---
name: "clock"
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/clock/4"
---

# clock(4)

real-time clock

## NAME

**clock**, **rtc** – real-time clock

## SYNOPSIS

**clock\* at sbus?** **clock\* at ebus?** **clock0 at fhc0** **rtc\* at ebus?**

## DESCRIPTION

The **clock** device provides support for the real-time clocks based on the following chips:

- Mostek MK48T02

- Mostek MK48T08

- Mostek MK48T18

- Mostek MK48T59

The **rtc** device provides support for the real-time clock based on the following chips:

- Dallas/Maxim Semiconductor DS1287

- Acer Labs M5819

- Acer Labs M5823

- Texas Instruments BQ4802

## SEE ALSO

[ebus(4)](/ebus/4.md), [fhc(4)](/fhc/4.md), [intro(4)](/intro/4.md), [sbus(4)](/sbus/4.md)