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Midimate


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#1 atari8warez OFFLINE  

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Posted Wed Oct 10, 2007 1:38 PM

Ok here's a photo showing the guts of the Midimate Midi interface for 8 bit Ataris. Can anyone identify the IC's on this board. Apparently chip id's were erased during manufacturing for copyright reasons.

Added the solder-side photo of the board..

Attached Thumbnails

  • MidiMate__2_.JPG
  • MidiMate__3_.JPG

Edited by atari8warez, Thu Oct 11, 2007 9:14 AM.


#2 Mathy OFFLINE  

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Posted Wed Oct 10, 2007 3:14 PM

Hello Atari8warez

Wet your finger with a bit of spit and rub it over the black part of the chips. That's often enough to make the print more readable. But only for a long as the print stays wet.

Greetings

Mathy

#3 warerat OFFLINE  

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Posted Wed Oct 10, 2007 3:35 PM

Ok here's a photo showing the guts of the Midimate Midi interface for 8 bit Ataris. Can anyone identify the IC's on this board. Apparently chip id's were erased during manufacturing for copyright reasons.


U4 is obviously an opto-coupler. U2 and the IC on the left look like they're TTLs.

#4 atarifan49 OFFLINE  

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Posted Wed Oct 10, 2007 8:12 PM

Well the center 14 pin chip is a 74LS04 - inverter gate chip. I see that the upper right chip is a LM741 op-amp. The 741 is the most common, basic operational amplifier used for general purpose. I can't make ID and on the other chips without seeing more of the circuit connections.

The other small chip could be a audio amplifier, another op-amp, or a opto-isolator. I've seen a midi-adapter for the Jaguar use opto-isolator chip for circuit isolation.

Regards,
Glenn

#5 ndary OFFLINE  

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Posted Thu Oct 11, 2007 12:34 AM

Well the center 14 pin chip is a 74LS04 - inverter gate chip. I see that the upper right chip is a LM741 op-amp. The 741 is the most common, basic operational amplifier used for general purpose. I can't make ID and on the other chips without seeing more of the circuit connections.

The other small chip could be a audio amplifier, another op-amp, or a opto-isolator. I've seen a midi-adapter for the Jaguar use opto-isolator chip for circuit isolation.

Regards,
Glenn



Here is another picture of the Midimate board... anyone care to make a schematics out of it?

midi_board.jpg
ndary

#6 krupkaj OFFLINE  

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Posted Thu Oct 11, 2007 8:21 AM

The second side is neccessary for making the scheme and unfortunately you cannot see the traces under chips. So it is not possible to make scheme from photos.

BTW did somebody test the MidiMaze in network? We tried it with simple midi interface, but it did not work, so I think the MidiMate is neccessary. I would love to play MidiMaze in more people :) So if there is scheme we can make "new batch"...

Edited by krupkaj, Thu Oct 11, 2007 8:25 AM.


#7 atari8warez OFFLINE  

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Posted Thu Oct 11, 2007 9:01 AM

Hello Atari8warez

Wet your finger with a bit of spit and rub it over the black part of the chips. That's often enough to make the print more readable. But only for a long as the print stays wet.

Greetings

Mathy


Already tried that no luck :)

#8 atari8warez OFFLINE  

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Posted Thu Oct 11, 2007 9:19 AM

Well the center 14 pin chip is a 74LS04 - inverter gate chip. I see that the upper right chip is a LM741 op-amp. The 741 is the most common, basic operational amplifier used for general purpose. I can't make ID and on the other chips without seeing more of the circuit connections.

The other small chip could be a audio amplifier, another op-amp, or a opto-isolator. I've seen a midi-adapter for the Jaguar use opto-isolator chip for circuit isolation.

Regards,
Glenn



Here is another picture of the Midimate board... anyone care to make a schematics out of it?

midi_board.jpg
ndary


Hmm, looks like it's the same version (MM 1.0) as mine with labels intact. What were they thinking when they erased some and not others I wonder. Looking more carefuly, I see a US stamp on mine under the set of resistors on the lower left hand corner of the board, or is it U5... Guess it is...

Edited by atari8warez, Thu Oct 11, 2007 9:23 AM.


#9 Beetle OFFLINE  

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Posted Thu Oct 11, 2007 3:00 PM

I have to agree with Jan, we need some of these for MidiMaze network gaming. I remember
reading somewhere, the XL/XE Version could be networked with the ST version of Midimaze
(in case you use a Midimate Interface). The ingame drones ruin the gameplay :-(

#10 krupkaj OFFLINE  

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Posted Thu Oct 11, 2007 4:38 PM

What I know it is possible to connect whole network of 16 machines, ST, Amiga, 8bit together.

What are the other 2 connectors. I know there are 2 DIN with 5 pins, but what are the others? What thay are good for?

