Date: Sun, 15 May 94 15:49:21 -0600
From: Clifford T. Matthews <iclone!ctm AT cs DOT unm DOT edu>
To: djgpp AT sun DOT soe DOT clarkson DOT edu
Subject: Serial Port status?

Hi Folks,

About a month ago on this list there were some messages about serial  
port access under DJGPP.  I saved them for future reference and now  
I've just taken a look at the contents of aeasy102.zip and have some  
questions.

First off, I assume the reason for the dedicated TSR is one of  
performance.  With DJGPP 1.11, I should be able to use INT 14 and get  
serial port access directly, but presumably I won't get as good  
throughput as I would by using aeasy.  However, aeasy appears to only  
affect reception, not transmission.

Q1:  Does that mean that using aeasy will allow very fast  
transmission, but slower reception?

Q2:  Any idea of approximate throughput on a 66DX2 for:

	reading only via INT 14
	writing only via INT 14
	reading and writing simultaneously (alternating) via INT 14

	the same three but with aeasy

Michael Snowswell mentioned that aeasy doesn't have a programattic  
interface to allow you to set baud rates and such.  I couldn't find  
one either, but AE himself said "Say what? ... If I really left it  
out as args to the TSR ... I'll fix it".

Q3:  It appears that the TSR in aeasy102.zip doesn't allow the baud  
rate to be set.  Is there a newer TSR somewhere that does?

Q4:  How about a way to set the baud rate from within the program  
using the TSR?  Is this possible?

Q5:  Does aeasy work under DPMI?

Jan Kok reported problems associated with hangs when trying to read  
data that was there.  Michael Snowswell reported that he uses it at  
speeds up to 56kb without any trouble.

Q6:  Does anyone else still experience hangs using aeasy?

I will be adding serial port support to Executor, our Macintosh  
emulator, over the next week and I'm still deciding on a game plan.   
I don't know a whole lot about DOS programming, but it appears that  
except for the throughput problems, going directly with INT 14 might  
be the best bet.  However, I want to allow people to at least do  
reads at 38400, so aeasy is one possibility, as is writing the same  
sort of functionality into a library instead of a TSR.

Thanks for whatever information you can provide.

	--Cliff [ord T. Matthews]
	ctm AT ardi DOT com