Subject: Re: Hayes ESP users
To: Frederic Loyer <>
From: Michael L. VanLoon -- <>
List: port-i386
Date: 03/15/1995 14:23:58
>I ve got an 1 port ESP Hayes card and I'm really interested in testing 
>a specific driver for NetBSD.
>Unfortunatly, I've no technical documentation about its programmation,
>and only managed to port the ESPA utility (from the unassembled DOS
>utility) and get the card working as a 16550 UART.

There is no need for a special driver.  The card Just Works as a
16550, and it uses the entire 1024-byte FIFO.  The only thing you're
not getting is: you're not filling the FIFO with more than 16 bytes at
a time while sending (though this is a minor drawback), and the card
is not running in 16-bit mode, which would effectively double the
speed bus <-> FIFO, though I'm not sure this makes a big difference
either, since it's running significantly slower than an ISA bus,

It also has a DMA mode, but I'm not real certain that's of any benefit
to us, since it uses the same amount of bus bandwidth (being an ISA
card), and serial traffic is pretty low CPU demand compared to the
rest of the things the CPU does.

Anyway, the bottom line is that it will Just Work if you use it in
16550 mode, and the 1024-byte FIFO will keep you from dropping any
characters, even at 115200 bps on a slow machine.

Granted, a full-blown enhanced DMA ESP driver would be nice, down the
road.  But, since the card works well already, it definitely isn't a
high-priority item.

  Michael L. VanLoon                       
       --<  Free your mind and your machine -- NetBSD free un*x  >--
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