## Input/Output Device Driver Reference

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### Implementation Limitations and Restrictions

There are some restrictions on OS/2 PCMCIA client device drivers. These restrictions define Card Services support. The following can be supported by Card Services:

A maximum of four adapters

A maximum of eight sockets

A maximum of 16 clients

A maximum of four Socket Services drivers

A maximum of 16 memory technology drivers

A maximum of 16 memory handles

A maximum of 16 erase queues

A maximum of 16 regions

A maximum of 16 partitions

A maximum of seven windows per socket

The maximum window count is further defined such that five are memory windows (four for clients and one for Card Services), and two are I/O windows.

The following are not supported or provided by Card Services:

Paged memory windows

ROM BIOS Socket Services

Power management support. Even though some of the interfaces have power management definitions, the values are ignored by Card Services. For future compatibility, the power management bit always should be reset to 0.

Write protection. Even though some of the interfaces have write-protect definitions, the values are ignored by Card Services. For future compatibility, the write-protect bit always should be reset to 0.

The following additional restrictions apply to client device drivers that manage PCMCIA cards with secondary storage devices:

During device-driver initialization, the PCMCIA secondary storage card might not be present, but the device driver must still claim the required number of drive letters that it supports.

Multi-partitioned cards must have a drive letter assigned to each partition for the partition to be accessible.

All secondary storage cards are treated as removable media. This prohibits enhanced performance from file systems using cached support.