>Date: Wed, 14 Sep 1994 15:33:49 -0400
>From: John Brezak <brezak@apollo.hp.com>

>> I think there was some discussion about this before; I remember some agreemen
>t
>> that access to the MIDI UART could be made general, but playing MIDI files
>> was still an open issue.
>I'm wondering about timing issues in playing MIDI. Does anyone know what
>constraints are present as far as timing in MIDI ?

It's just a UART, but it uses a weird bit rate: 31250 bps.  Also like
a regular UART, the MIDI port (at least on the PSS) cannot use DMA; so
expect some CPU loading.

>> It might be worthwhile to make a separate game port driver
>> one as well.  I was under the impression that the hardware interface was the
>> same, as they all have to be accessed the same way under DOS.

Yes.  A game port driver should be simple, but: You write port 0x201,
then you spin while reading port 0x201 until the appropriate bits go
back to zero.  The nasty thing about it is that you have to turn
interrupts off during this process, and the results you get are
proportional to the CPU's clock speed, etc.

>have a generic ad1848 driver that can be shared between the pss and wss (and
>possible the new GUS). Also the CD rom port should be able to use the 'mcd'

If I remember correctly the new GUS uses a Crystal Semiconductor
CS4231 codec (boo, hiss :), which is somewhat different from the '48.
-- 
Mike Long                                         Mike.Long@Analog.com
VLSI Design Engineer                    (PGP 2.6 public key available)
Analog Devices, CPD Division
Norwood, MA 02062 USA                assert(*this!=opinionof(Analog));