---
name: "osiop"
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/osiop"
---

# osiop(4)

Symbios/NCR 53C710 SCSI driver

## NAME

**osiop** – Symbios/NCR 53C710 SCSI driver

## SYNOPSIS

**osiop\* at gsc? irq 9**                   (hppa)

## DESCRIPTION

The **osiop** driver provides support for the Symbios/NCR 53C710 SCSI controller chip.

The Symbios/NCR 53C700 SCSI controller is handled by the [oosiop(4)](/oosiop/4.md) driver, while the Symbios/NCR 53C8xx PCI SCSI host adapters are handled by the [siop(4)](/siop/4.md) driver.

## CONFIGURATION

The **osiop** driver supports the following **flags** for use in [config(8)](/config/8.md) files:

- bits 0-7:

  disable disconnect/reselect for the corresponding SCSI target

- bits 8-15:

  disable synchronous negotiation for SCSI target

- bits 16:

  disable DMA interrupts

"Target" is synonymous with SCSI ID number.

Note that SCSI tape drives should be allowed to perform disconnect/reselect or performance will suffer.

## SEE ALSO

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

## HISTORY

The **osiop** driver first appeared in NetBSD 1.6.

The original NCR 53C710 driver appeared in NetBSD 1.0 amiga port, and Izumi Tsutsui ⟨*tsutsui@ceres.dti.ne.jp*⟩ modified the driver and made it machine-independent.