#11 atari8warez OFFLINE  

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Posted Thu Oct 11, 2007 6:07 PM

What I know it is possible to connect whole network of 16 machines, ST, Amiga, 8bit together.

What are the other 2 connectors. I know there are 2 DIN with 5 pins, but what are the others? What thay are good for?


They're for synching with a tape recorder, any musicians here by the way?

Edited by atari8warez, Thu Oct 11, 2007 6:11 PM.


#12 atari8warez OFFLINE  

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Posted Thu Oct 11, 2007 6:09 PM

What I know it is possible to connect whole network of 16 machines, ST, Amiga, 8bit together.

What are the other 2 connectors. I know there are 2 DIN with 5 pins, but what are the others? What thay are good for?


They're for synching with a tape recorder, any musicians here by the way?


Please somebody tell me, how do I delete a message I posted here. My fingers seem to be faster than my browser at times. Although on a second tought, maybe it's good to get that "two joystick" rating of mine bumped-up to the next level quickly :D

Edited by atari8warez, Thu Oct 11, 2007 6:18 PM.


#13 krupkaj OFFLINE  

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Posted Thu May 15, 2008 5:56 PM

I am trying to make a schematics from the photos. It looks not so bad. But I still miss some traces which are under chips. Can you check with multimeter where the missing traces go?
The colored traces are already in the scheme but we have to check if they are right. And then redraw the scheme. I know it looks little bit weird at the moment :)
midimate_eagle.png
midimate_traces.jpg

Edited by krupkaj, Thu May 15, 2008 6:03 PM.


#14 Mathy OFFLINE  

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Posted Fri May 16, 2008 8:18 AM

Hello Jan

Will we be seeing more of this at the Fujiama 2008?

Greetings

Mathy

#15 krupkaj OFFLINE  

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Posted Sun May 18, 2008 11:34 AM

OK, here is better scheme. I was able to make nearly all connection under the chips. But I am missing one. There is oscillator from 7404 (gates E and F). It is necessary to connect it to gate A from 7404. But I am not sure how. Please can anybody who photographed the interface check this connection with multimeter? Also please check the traces under the chips. I think I know how they are connected, but I would like to be sure. They are painted with white dotted line on the photos.

midimate.sch.png

midimate_traces.jpg

#16 krupkaj OFFLINE  

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Posted Sun May 18, 2008 11:36 AM

Will we be seeing more of this at the Fujiama 2008?


It depends somebody help me with the rest. Unfortunately I have not this device. So it is not easy task to make scheme only from pictures.

#17 Mathy OFFLINE  

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Posted Sun May 18, 2008 11:51 AM

Hello Jan

But you will be there?

BTW some MIDI interfaces have three port (IN, OUT and THRU), looks like this one only has two (IN and OUT). How hard would it be, to add a THRU port?

I see in an article I wrote myself that the MIDI Mate interface only has one SIO connector. Maybe you could make the board so that those who want a second SIO connector can solder it in themselves?

Greetings

Mathy

Edited by Mathy, Sun May 18, 2008 11:58 AM.


#18 puppetmark OFFLINE  

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Posted Sun May 18, 2008 12:34 PM

U4 is obviously an opto-coupler. U2 and the IC on the left look like they're TTLs.


Yep its a Sharp PV900. The PV900 is hard to find but it can be substituted by a 6N138. You can get the 6N138 from Jameco (and many other places) for under a dollar each. I have only found 1 place to get the PV900 and they are $5.00 each. Anyway, I found this circuit which is actually for a PC joystick port but it shows the differenced between the two optocouplers. IMHO I think it would be wise to use the 6N138 in the "cloned MIDIMate"

Midi_Interface.jpg

Edited by puppetmark, Sun May 18, 2008 12:46 PM.


#19 pepax OFFLINE  

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Posted Mon May 19, 2008 1:53 AM

Yep its a Sharp PV900. The PV900 is hard to find but it can be substituted by a 6N138. You can get the 6N138 from Jameco (and many other places) for under a dollar each. I have only found 1 place to get the PV900 and they are $5.00 each.

The Sharp PC900V can be easily bought here (CZ).

If there's any MIDIMATE owner reading this thread, could you please let us know? We need help with tracing the last few connections hidden under some ICs....

#20 raster/c.p.u. OFFLINE  

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Posted Wed May 28, 2008 11:44 PM

BTW some MIDI interfaces have three port (IN, OUT and THRU), looks like this one only has two (IN and OUT). How hard would it be, to add a THRU port?

THRU port is sending signals coming from IN port olny. It has sense for musical instruments if you need control more musical instruments from one master computer. So, this port is useless for Atari midi interface, because Atari is the master.

