ragge@nada.kth.se (Ragnar Sundblad) (10/06/88)
Is it possible to do synchronous communication with the Serial Driver? I have understood that I can connect a clock to the HSKI-pin, but then? How do I tell the driver that it should use an external clock? How do I tell it to be synch.? How do I set the idle patterns etc? Any help greatly appreciated! /ragge@nada.kth.se
han@Apple.COM (Byron Han, Architect) (10/09/88)
In article <590@draken.nada.kth.se> ragge@nada.kth.se (Ragnar Sundblad) writes: >Is it possible to do synchronous communication with the Serial Driver? Theoretically yes. However, in reality, there are so many things that turn off interrupts (e.g. the Sony floppy driver, AppleTalk drivers, etc.) which make life a living ... well you get the message. You need to directly bang on the SCC to do synchronous communications through the serial ports. This is also a nono since the SCC may not always be accessible. Sorry for the bad news. ------------------------------------------------------------------------------ Byron Han, Communications Architect TANSTAAFL - You Get What You Pay For. Apple Computer, Inc. ------------------------------------- 20525 Mariani Ave, MS27Y Internet: han@apple.COM Cupertino, CA 95014 UUCP:{sun,voder,nsc,decwrl}!apple!han -------------------------------------- GENIE: BYRONHAN ATTnet: 408-973-6450 Applelink: HAN1 CompuServe: 72167,1664 ------------------------------------------------------------------------------
paul@unisoft.UUCP (n) (10/10/88)
In article <590@draken.nada.kth.se> ragge@nada.kth.se (Ragnar Sundblad) writes: >Is it possible to do synchronous communication with the Serial Driver? >I have understood that I can connect a clock to the HSKI-pin, but then? >How do I tell the driver that it should use an external clock? >How do I tell it to be synch.? >How do I set the idle patterns etc? You have to write your own device driver. To do this you need a data sheet for the Zilog 8530. This will tell you all this information. Look at Inside Mac IV/V for information about how the chips are wired into the Mac. Warning: because of the framing etc requirements for synchronous communications be carefull about writing code that will be used in environments that turn off interrupts for more than the time it takes to read 3 characters from the serial port (ie 3ms at 9600 baud - the chip has a 3 byte input buffer, actually allow some extra time for overhead say 2.5mS). This effectively rules out operation concurrently with the floppies or appletalk (which has hooks for the serial driver but not for any synchronous operation). Paul Campbell -- Paul Campbell, UniSoft Corp. 6121 Hollis, Emeryville, Ca E-mail: ..!{ucbvax,hoptoad}!unisoft!paul Nothing here represents the opinions of UniSoft or its employees (except me) "Nuclear war doesn't prove who's Right, just who's Left" (ABC news 10/13/87)