Subject: Re: How about to config Hayes ESP with glue device rather than magical option?
To: Chris G. Demetriou <>
From: Michael L. VanLoon -- <>
List: current-users
Date: 09/10/1997 13:12:59
>> > While i'm at it, it really should be just:
>> > hayesesp0 at isa0 port ....
>> > I.e. no 'com' at all.

>> Do you mean that even if the card is operated in ns16x50 compatible
>> mode, it should be the device different from `com'?

>If the card is to be operated in 16x50-compatible mode, it shouldn't
>have any device _other_ than 'com', should it?  If it's to be run in
>"extended" mode, hayesesp should drive it.  If it's to be run in
>compatible mode, 'com' should drive it.  Really, both 'com' and
>'hayesesp' should probably be front-ends to a single back-end driver.
>(I don't know how incompatible "extended" mode is; i've never seen one
>of these cards, let alone the docs.)

There are really two different concepts of "extended" mode.

In 16550-compat mode, the current com driver, when built with "options
HAYESP" will recognize ESP cards and use larger buffers (256-byte
lowater, 768-byte hiwater receive, if I remember right, and a
1024-byte send buffer).  That's the only current "enhancement".

However the true "extended" mode as Hayes intended it is a completely
non-compatible mode that uses 16-bit accesses with optional ISA DMA.
This would be cool to have a driver for, but none currently exists in
the *BSDs (though it's rumored that a Linux driver does this).

The former mode gives most of the benefit of the card without having a
separate, totally different driver.

  Michael L. VanLoon                 
      Contract software development for Windows NT, Windows 95 and Unix.
             Windows NT and Unix server development in C++ and C.

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