---
name: "gscsio"
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/gscsio"
---

# gscsio(4)

National Semiconductor Geode SC1100 I2C controller

## NAME

**gscsio** – National Semiconductor Geode SC1100 I2C controller

## SYNOPSIS

**gscsio\* at isa?** **iic\* at gscsio?**

## DESCRIPTION

The **gscsio** driver provides support for the National Semiconductor Geode SC1100 System-on-Chip Super I/O module. The Super I/O (SIO) module incorporates one serial port, an infrared communication port, two ACCESS.bus interface (ACB) ports, system wakeup control (SWC), and a real-time clock (RTC). Only the ACCESS.bus interface is currently supported.

ACB is a two-wire synchronous serial interface compatible with the Philips' I2C bus, and can be accessed through the [iic(4)](/iic/4.md) framework. The **gscsio** driver programs the ACB port to work with a standard I2C frequency 100kHz.

## SEE ALSO

[iic(4)](/iic/4.md), [intro(4)](/intro/4.md), [isa(4)](/isa/4.md)

## HISTORY

The **gscsio** driver first appeared in OpenBSD 3.6.

## AUTHORS

The **gscsio** driver was written by Alexander Yurchenko ⟨*grange@openbsd.org*⟩.