On Tue, 5 May 2026 17:58:56 -0700
Fred <fred@???> wrote:

> Hi,
>
> I sometimes need more than the built in serial port so I bought a PCI
> 4-port serial card.
>
> The kernel apparently recognizes the card.
...............................
> I haven't been able to find out what error code -28 is other than out
> of space.
>
> How can the fourth port be assigned as: /dev/ttyS4?

My 2c guess is does /dev/ttyS4 exist?
At one stage you had to modify a setting and simply restart your system
as some /dev files were built as needed.

My excalibur system only has four defined.

terryc