Re: Network for the GS?

[Matthew Carlson <carlson@rahul.net>]

Okay so your telling me if I hooked up my IIGS to an appletalk server I 
am going to get a theoretical transfer rate of 230.4kbps or 28.8kBps.
Very nice.

Now the question is how do I get it to boot off the network if I don't 
have a mac file server but, an ibm-pc one.


David Empson (dempson@atlantis.actrix.gen.nz) wrote:
: In article <4mefjt$r12@samba.rahul.net>,
: Matthew Carlson  <carlson@rahul.net> wrote:
: > David Empson (dempson@atlantis.actrix.gen.nz) wrote:
: > :
: > : [LocalTalk is] 230.4k synchronous, so only 8 bits are sent for
: > : each character and the theoretical maximum transfer rate is 28800
: > : bytes per second (the equivalent of an asynchronous serial link at
: > : 288k bps).  The bandwidth is limited by packet and protocol overheads,
: > : other network traffic, reaction time of the file server, reaction time
: > : of the workstation, etc.
: > 
: > Wait a minute here: 230.4k synchronous?!!!!!!
: > 
: > Appletalk on a Mac may be that but, on a IIGS non-accelerated?

: LocalTalk is the same on all machines - how else could a IIgs and Mac
: talk to each other?

: > Let us think about this, a 2.8mhz machine (2.5 or so with the ram refreshing)
: > that is able to transfer 1 byte in two cycles.?? 

: 230400 BITS per second, not BYTES per second.  A maximum of 28800 BYTES
: per second, as I said in the earlier article.

: LocalTalk is packet-based.  The receiving computer is interrupted for
: the first byte, and has to be able to respond within 100 microseconds,
: or it will lose the byte (the Z8530 has a three-byte receive buffer).
: The interrupt handler then remains active while receiving the whole
: packet, which can take up to 25 milliseconds (something like 580
: bytes).

: This is obviously going to cause problems with serial comms on the
: other port - 25 milliseconds is enough time for 50 bytes to be
: received at 19200 bps.  As long as your comms program uses the
: standard IIgs serial firmware, it shouldn't lose anything, because the
: AppleTalk firmware polls the other port while it is receiving a packet.

: If the comms program has its own interrupt handler, then data
: received at the same time as an AppleTalk packet will be lost.

: -- 
: David Empson
: dempson@actrix.gen.nz
: Snail mail: P.O. Box 27-103, Wellington, New Zealand