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Author Topic: Enterprise MIDI hardware (Read 2933 times)

Offline Zozosoft

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Re: Enterprise MIDI hardware
« Reply #15 on: 2018.December.17. 14:37:01 »
István! You already looked inside the Scoretrack. Can you made a memory map of the 'a' Studio cartridge?

Offline Zozosoft

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Re: Enterprise MIDI hardware
« Reply #16 on: 2018.December.17. 15:01:05 »
Thanks! More easy to make schematic when know what do it is :-)

Online gflorez

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Re: Enterprise MIDI hardware
« Reply #17 on: 2018.December.17. 19:21:04 »
Cartridges also have the disadvantage that they do not support I/O ports. Memory mapped I/O is more problematic to emulate (unless it is somehow hacked into the existing SD card interface), and it would be slower to read in a modified version of midiplay, because paging needs to be saved, changed and restored in a high frequency IRQ handler. Assuming it is based on the 6850, input could be implemented better if the interface supported generating interrupts, otherwise the 6850 needs to be polled at a fixed high frequency, which does work, but uses more CPU time. With a VHDL implementation of the 6850, a minor optimization would be possible by making the data register return FFh when no new data byte is available.

I think like you, better an external expansion card. We have all necessary signals there. And bus expanders are cheap to build.

On the MSX approach they seem to connect the MC6850 /IRQ pin 7 to Z80 /INT, but then, who knows the origin of the interrupt?. I think that what is needed is to implement another read-only port for the interrupt status.

Offline pear

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Re: Enterprise MIDI hardware
« Reply #18 on: 2018.December.23. 10:12:14 »
Does anyone have a photo of the bottom side of the interface PCB ?

Offline Zozosoft

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Re: Enterprise MIDI hardware
« Reply #19 on: 2018.December.23. 11:49:39 »
Does anyone have a photo of the bottom side of the interface PCB ?
22407-0

Offline pear

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Re: Enterprise MIDI hardware
« Reply #20 on: 2018.December.23. 12:07:30 »
Thanks :)
Do you have a photo of the top side with removed ROM ?

Offline Zozosoft

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Re: Enterprise MIDI hardware
« Reply #21 on: 2018.December.23. 13:57:48 »
Do you have a photo of the top side with removed ROM ?
Not yet :oops:
This is my interface. It is have a additional hack, for simulating ROM from SRAM. (But not work properly, ROM contents always damaged...) My plan is restoring it to original version. I hope after Christmas will have some free time :oops:
22409-0

Offline pear

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Re: Enterprise MIDI hardware
« Reply #22 on: 2018.December.23. 14:35:20 »
Would it be possible to borrow this interface ?
I'm trying to recreate the scheme.
There are terribly many vias :(

Offline pear

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Re: Enterprise MIDI hardware
« Reply #23 on: 2018.December.24. 06:57:26 »
I will not read more from photos :(
I can guess, but it's easy to make a mistake.

Offline Zozosoft

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Re: Enterprise MIDI hardware
« Reply #24 on: 2018.December.24. 13:01:49 »
Nice! This is in Eagle? Can you send the file? I will add the remaining wires.

Offline pear

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Re: Enterprise MIDI hardware
« Reply #25 on: 2018.December.24. 14:26:42 »
It's DipTrace, up to 300 pins is free. https://diptrace.com/
DB9 in original interface is probably MIDI thru.

Offline Zozosoft

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Re: Enterprise MIDI hardware
« Reply #26 on: 2019.February.06. 15:29:41 »
More photos:

Offline Zozosoft

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Re: Enterprise MIDI hardware
« Reply #27 on: 2019.February.06. 15:30:32 »
SRAM hack removed:

Online gflorez

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Re: Enterprise MIDI hardware
« Reply #28 on: 2019.February.06. 17:00:14 »
Being a new project, changing the pagination(and the MIDI.Rom code) to segment 06, the two devices(Midi+SD reader) can live together on the same cartridge.

Offline Zozosoft

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Re: Enterprise MIDI hardware
« Reply #29 on: 2019.February.06. 18:44:42 »
Being a new project, changing the pagination(and the MIDI.Rom code) to segment 06, the two devices(Midi+SD reader) can live together on the same cartridge.
Better idea put to Bus side. (06h used by EXDOS in SD cartridge)