Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: nyu notesfiles V1.1 4/1/84; site rocksvax.UUCP Path: utzoo!linus!philabs!cmcl2!seismo!rochester!rocksvax!dave From: dave@rocksvax.UUCP Newsgroups: net.music.synth Subject: Re: rs232 midi interfaces Message-ID: <26500001@rocksvax.UUCP> Date: Wed, 20-Feb-85 11:35:00 EST Article-I.D.: rocksvax.26500001 Posted: Wed Feb 20 11:35:00 1985 Date-Received: Sun, 24-Feb-85 04:35:47 EST References: <870@bnl.UUCP> Lines: 29 Nf-ID: #R:bnl:-87000:rocksvax:26500001:000:1375 Nf-From: rocksvax!dave Feb 20 11:35:00 1985 /***** rocksvax:net.music.synth / ssc-vax!zadco / 1:10 am Feb 20, 1985*/ > In article zadco@ssc-vax.UUCP (Rick Fairfield) writes: > > >MIDI requires over 30000 bits/sec. RS232 usually runs at most 19200 baud so, > >as you can see, MIDI is a problem over RS232. > > zzzzadco >Well. I'm confused on this issue. I thought buad translated roughly to >bits/sec, so 9600 baud would be 9600 bits/sec. RS232 has nothing to do with baud rates or data formatting, it is an electrical specification. It says things about what signal belongs on what pin, how the many volts these signals are, what level of electrical isolation required, and as a final note when sending data, how long a cable you can use for typical clock frequencies (effectively baud rates). Typical asynchronous formats use 10 bauds to transmit 8 bits. (1 start bit, 8 data, 1 stop bit) Assuming that the thing is async, I believe it is, then, 30000/8= 3750 bytes/sec which would be sent at a rate of 37500 baud. Most of the UART chips require a 16x clock to synchronize the data to its internal shift register so the chip requires a 600Khz clock. Most old UARTS just make this. I believe this was the reason they picked that rate and the crystal for the oscillator is an off the shelf value. Dave arpa: Sewhuk.HENR@Xerox.ARPA uucp: {allegra,rochester,amd,sunybcs}!rocksvax!dave