JVC MSX MIDI Interface

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By o.geerdink

Hero (551)

o.geerdink's picture

19-11-2015, 10:21

I got it, but no software. The seller thought it was for Amstrad. The producer did make midi software for zx spectrum and amstrad which can be foud but not the msx version.

By Grauw

Ascended (8903)

Grauw's picture

19-11-2015, 14:28

Got a link to the Spectrum and Amstrad software? If the hardware is really the same it may help me figure out the chipset used. (I assume you don’t want to try to open yours up? Smile)

By o.geerdink

Hero (551)

o.geerdink's picture

19-11-2015, 18:51

http://www.zxspectrumreviews.co.uk/Search.aspx?pub=1261

Er is vrij veel te vinden, volgens mij heet de maker "Electro Music Research" en niet "Electro Musical Research" zoals op generation-msx staat.

Dit is hun oude adres:

Le Computer (EMR Sales Dept)
Main Road
Willows Green
Chelmsford
Essex
CM3 1QB

Tel Sales and Enquiries : 01245 362225
Fax : 01245 362048
Technical Helpline : 0860 382242 (4-6pm weekdays)

By o.geerdink

Hero (551)

o.geerdink's picture

19-11-2015, 18:52

Maybe the other system was BBC btw, I didn't find anything solid Sad

By Grauw

Ascended (8903)

Grauw's picture

12-05-2019, 01:19

http://mdfs.net/Info/Comp/BBC/MIDI/
http://mdfs.net/Info/Comp/BBC/MIDI/emr.gif

Looks like it’s based on the 6850 ACIA, like the Music Module.

By rderooy

Paladin (683)

rderooy's picture

12-05-2019, 10:13

Well since Philips did not actually make the NMS1205 Music Module, it was made by Richard Watts Computers Ltd and Music Sales Ltd. as printed on the PCB. Perhaps there was some connection between them and EMR. Or it is just coincidence :-)

By Grauw

Ascended (8903)

Grauw's picture

12-05-2019, 15:59

Grauw wrote:
  • Pins on the cartridge’s edge connector: /INT, /IORQ, /WR, A0-A2, A4-A7, D0-D7, GND, CLOCK, +5V, SW1, SW2. This confirms that it is I/O based. Also A3 is missing so it probably uses 8 I/O ports, and another 8 mirrored. /RD is missing but maybe it infers it from the absence of /WR?

Where have I seen that kind of mirroring before? Big smile

By Manuel

Ascended (16368)

Manuel's picture

11-06-2019, 21:39

Grauw, did you ever find out more about it? I just read the article in MSX Computing and now I'm more interested Smile

By Grauw

Ascended (8903)

Grauw's picture

13-06-2019, 21:56

Well knowing that it’s the 6850 ACIA and the I/O range it should be pretty easy to get it to work with a few attempts. But I haven’t been working on any MIDI project recently so I haven’t been looking into that. Could try to adjust the Philips MIDI driver in Synthesix to work with this guy.

By gflorez

Rookie (21)

gflorez's picture

31-03-2020, 14:43

It seems that almost all EMR Midi interfaces share the main box. At least the interfaces made for Z80 based computers, like the Spectrum, CPC and the MSX.

On the CPC the decoding of the port range is made on the connection box by a 74LS138B(all chips installed on the interface have the labels erased), and sent the decoded signal to the main box. F8FXh on the CPC, 0Xh on the MSX.

Then, another decoding is made on the big box. Port 0 is used to receive signals from the clock connector, optional, only used on old MIDI gear, port 2 Write is the Control register, while port 2 Read is the Status register. Port 3 is the Data I/O.

According to the MC6850 data sheet on page 8, a correct initialisation is to send 3 and 16h to the port 2, Control register.

03 means XXXXXX11b, resets the chip.

16h means 00010110:
-Bits 0 and 1, "10" means 2.000.000/64=31250 BAUDS.
-Bits 2 to 4, "101" means 8 bit word 1 stop bit.
-Bits 5 and 6, "00" means /RTS=low and interrupts disabled. "EMR MidiTrack Performer" CPC program uses "10" here, /RTS=high and interrupts disabled.
-Bit 7, "0" means Receive interrupts disabled, but the "EMR MidiTrack Performer" CPC program uses "1" when recording Midi. The EMR interfaces are provided of an /INT signal from the computer, but to use it correctly the computer system interrupt routine needs to be hooked.

The "EMR MidiTrack Performer" CPC program only weights 8KB(excluding 17KB of the static screen on a separate file), and I have it partially disassembled. I think it could be very easy to convert it to the MSX. The MSX screen I have seen looks almost the same as the CPC version, but with other colours.


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