---
name: "pcexmem"
section: "4"
platform: "openbsd"
package: "man"
version: "8.0-current-20261101"
release: "OpenBSD 8.0-current (2026-11-01)"
platforms: ["openbsd"]
url: "https://new.carta.tech/pcexmem"
---

# pcexmem(4)

NEC PC-9801 extension board slot

## NAME

**pcexmem**, **pcexio** – NEC PC-9801 extension board slot

## SYNOPSIS

**pcex0 at cbus0**

## DESCRIPTION

The file */dev/pcexmem* is an [mmap(2)](/mmap/2.md) capable interface to the memory area of the installed board at "NEC PC-9801 extension board slot" on LUNA-88K2. Byte offsets in this file are interpreted as relative memory addresses of the installed board. The range should be between 0x0 and 0xffffff.

The I/O port area of the installed board is accessed via the file */dev/pcexio* in the same manner as */dev/pcexmem*. The range should be between 0x0 and 0xffff.

The following [ioctl(2)](/ioctl/2.md) calls apply to */dev/pcexmem* and */dev/pcexio* in order to handle interrupts of this extension slot. Currently 7 levels of interrupt (0 to 6) are supported.

- PCEXSETLEVEL *u\_int \**

  Register the specified interrupt level with this driver to handle.

- PCEXRESETLEVEL *u\_int \**

  Unregister the specified interrupt level with this driver.

- PCEXWAITINT *u\_int \**

  Wait for the interrupt with the specified level.

## FILES

- */dev/pcexmem*

  - */dev/pcexio*

  ## ERRORS

- \[EWOULDBLOCK\]

  PCEXWAITINT timeouts (currently 1 second).

## SEE ALSO

[ioctl(2)](/ioctl/2.md)

## HISTORY

The */dev/pcexmem* and */dev/pcexio* files first appeared in OpenBSD 5.6.