---
name: "eisa"
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/eisa"
---

# eisa(4)

introduction to EISA bus support

## NAME

**eisa** – introduction to EISA bus support

## SYNOPSIS

Machine-dependent; depends on the bus topology and EISA bus interface of your system. Typical EISA buses are either connected directly to the main system bus, or via an PCI to EISA bridge. See the [intro(4)](/intro/4.md) documentation for your system for details.

## DESCRIPTION

OpenBSD includes a machine-independent EISA bus subsystem and several machine-independent EISA device drivers.

OpenBSD provides support for the following devices. Note that not all architectures support all devices.

### Disk and tape controllers

- [cac(4)](/cac/4.md)

  Compaq Smart Array 2/3/4 SCSI RAID controller

### SCSI interfaces

- [ahc(4)](/ahc/4.md)

  Adaptec VL/EISA/PCI SCSI interface

- [uha(4)](/uha/4.md)

  Ultrastor SCSI interface

### Network interfaces

- [ep(4)](/ep/4.md)

  3Com EtherLink III and Fast EtherLink III 10/100 Ethernet device

Note that most or all EISA devices also have PCI or ISA equivalents. These are listed in [pci(4)](/pci/4.md), [isa(4)](/isa/4.md), or [isapnp(4)](/isapnp/4.md), respectively. The manual pages for each individual driver also lists the supported bus variants.

## SEE ALSO

[intro(4)](/intro/4.md)

## HISTORY

The machine-independent EISA subsystem appeared in OpenBSD 1.2.