) and handheld comput-

ers. For simpler end-user and vendor implementa-

tion of the standard, systems employing PC Card

Standard should also be backward-compatible with

industry-standard PC addressing.

The memory information for memory-type PC Cards

must be mapped into the system memory address

space.This is accomplished with a ‘windowing’ tech-

nique that is similar to expanded memory schemes

already used in PC systems (for example, LIM 4.0

memory manager).

PC Cards can have

attribute and common memory.

Attribute memory is used to indicate to host software

the capabilities of the PC Card, and it allows host

software to change the conﬁguration of the card.

Common memory can be used by host software for

any purpose (such as ﬂash ﬁle system, system

memory, and ﬂoppy emulation).

1 The CL-PD67XX is backward-compatible with PCMCIA

standards 1.0, 2.0, 2.01, and 2.1. The CL-PD67XX is

also compatible with JEIDA 4.1 and its earlier standards

corresponding with the PCMCIA standards above.

I/O-type PC Cards, such as modems, should also

be directly addressable, as if the cards were I/O

devices plugged into the ISA bus. For example, it

would be highly desirable to have a PC Card modem

accessible to standard communications software as

if it were at a COM port. For COM1, this would

require that the modem be accessed at system I/O

address 3F8h–3FFh. The method of mapping a PC

Card I/O address into anticipated areas of ISA I/O

space is done similarly to memory windowing.

I/O-type PC Cards usually have interrupts that need

to be serviced by host software. For the example of

a modem card accessed as if at COM1, software

would expect the modem to generate interrupts on

the IRQ4 line. To be sure all interrupts are routed as

expected, the CL-PD67XX can steer the interrupt

from the PC Card to one of several standard PC

interrupts (see Section 3.1.4 and the Interrupt and

General Control register on page 42).

3.1.2

CL-PD67XX Windowing Capabilities

For full compatibility with existing software, and to

ensure compatibility with future memory cards and

software, the CL-PD67XX provides ﬁve program-

mable memory windows per socket and two pro-

grammable I/O windows per socket. These windows

can be used by an inserted PC Card to access ISA

memory and I/O space.

Having ﬁve memory windows per socket allows a

memory-type card to be accessed through four

memory windows programmed for common mem-

ory access (allowing PC-type expanded-memory-

style management), leaving the ﬁfth memory win-

dow available to be programmed to access the

card’s attribute memory without disrupting the com-

mon memory in use.

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