From: kunst AT prl DOT philips DOT nl (Pieter Kunst)
Subject: Re: analog I/O with go32
To: Piet=Mertens AT users (Piet=Mertens)
Date: Tue, 1 Jun 93 15:38:27 METDST
Cc: pmertens AT cc3 DOT kuleuven DOT ac DOT be, djgpp AT sun DOT soe DOT clarkson DOT edu (DJGPP users list)
Mailer: Elm [revision: 70.85]


Piet Mertens writes:

> Does someone have experience with programming analog-to-digital
> and digital-to-analog converters with DJGPP ?

Yes. I use a card from Keithley (DAS1602).

> For high conversion rates (typ. 10 kHz), a simple polling procedure will 
> probably loose samples while the memory buffer is being copied to virtual
> memory (expanded memory or disk memory) by go32.

Samples with the card I use can be obtained using 'inportb()' and
'outportb()' functions supplied with GO32 in 'libpc.a' using '-lpc' switch.

> I don't know whether DMA can access expanded memory directly, but even if
> this is the case, there must be a way to "wire" those memory blocks
> (to avoid them from being swapped out by go32), as is done on certain Unix
> systems.  Will go32 2.0 have a provision for "wiring" memory blocks ?  

Yes, it will (hopefully). This is one of the most common questions.

> A pointer to available source code would be mostly appreciated.

To access (extended) memory, you'll have to change GO32 (1.09, 1.10) itself.
First you have to set up the appropriate page table entries for the memory. 
This should be done in 'go32/paging.c'. I'll advise you to obtain a copy 
of the 'Intel 386 programmers' reference' for more details.
You also need Turbo C to recompile GO32 (preferably the old version 2.0).

Or you can wait for GO32 version 2.0 to be released... ;-)

--

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