---
name: "ec"
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/ec/4"
---

# ec(4)

3Com EtherLink II (3c503) Ethernet device

## NAME

**ec** – 3Com EtherLink II (3c503) Ethernet device

## SYNOPSIS

**ec0 at isa? port 0x250 iomem 0xd8000 irq 9**

## DESCRIPTION

The **ec** device driver supports 3Com EtherLink II (3C503) Ethernet cards.

The EtherLink II supports two media types on a single card. All support the AUI media type. The other media is either BNC or UTP behind a transceiver. Software cannot differentiate between BNC and UTP cards.

The **ec** driver supports the following media types:

- 10base5

  Set 10base5 (thick-net) operation.

- 10base2

  Set BNC (10base2/thin-net) or UTP operation.

For more information on configuring this device, see [ifconfig(8)](/ifconfig/8.md). To view a list of media types and options supported by your card try “ifconfig \<device\> media”. For example, “ifconfig ec0 media”.

## DIAGNOSTICS

- ec0: wildcarded IRQ is not allowed

  The IRQ was wildcarded in the kernel configuration file. This is not supported.

- ec0: invalid IRQ \<n\>, must be 3, 4, 5, or 9

  An IRQ other than the above listed IRQs was specified in the kernel configuration file. The EtherLink II hardware only supports the above listed IRQs.

- ec0: failed to clear shared memory at offset \<off\>

  The memory test was unable to clear the interface's shared memory region. This often indicates that the card is configured at a conflicting *iomem* address.

## SEE ALSO

[ifmedia(4)](/ifmedia/4.md), [intro(4)](/intro/4.md), [isa(4)](/isa/4.md), [hostname.if(5)](/hostname.if/5.md), [ifconfig(8)](/ifconfig/8.md)