Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!bbn!apple!han From: han@Apple.COM (Byron Han, wyl E. coyote ) Newsgroups: comp.sys.mac.programmer Subject: Re: How fast can a MAC-SE drive a serial line? Keywords: serial, fast Message-ID: <28021@apple.Apple.COM> Date: 29 Mar 89 08:03:56 GMT References: <13655@jumbo.dec.com> Organization: Apple R&D - Networking & Communications Lines: 34 In article <13655@jumbo.dec.com> murray@jumbo.dec.com (Hal Murray) writes: >AppleTalk runs at 256K bits/second. I was expecting the vanilla serial >driver to be able to go as fast. "How fast could a woodchuck chuck wood if a woodchuck could chuck wood." I have a copy of the Macintosh (R) Family Hardware Reference. Chapter 12 has a section on the SCC (serial communications controller). AppleTalk can operate at 256KBits/second because it is not interrupt driven and when the AppleTalk driver is running, it has complete control over the Macintosh. Serial drivers are limited to a theoretical limit of 500kbaud with external clocking and the serial driver having complete uninterrupted control of the Macintosh. Nominally, you can probably get 57.6Kbaud with the standard serial driver The Hardware Family Reference is an Addison Wesley book and contains lots of interesting tidbits of information. Hope this helps. +-----------------------------------------------------------------------------+ | Disclaimer: Apple has no connection with my postings. | +-----------------------------------------------------------------------------+ Byron Han, Communications Architect Cereal, anyone? :-) A1! Apple Computer, Inc. ------------------------------------- 20525 Mariani Ave, MS27Y Internet: han@apple.COM Cupertino, CA 95014 UUCP:{sun,voder,nsc,decwrl}!apple!han -------------------------------------- GENIE: BYRONHAN ATTnet: 408-974-6450 Applelink: HAN1 CompuServe: 72167,1664 ------------------------------------------------------------------------------