Path: utzoo!utgpu!watmath!att!dptg!rutgers!aramis.rutgers.edu!athos.rutgers.edu!rbthomas From: rbthomas@athos.rutgers.edu (Rick Thomas) Newsgroups: comp.os.minix Subject: Re: problems bringing up Protected Mode Minix Keywords: rs232 -- printer driver Message-ID: Date: 1 Aug 89 05:04:24 GMT References: Organization: Rutgers Univ., New Brunswick, N.J. Lines: 37 So, after I got a protected mode kernel with the Bruce's TTY driver made, I went to test it out on my genuine IBM PC/AT (Old slow model -- 6MHz clock) with my Multitech V.32 9600 bps modem. After all, Bruce claimed that it worked on a 4.77MHz XT at 19.2Kbps. An AT should be at least as fast as that! (On the other hand, he did mention that access to the Extended memory RAM disk might keep interrupts locked for more than one character time on this configuration. So I was curious.) The results are mixed. It's seems to be OK for reading netnews and using vi for editing on the remote system, but bulk data transfer to disks (RAM or Hard) has problems with dropped characters (less with output to the RAM disk, more with output to the Hard disk.) Running kermit in protocol mode to download from a SUN to Minix with the receiving file on Hard disk using 1000 character packets gets frequent garbled packets and retransmissions. The garbles seem to to be associated with the moments when "update" wakes up and causes writes to the disk. Putting the output file on the RAM disk did not have any problems with garbles. On the other hand, turning on kermit's "session logging" to just grab everything that comes over the serial port and log it to RAM disk resulted in dropping large chunks of data. It appears that something is going on that is not fast enough to keep up with 9600bps without pauses. (I didn't try logging to Hard disk.) (??) All that message passing may be slowing things down (??). The next thing to try is enabling hardware (CTS/RTS) flow control. Rick -- Rick Thomas uucp: {ames, att, harvard}!rutgers!jove.rutgers.edu!rbthomas internet: rbthomas@JOVE.RUTGERS.EDU bitnet: rbthomas@zodiac.bitnet Phone: (201) 932-4301