Subject: Re: //gs LocalTalk Port From: dempson@actrix.gen.nz (David Empson) Date: Thu, Jul 23, 1998 918ÿÿ@ EDT Message-id: <1dbm7k1.1vc17qz5l3y12N@dempson.actrix.gen.nz> Nathan Mates wrote: > In article <359B4A56.3CF6B79D@netcomi.com>, Dan Bethe > wrote: > > >Oh, so if I did Appletalk between a //gs and a Linux pc, it would work > >at a maximum of 57600bps? But if I did Appletalk with a //gs and a //gs > >or Mac, then it would be at a happy 230kbps? > > No. Appletalk is ONLY at the 230kbps speed, asynchronous. No, LocalTalk is 230400 bps SYNCHRONOUS. > Modems (and all other normal serial transmissions, such as printers, null > modems and the like) are up to 57.6kbps, synchronous. No, they are ASYNCHRONOUS. Synchronous means clocked: LocalTalk uses Manchester coding, in which there are one or two transitions per bit cell, with the clock being recovered and kept in phase with each bit. Some synchronous communication methods use a separate clock signal. There is no per-character data overhead, though there is usually frame-level overhead and possibly inserted bits or bytes to handle data transparency. Asynchronous data is not clocked. The sending and receiving devices need to be set to communicate at the same data rate (or auto-detect it from receive data, in the case of modems). Characters have start and stop bits, and the start bit is used to determine where character boundaries are located. > The Appletalk card or an external device to go from Ethernet <-> > Appletalk LocalTalk (the physical layer and data link protocol), not AppleTalk (the entire protocol stack). > Well, ip-over-appletalk is specced out as a protocol, but Apple > couldn't be bothered to support such a thing. See my other post. It has been a standard feature in MacOS since Open Transport was released, and has been supported for a long time before that with add-on software. -- David Empson dempson@actrix.gen.nz Snail mail: P.O. Box 27-103, Wellington, New Zealand