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

# esp(4)

ESP NCR 53c94 on-board or SBus SCSI interface

## NAME

**esp** – ESP NCR 53c94 on-board or SBus SCSI interface

## SYNOPSIS

**dma\* at sbus?**               (SBus SCSI) **esp\* at dma?**                (two flavours) **esp\* at sbus?**               (depending on model)

## DESCRIPTION

The **esp** is an on-board or SBus SCSI controller based on the NCR 53c94 chip, found on some Sun UltraSPARC workstations.

## DEVICE FLAGS

- Bits 0-15

  Disable disconnect/reselect for the corresponding target

- Bits 16-31

  Disable synchronous negotiation for target "\[bit - 16\]"

The **esp** device flags may be OR'd together to enable any combination of the features listed above. Targets 4 through 7 typically have disconnect/reselect enabled on the premise that tape devices normally have one of these targets. Tape devices should be allowed to disconnect for the SCSI bus to operate acceptably.

## SEE ALSO

[cd(4)](/cd/4.md), [ch(4)](/ch/4.md), [intro(4)](/intro/4.md), [sbus(4)](/sbus/4.md), [scsi(4)](/scsi/4.md), [sd(4)](/sd/4.md), [st(4)](/st/4.md), [uk(4)](/uk/4.md)

## HISTORY

OpenBSD support for the **esp** first appeared in OpenBSD 3.0.