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 Forum index » Instruments and Equipment » General Discussion
So I just got a Tandy m100...
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opg



Joined: Mar 29, 2004
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PostPosted: Tue Oct 25, 2005 7:20 am    Post subject: So I just got a Tandy m100... Reply with quote  Mark this post and the followings unread

This thing is brilliant! 20 hours on 4 AA batteries and MS BASIC in a perfect sized case.

I brought home an Apple IIe last summer and have been blasting fat square waves through the cassette output into my mixer by looping the "POKE -16337,0" command. I've read about numerous programs that use machine code to create music, but I've been able to create a 2-octave chromatic scale just by changing the second address in the POKE command (i.e. -16337,12 and -16337,100.5), with the exception of the note "D," for some reason.

ANYWAY, back to the Tandy m100. This rockin' laptop does not have a simple 1/8" jack for the cassette drive like the Apple IIe, but rather another type of jack that uses a cable that switches it to a 1/8" cable. And when I took a look at that jack, guess what I saw - IT'S A DAMN MIDI JACK! I'm about 90% sure, but I was wondering if anyone knows about this?

I bought a Roland MS-1 off of eBay last week, and if it indeed has the same pin setup as a MIDI cable, I should be able to create a program in BASIC that could act as a sequencer for the Roland MS-1 or whatever other MIDI-enabled sampler I may use. I know the MS-1 has some sort of simple sequencer built in, but just the fact that I may be able to tweak this Tandy into a MIDI machine is awesome!
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mosc
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PostPosted: Tue Oct 25, 2005 8:21 am    Post subject: Reply with quote  Mark this post and the followings unread

I have one of those beasties in my attic somewhere. The plug is a DIN connector, the same as MIDI uses, but it's not MIDI. DIN connectors can be used for anything. MOOG used a three pin DIN for a power supply connector on the Etherwave Theremin. (Proves he wasn't a genius all the time).

http://www.cablestogo.com/resources/din.asp

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opg



Joined: Mar 29, 2004
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PostPosted: Tue Oct 25, 2005 9:01 am    Post subject: Reply with quote  Mark this post and the followings unread

Thanks for the link. I just found the pin settings for both a few minutes ago. Both a standard MIDI cable and the interfaces for the Cassette and Modem are the same 1 - 4 - 2 - 5 - 3, where 2 is GND. On the Tandy, Pin 4 is Receive and Pin 5 is Transmit.

I see this as a plus, but do you think it is possible to write a program - either in MS BASIC or machine code - to send data out from the Tandy to the sampler that the sampler could interpret as MIDI data?

I'll have to look at the MIDI commands first to see how much work might be involved. No problem if it doesn't, I just love these older machines and their cassette tape I/Os!
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opg



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PostPosted: Tue Oct 25, 2005 9:03 am    Post subject: Reply with quote  Mark this post and the followings unread

Oh, BTW - BIG MISTAKE earlier.

It's a Tandy 102.
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mosc
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PostPosted: Tue Oct 25, 2005 9:10 am    Post subject: Reply with quote  Mark this post and the followings unread

opg wrote:
I see this as a plus, but do you think it is possible to write a program - either in MS BASIC or machine code - to send data out from the Tandy to the sampler that the sampler could interpret as MIDI data?


Anything is possible.

Quote:
I just love these older machines and their cassette tape I/Os!


Shocked

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deknow



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PostPosted: Tue Oct 25, 2005 9:20 am    Post subject: Reply with quote  Mark this post and the followings unread

i know that some midi cables don't have all 5 wires connected, so you should check the cable pin by pin.

deknow
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opg



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PostPosted: Tue Oct 25, 2005 9:34 am    Post subject: Reply with quote  Mark this post and the followings unread

From what I've just read, a standard MIDI cable uses just pins 4, 2 (GND), and 5. That seems to sync up perfectly, assuming pin 4 is receive and pin 5 is transmit.

Also, a standard MIDI cable has a data rate of 31250 kilobits per second. I don't know if I have to worry about this or not yet.
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deknow



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PostPosted: Tue Oct 25, 2005 9:43 am    Post subject: Reply with quote  Mark this post and the followings unread

...there is no real ground connection on midi cables.

pin 2 is the shield (but should be connected to ground on only the source machine, not the recieving).

the midi spec uses an optoisolator on the input which is electrically connected to the source midi "out"...but the electrical signals (and ground) don't go any further into the recieving device than the midi port. this prevents (usually) midi from causing ground loop problems.

deknow
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ian-s



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PostPosted: Tue Oct 25, 2005 9:43 am    Post subject: Reply with quote  Mark this post and the followings unread

The 5 pin DIN was the standard for cassette a long time before midi.
The cassette output is likely to be FSK, where ones and zeros produce different frequency pulse tones. MIDI requires standard digital data at 31.25K(?). It may be possible to program a UART to this frequency and 1 start bit + 8 data bits + 1 stop bit. The only problem would then be bypassing the modulator and programming multi byte MIDI messages in BASIC without a serial queue Shocked .
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opg



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PostPosted: Tue Oct 25, 2005 10:25 am    Post subject: Reply with quote  Mark this post and the followings unread

I'm reading up on UART here: http://www.freebsd.org/doc/en_US.ISO8859-1/articles/serial-uart/index.html#UART

I forgot about the entire cassette=analog and MIDI=digital thing, Embarassed
but I'll still keep reading...

Worst case scenario, there's no MIDI fun, but I'll still be able to use the cassette output like I did with the Apple IIe.
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