Re: 5.25 drive issue w/ IIgs & sys 6.01

[CUTjefbla@bconnex.net (Jeff Blakeney)]

On Fri, 8 Jun 2001 21:51:31 +1000, "Mark Cummings"
<NOTfigjams@primus.com.au> wrote:

>I can only talk between my PC & Mac, or PC & GS, or GS and Mac at 9600. It
>works reliably. As soon as I try 19200 or higher I get garbage. I even get
>this limit between the GS and Mac using a printer cable. The PC-GS cable is
>home made the PC-Mac is an off-the-shelf PC-Mac serial cable. My GS is a
>ROM1. On the PC I use Hyperterminal, On the Mac I use ClarisWorks Terminal.
>On the GS I use AppleWorks GS Terminal.
>Can you elaborate on your cable. Also what ROM is your GS ?
>Perhaps I should try different GS software, this could be the choke,
>although it doesn't explain the slow transfer between PC and Mac.
>The Mac-GS bottleneck was fixed when I put AppleTalk on both, now I get
>effective throughput of about 100Kb/s on phone cable.

and

On Fri, 08 Jun 2001 16:53:45 GMT, "william strutts"
<wrstrutts1@home.com> wrote:

>My IIgs is a ROM 3 machine and the cable is a mini-8 to
>RS-232c 9-pin which was designed to work with a Mac
>and a Uninteruptable Power Supply.  I would assume that
>this is a null modem cable.  The terminal protocol is as
>follows:
>
>8 bits/1 stop/no parity
>Xon/Xoff
>36K
>Xmodem
>
>Appleworks GS doesn't support transfers faster than 19200.
>I currently use Z-Link which supports up to 56K transfers but
>it won't work with 56K with the PC.  Do you have the machine
>in Fast mode?  If it is in Normal mode, it will be too slow to
>allow transfers faster than 9600 bps.  Check your control
>panel.  [ctrl][open apple][esc].

Sound to me like both of you guys are using non-hardware handshaking
cables to connect your IIgs' to other machines.  If you don't use
hardware handshaking cables, then you will definitely get errors at
higher transfer rates.  Even more errors if you are transferring files
to a slow drive such as a floppy.

Without hardware handshaking, the only way to get the other computer
to stop sending is to use software handshaking.  This is the XON/XOFF
that William mentioned.  This type of handshaking isn't as reliable as
hardware handshaking as the other computer won't stop sending until it
has received an XOFF character from the IIgs so you might have a
buffer overflow before the XOFF character gets there.  This is more
apparent at higher transfer rates.

A properly wired hardware handshaking cable is also dependent on the
communications program that you are using.  Fortunately, the most
popular communications programs all started using the same cable
pinout so if you are using ProTERM, Spectrum, ANSITerm or one of a
couple other programs, they will all be able to use the same hardware
handshaking cable.

Another problem you are probably running into is using non-optimized
code.  ZLink is definitely a decent program but being an 8 bit
program, it will almost certainly be slower than a 16 bit program and
I don't believe its transfer routines were ever optimized to run as
fast as they possibly could.  ProTERM, on the other hand, gives the 16
programs a run for their money and can even outperform them due to
GS/OS overheads and such slowing down the 16 bit programs.
AppleWorks' communications module is definitely not an optimized piece
of code and practically no one uses it for serious communications work
because it is too slow and only offers XModem or ASCII transfers.

Another thing to note, even on my 8 MHz IIgs, I have never been able
to obtain the full 57600 bps transfer rate between my PC and my IIgs.
I can only get between 30000 and 40000 bps even with the port set at
57600 bps.  This is do to lots of factors.  The point I'm making is
that if you can communicate with few to no errors with your port set
at 38400 bps you'll be doing fine as chances are, you'll never be able
to exceed that speed.

One final thing to note, you will also get faster transfers if you use
a transfer protocol that uses 1024 byte packets (or larger if you can
manage it) instead of XModem's 128 bytes packets as there is less
overhead.

However, as Mark mentioned, things are quite a bit faster if you use
AppleTalk.  If you are wanting to transfer stuff from a PC and don't
have the hardware and/or software to do AppleTalk, then you could use
a LANceGS card in a IIgs to connect to the PC and do FTP transfers
over a TCP/IP network.  :)

--
 Jeff Blakeney - Dean of the Apple II Unversity on A2Central.com