trb@stag.UUCP ( Todd Burkey ) (01/24/88)
In article <1901@cadovax.UUCP> keithd@cadovax.UUCP (Keith Doyle) writes: > >Except for the minor detail that MIDI is not bidirectional. It's a one-way >link. But then you can do what the MIDI people do, and use one cable >for send, and one for receive. The Atari ST achieves a bidirectional >link (when using it for networking) presumably by diverging from MIDI spec. This is just a problem of semantics here. As in the Atari, most midi keyboards have both a midi in port and a midi out port. And some even have a midi through port. Most of the Amiga add-on MIDI ports support this. It really depends on how you think of the wiring in the cables... One nice thing is that by FOLLOWING the MIDI spec, Atari owners are able to use MIDI for networking. You just make a ring by going from the midi out of one machine to the midi in of another all the way around until you have completed the circle (just like musicians have had to do for years now hooking up their midi instruments to computers). It isn't the fastest net, but it is inexpensive and easy to set up (an ethernet connection is about $150 for the ST...but then you have to have something to hook up with.) It is plenty fast enough for networking 10 or so computers in a friendly(?) game of Midi-Maze. Speaking of Midi-Maze ( :-) )...has anyone heard if that is out yet for the Amiga. Considering how competitive and noisy it gets in my house when 8 of us ST owners get together for a shootout, I can imagine what it will be like when I invite 8 of my Amiga owning friends over...team play would be interesting. -Todd Burkey trb@stag.UUCP
dillon@CORY.BERKELEY.EDU (Matt Dillon) (01/27/88)
:One nice thing is that by FOLLOWING the MIDI spec, Atari owners are :able to use MIDI for networking. You just make a ring by going from :the midi out of one machine to the midi in of another all the way :around until you have completed the circle (just like musicians have :had to do for years now hooking up their midi instruments to :computers). It isn't the fastest net, but it is inexpensive and easy :to set up (an ethernet connection is about $150 for the ST...but then :you have to have something to hook up with.) It is plenty fast enough :for networking 10 or so computers in a friendly(?) game of Midi-Maze. Er, I don't see the advantage. Why not just connect the normal serial port Rx and Tx in a ring? Better, one or two chips and a connector will make you an O.C. (Open Collector) connection and you have ethernet-style rather than ring (which is costly to nodes when the nodes are microcomputers). -Matt
wtm@neoucom.UUCP (Bill Mayhew) (01/28/88)
You can get some really funky feedback effects when two synthesizers (or other MIDI devices) are connected in a ring fashion with each synth's OUT connected to the other's IN. Of course, each synth has to be receiving and transmitting on the same channel. Feedback occurs because the local CPU in each synth has to pick up the data look at it, and insert any of its own MIDI events in the data stream; a slight delay is generated as the data takes a trip though the CPU. The MIDI THROUGH port should have no delay, as by definition it is merely a repeater socket. The lesson here for musicans is that if you are driving several synthesizers from one MIDI out, it is best to connect them in parallel, so that a time delay isn't imparted to notes that should be coming out of several synths simultaneously. Note that the THROUGH port effectively connects them in parallel. The lesson for programmers is that is makes a good token ring approach (albeit slow in the case of MIDI 32.5 KBPS), and this has been neatly exploited in the ST's Midi Maze program. --Bill
karl@sugar.UUCP (Karl Lehenbauer) (02/15/88)
In article <318@stag.UUCP>, trb@stag.UUCP ( Todd Burkey ) writes: > One nice thing is that by FOLLOWING the MIDI spec, Atari... Note: The MIDI connectors, at least on the 520 ST, are *not* compliant with the International MIDI Association (IMA) MIDI specification. The MIDI 1.0 spec, as defined by the IMA, specifies that the three unused pins on the five-pin DIN connectors be left unconnected. The ST puts power on at least one of these pins. Granted, it can easily be hacked to be compliant, and since (apparently) no other manafacturer has deviated from the spec, it hasn't fried anyone's hardware (yet). Nonetheless, the ST does not comply with the spec. > ...Atari owners are > able to use MIDI for networking. You just make a ring by going from > the midi out of one machine to the midi in of another all the way > around until you have completed the circle (just like musicians have > had to do for years now hooking up their midi instruments to > computers). I thought pretty hard about using MIDI as a token ring back when the ST came out. The problem is that *all* the machines in the ring have to be up and running the network software or the net doesn't work. On commercial token ring implementations, such as Apollo's, there is a relay on each workstation's network board that causes the machine to be electrically disconnected from the net when the machine is down or when it's up but the network software isn't running. (Granted, there are pathological conditions that can still break a net) On a machine implemented the way the ST is; that is, a machine that needs to be rebooted a lot in the normal course of it's operation, this is fatal for anything but hoyybist get-togethers. -- ..!uunet!nuchat!sugar!karl, Unix BBS (713) 933-2440
trb@stag.UUCP ( Todd Burkey ) (02/18/88)
In article <1452@sugar.UUCP> karl@sugar.UUCP (Karl Lehenbauer) writes: >On commercial >token ring implementations, such as Apollo's, there is a relay on each >workstation's network board that causes the machine to be electrically >disconnected from the net when the machine is down or when it's up but >the network software isn't running. (Granted, there are pathological >conditions that can still break a net) We have around 300 Apollo's on two rings at work...it is really easy to break a net :-(. Remember also that that relay wasn't always on the Apollo boards. We got along fine during the early Apollo workstation years without such a switch. Then networks got so large we started demanding such a beast. >On a machine implemented the way >the ST is; that is, a machine that needs to be rebooted a lot in the >normal course of it's operation, this is fatal for anything but hoyybist >get-togethers. Fortunately it is mostly the hobbyists that spend all their time rebooting their computers. I've used ST's in a normal business environment (engineering and software development) for days on end with out seeing a crash. As a developer, however, I think I can safely say that neither the Amiga or the ST (I used to have both) could make it through a night of programming without resetting and maybe even rebooting a couple of times (my programming anyway, since I always seem to save up my goofups for when I am in in supervisor mode...) If properly implemented, I would imagine that a Midi Ring could even handle the occassional reboot without any glitches. Midi-Maze seems to handle this pretty well...you can remove a machine from the network without causing everyone to reboot, but obviously the net is down until the connection is re-established. I can envision a little heartbeat controlled bypass circuit that could be built for several dollars per machine, but it just wouldn't be worth the effort on small networks... -Todd Burkey trb@stag.UUCP
richard@gryphon.CTS.COM (Richard Sexton) (02/19/88)
In article <343@stag.UUCP> trb@stag.UUCP ( Todd Burkey ) writes: >In article <1452@sugar.UUCP> karl@sugar.UUCP (Karl Lehenbauer) writes: > >>On commercial >>token ring implementations, such as Apollo's, there is a relay on each >>workstation's network board that causes the machine to be electrically >>disconnected from the net when the machine is down or when it's up but >>the network software isn't running. (Granted, there are pathological >>conditions that can still break a net) > >We have around 300 Apollo's on two rings at work...it is really easy >to break a net :-(. Remember also that that relay wasn't always on the >Apollo boards. We got along fine during the early Apollo workstation >years without such a switch. Then networks got so large we started demanding >such a beast. 300 ? Gak, we had 15 and once a week we'd go crawling around the building trying to find the break. Boy I'm glad I use Z-boxes now... right -- "Each morning when I wake up to rise, I'm living in a dreamland" richard@gryphon.CTS.COM {ihnp4!scgvaxd!cadovax, rutgers!marque, codas!ddsw1} gryphon!richard