Re: //gs LocalTalk Port

[Charles Stephens <devnull@dobbs.eng.sun.com>]

>>>>> "NM" == Nathan Mates <nathan@visi.com> writes:

 NM> In article <359B4846.2F35573C@qut.edu.au>,
 NM> Willie Yeo  <w.yeo@qut.edu.au> wrote:
 >> I thought that the GS serial ports can handle up to 57,600 bps
 >> (57.6 kiloBITS per second) tops. And to achieve 230 kiloBITS per
 >> second you need to have a modified Apple Super Serial Card ?

 NM> For regular modem transmissions, then the 57600 bps speed
 NM> applies. Appletalk is done via a less-standard mode (asychronous
 NM> vs synchronous) not 'spoken' by the standard 16550[A] serial
 NM> chips found on non-Apple boxen. Same kind of quirk as the MFM vs
 NM> GCR floppy disk I/O, etc that prevents compatability by using
 NM> unusual combos of less-standard chips.

Just to clarify:

Standard modem-speak is async as well as LocalTalk.  However,
LocalTalk works completely different from EIA-232 (aka RS-232): it
somewhat resembles Ethernet (common carrier, collision detection,
etc.).  The IIgs can do this because of the Zilog SIO, which is highly
programmable.

The SSC has only a dumb UART, so no luck with AppleTalk.

If you want to learn more about LocalTalk and AppleTalk in general,
get "Inside AppleTalk, 2nd Ed.".  Good book.

cfs
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