Subject: Re: Gateway 2000 keyboard vs ddb
To: NetBSD 386 Port <port-i386@NetBSD.ORG>
From: Hellmuth Michaelis <>
List: port-i386
Date: 03/21/1995 20:54:59
>From the keyboard of Mike Long:

> >>>Yes, pcvt is using delay(6) calls, why do you recommend 7 or higher ?
> >
> >>According to _The Undocumented PC_ by Frank Gilluwe (sp?) the spec for
> >>the PS/2's keyboard controller requires that there be a 7ms delay
> >>between accesses to the controller's status port and its control port.
> >
> >There's only one delay(6) in pcvt, and it's between accesses to the 
> >status port and the _data_ port.  What does the book say about the
> >data port?  Does it say something about delaying between accesses to
> >the control port and the status port?

The Undocumented PC (Frank van Gilluwe) says on page 273:

"Before reading any information from port 60h, the controller output buffer
 status should be checked to ensure a byte is available. Read port 64h to
 get the status and check that bit 0 is 1. If bit 0 is 0, then no valid 
 information is available. MCA systems with a type 1 controller must wait
 at least 7 microseconds after bit 0 transitions from 0 to 1 before reading
 the data from port 60h."

I have not found references to other delays which might be necessary.

Further down in the text is a code fragment to detect MCA type 1 and 2
motherboard controllers (!), it would be interesting to see the results
of running this fragment on the Gateway 2000 machines in question!

Hellmuth Michaelis        GFKT HCS Computertechnik GmbH        Hamburg, Europe
                     We all live in a yellow subroutine, yellow subroutine ...