Path: utzoo!utgpu!water!watmath!clyde!att!pacbell!hoptoad!unisoft!bdt!david From: david@bdt.UUCP (David Beckemeyer) Newsgroups: comp.sys.atari.st Subject: Re: MIDI Networking Message-ID: <404@bdt.UUCP> Date: 18 Oct 88 00:00:53 GMT References: <3602@druhi.ATT.COM> <6424@batcomputer.tn.cornell.edu> <594@hudson.acc.virginia.edu> <3277@pt.cs.cmu.edu> <5080@saturn.ucsc.edu> <101488084314@js.UUCP> Reply-To: david@bdt.UUCP (David Beckemeyer) Followup-To: comp.sys.atari.st Organization: Beckemeyer Development Tools, Oakland, CA Lines: 34 I have done several consulting jobs where clients have requested MIDI networking. While I was able to achieve reasonable performance for a transaction network, where relatively little data is transferred, the performance of a Remote Call Procedure file system implementation was so slow as to make MIDI practically unusable for this purpose. For UUCP connections it would be as reasonable and as useful as any other 9600+ bps UUCP connection. We have developed a UUCP that runs under MT C-Shell, and many customers are using MIDI for local UUCP connections between STs. There are two problems with MIDI as a true LAN. First the raw rate of 34 Kbit is ten times slower than a floppy drive. Second the ST MIDI hardware cannot sustain continuous 34 Kbit/s transfer, so the data must be error corrected (especially if it's mounted as a read/write file system), giving you an effective data rate far below the 34 Kbit/s level. In real life, a point-to-point MIDI connection, after adding in the error detection protocol overhead and retransmissions due to lost MIDI interrupts (the MIDI interrupt priority is lower than other ST interrupts, so some get lost), gives you an effective data rate of only about 10 Kbps. You can get higher rates using the RS-232 at 19.2 Kbaud or, even better, using the syncronous mode of the ST serial port we have achieved rates comparable to a floppy disk. Another place to look is the bi-directional parrallel (printer) port on the ST. It is nearly as fast as a hard disk, but it is CPU intensive (no DMA), so it isn't too good for multiuser applications, but might work for a dedicated server. -- David Beckemeyer (david@bdt.UUCP) | "Lester Moore - Four slugs from a .44 Beckemeyer Development Tools | no Les, no more." 478 Santa Clara Ave. Oakland, CA 94610 | - Headstone at Boot Hill UUCP: {uunet,ucbvax}!unisoft!bdt!david | Tombstone, AZ