---
name: "gsc"
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/gsc/4"
---

# gsc(4)

introduction to HP 9000/700 GSC bus support

## NAME

**gsc** – introduction to HP 9000/700 GSC bus support

## SYNOPSIS

**gsc\* at lasi?** **gsc\* at asp?** **gsc\* at wax?**

## DESCRIPTION

The General System Connect (GSC) bus is the core I/O bus for all HP 9000/700 workstations. All I/O subsystems connect to this bus. The devices can be either on separate chips, expansion cards or on an integrated megacell, like the LASI MBA.

The GSC bus is a 32-bit wide, address and data multiplexed bus. In its "standard" implementation it has a maximum throughput of 160MB/s, the "2x" implementation reaches up to 250MB/s. Some HPPA CPUs directly attach to this bus, namely the PA7100LC and PA7300LC.

As for the expansion cards, there are different form-factors, depending on bus-speed (standard or 2x) and specific models. The standard formfactor is the "EISA form-factor"; cards that look like typical EISA cards with a different connector (100-pin female EBBL). The Series 712 have their own special type of GSC expansion cards, called the "GIO form-factor", which is quite small and mostly has only one VLSI chip on it (in most cases LASI/WAX). Newer systems sometimes feature the "HSC formfactor", which is a 1U-VME card-like expansion card with a 100-pin male pin+socket connector. Mixing cards with different speeds is supported but downgrades the performance of the whole I/O-subsystem.

OpenBSD provides support for the following devices:

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

  Siemens PSB2160 audio codec

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

  serial communications interface

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

  PC-style keyboard controller

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

  CS4215/AD1849 audio

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

  introduction to HP-HIL support

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

  Intel i82596 Ethernet device

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

  parallel port driver

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

  Symbios/NCR 53C700 SCSI I/O Processor

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

  Symbios/NCR 53C710 SCSI I/O Processor

Some of these GSC devices also have PCI, EISA, or ISA equivalents. These are listed in [pci(4)](/pci/4.md), [eisa(4)](/eisa/4.md), or [isa(4)](/isa/4.md).

## SEE ALSO

[asp(4)](/asp/4.md), [cpu(4)](/cpu/4.md), [intro(4)](/intro/4.md), [lasi(4)](/lasi/4.md), [wax(4)](/wax/4.md)

## HISTORY

The **gsc** driver appeared in OpenBSD 2.6.