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From: acliu@skat.usc.edu (Alejandro Liu)
Newsgroups: comp.sys.cbm
Subject: Re: vt emulator
Summary: 2400bd, slow drives
Keywords: 2400bd prescaler values needed
Message-ID: <18570@usc.edu>
Date: 17 Jul 89 17:26:27 GMT
References: <4394@sdcc3.ucsd.EDU> <4355@merlin.usc.edu> <17640@gryphon.COM> <8403@batcomputer.tn.cornell.edu>
Sender: news@usc.edu
Reply-To: acliu@skat.usc.edu (Goofie man)
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In article <8403@batcomputer.tn.cornell.edu> pwong@batcomputer.tn.cornell.edu (Patrick Wong) writes:
>In article <17640@gryphon.COM>, brendan@gryphon.COM (Brendan Kehoe) writes:
>> source that would do (theoretically) 4800, and mentioned that it could be
>> hyped up to 9600...since, if my memory serves me right, I remember either Geoff
>
>There are programs that do 2400 on C64.  But I think the tricky
>part is to find something that can do 2400 *AND* 
>has a 80 col. mode for C64 (a perfect vt emulator, that is)
>at the same time !  Any comment ?

The maximun pratical speed for the C64 is(can?) only be 2400bd,
because most (if not all) operations in the C64 are tuned for that.
For example, when doint file transfers with any protocol, the computer
expends quite some time doing disk access.  Seems to me that the baud
rate of the Serial Disk Port is around 3000bd, so stepping up to
around 4800bd, in a file transfer, the speed improvement would be
around 40% instead of a 100%, that you would think.  The fact that the
C64 can't do file access while reading the modem is the reason for
this, and the reason why we cannot have a streamming protocol for the
C64.

Now, for a request.  I have been writing a very simple term program
(Just as an exercise) and I don't seem to be able to do 2400bd.  First
I got 300bd right.  then to do 1200bd, I had to change the
Non-Standard Bit timing register (661) and the Baud pre scaler value
at 665.  what I would want to know is do you only need to change this
values to do 2400bd (And what are this values supposed to be?) and if
not, what other things you need to do to get 2400bd?

 
                    acliu@skat.usc.edu (Alejandro Liu) 
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