Re: Modem for apple2gs

[CUTblakeney@home.com (Jeff Blakeney)]

On 25 May 1999 04:42:40 GMT, supertimer@aol.com (Supertimer) wrote:

>It depends.  Under GS/OS programs like Spectrum, speed might be
>an issue because of interrupt robbing processes such as menu bar
>clocks, etc.
>
>However, I have found that even with the accelerator turned off,
>the IIGS has no problem with a 56k connection to a PC.  You can
>tell it is faster by comparing a IIGS to PC connection at 38.4k
>and one at 56k.  This is done in ProTERM 3.1 directly booting into
>ProDOS 8 (or a shift-boot, then launching ProDOS 8 from Finder).
>
>It seems that in this one instance, the 8-bit ProTERM 3.1 is ideal.
>
>I am not surprised that the IIGS, even an unaccelerated one, can
>easily do 56k.  After all, SCSI through the IIGS is several orders
>of magnitude faster.  Even AppleTalk and the IIGS floppy drives
>are several times faster.  The IIGS has no trouble transferring info
>at the paltry 56k speed.
>
>56kbaud is not fast.  It only sounds fast because modems themselves
>are inherently slow.  ;-)

The problem isn't with it being able to handle a 57,600 bps transfer
rate, it is in taking full advantage of that transfer rate.

What I mean is that when I do null-modem transfers between my PC and
my IIgs using a port speed of 57,600 bps I can get a maximum transfer
rate of 5760 cps (57,600 / 10 ; dividing by 10 because every character
consists of 10 bits, 1 start bit, 8 data bits and 1 stop bit).  I
believe even directly booting into ProDOS 8 and using ProTerm v3.0 the
fastest rate I've ever seen is around 3500 cps.

This means that my 8 MHz IIgs is only making use of around 60% of the
transfer rate.  30-40% is being wasted while my IIgs is doing stuff
with the data it has received.

Once I up the speed on my ZipGS I'm sure my transfer rates will
improve but I don't think my IIgs will ever take full advantage of a
57.6 kbps connection.

It could be the way communications programs are written but I've yet
to see full use of my transfer rate.

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