CL-PD6710/’22
ISA–to–PC-Card Host Adapters
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.
3. 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
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).
PCMCIA is an abbreviation for Personal Computer
Memory Card International Association. PC Card
Standard 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.
1
3.1.2
CL-PD67XX Windowing Capabilities
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).
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.
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).
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.
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.
22
May 1997
INTRODUCTION
PRELIMINARY DATA SHEET v3.1
CIRRUS [ CIRRUS LOGIC ]