#21 Mathy OFFLINE  

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Posted Thu May 29, 2008 10:46 AM

Hello Raster

THRU port is sending signals coming from IN port olny. It has sense for musical instruments if you need control more musical instruments from one master computer. So, this port is useless for Atari midi interface, because Atari is the master.

But wouldn't it be nice to have a THRU port for networking?

Greetings

Mathy

#22 raster/c.p.u. OFFLINE  

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Posted Fri May 30, 2008 12:18 AM

Hello Raster
But wouldn't it be nice to have a THRU port for networking?
Greetings
Mathy

Hello Mathy.
For "MIDI networking" (Midimate) there is circle network topology.
So, comp1_midiOUT -> comp2_midiIN/comp2_midiOUT -> ... > compN_midiIN/compN_midiOUT -> comp1_midiIN
THRU port is redundant in this structure.

#23 UNIXcoffee928 OFFLINE  

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Posted Fri May 30, 2008 6:11 AM

(raster/c.p.u. @ Thu May 29, 2008 7:44 AM)]
THRU port is sending signals coming from IN port olny. It has sense for musical instruments if you need control more musical instruments from one master computer. So, this port is useless for Atari midi interface, because Atari is the master.



Hello Raster
But wouldn't it be nice to have a THRU port for networking?
Greetings
Mathy

Hello Mathy.
For "MIDI networking" (Midimate) there is circle network topology.
So, comp1_midiOUT -> comp2_midiIN/comp2_midiOUT -> ... > compN_midiIN/compN_midiOUT -> comp1_midiIN
THRU port is redundant in this structure.


Yeah, sure... So you are saying that apples are blue & orange trees grow in Alaska.

Just so the other readers are aware, MIDI THRU is re-transmission of the exact copy of the data coming into MIDI IN. MIDI OUT will ONLY transmit data originating on the device in question (Some modern equipment will allow you to configure OUT as THRU, but it is fairly rare, and certainly wouldn't apply to the MIDIMATE, considering it's vintage).

MIDI networks are Star Topologies with provisions for daisy chaining 16 discrete channels on each asynchronous serial interface, on a port by port basis. So, the more MIDI interfaces (known as ports) that you have, the more 16 node networks that you have.

Just so that there is no confusion, Interface Ports are not IN/OUT/THRU ports, but rather the MIDI interface itself. There are 16 possible IN/OUT/THRU ports per Interface port. When using a computer, add more sound cards, get more interface ports with another 16 channels per port. If a device is cool enough, but has a very limited midi spec, give it it's own interface port, and you're good to go.

Any MIDI device without a THRU port is a headache waiting to happen.

Read the fine manual for the MIDI spec here:
http://www.gweep.net...l/midispec.html

Mathy could probably add that interface in a weekend himself. Anyone who has thoroughly read his page can easily zen out that he's a very talented engineer. Do take his advice, he knows what he's talking about.

= )

Edited by UNIXcoffee928, Fri May 30, 2008 6:12 AM.


#24 Mathy OFFLINE  

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Posted Fri May 30, 2008 6:20 AM

Hello UNICcoffee928

Mathy could probably add that interface in a weekend himself. Anyone who has thoroughly read his page can easily zen out that he's a very talented engineer. Do take his advice, he knows what he's talking about.


You are forgetting that the information I have on my internetsite mostly comes from other people. I'm not an electronics engineer, although I do know which side of a soldering iron I should hold.

But Mathy has had a MIDI-interface on his "I want one" list for ages. Unfortunately, Mathy doesn't play ANY instruments and decoding notes takes a while. But Mathy also wants a network interface that's easier to use then the MultiLink interface. And more versatile.

Greetings

Mathy

#25 UNIXcoffee928 OFFLINE  

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Posted Fri May 30, 2008 6:38 AM

What I know it is possible to connect whole network of 16 machines, ST, Amiga, 8bit together.

What are the other 2 connectors. I know there are 2 DIN with 5 pins, but what are the others? What thay are good for?


They're for syncing with a tape recorder, any musicians here by the way?


Yes, I play a number of instruments, & do engineering & production work.

Anyone have a manual to check what the ports are named?

If it is a SYNC port, then that's awesome! Not only can you sync it to tape recorders, but, more importantly, you can use it to trigger vintage synths, sequencers, & drum machines. Things like the arpeggiator in the Roland Jupiter 8 & the synchronization features of the Roland TR-808 & TB-303... hundreds of very desirable pre-MIDI analog synthesis devices used that spec. The other port may be for Voltage Controlled triggering, which is analogous to MIDI NOTE ON/OFF messages in pre-MIDI analog synths.

The Roland TR-707 has SYNC & MIDI, as it was a bridge between the eras. I think the TR-909 has that setup as well. The MIDIMATE would be a very valuable tool for owners of exotic antique synths. If you do replicate it, someone should send a review of it to a Synth-oriented music magazine.

Best of Luck with the project!




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