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Author Topic: Enterprise MIDI hardware (Read 3358 times)

Offline pear

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Re: Enterprise MIDI hardware
« Reply #45 on: 2019.March.10. 11:40:38 »
U1=LS133
U2=LS02
U3=LS00 (horizontal)
U4=LS00 (vertical)

In general, it's about logic at the gates.

1. Is U4 gate not used (pins 4,5,6) ?
2. What is the output U1 (pin 9) connected to ?
3. What are the pins 5 and 6 of the optocoupler connected to ?
    From the photos I get that pin 5 is connected to RxDATA (pin 2 ACIA) and to the U3 C gate (pin 9 and 10).
    If this is the case, where is the output of U3 C (pin 8 ) connected ?
4. The U2 A output (pin 1) is connected to CS0 and CS1 ACIA.
    My guess is that the inputs of the U2 A gate (pin 2 and 13) are A14 and A15, but I can not see these connections (you will find A14 on pin 11 U1 and A15 on pin 4 U1).
5. Finally, the biggest puzzle - U3 A (in 1,2, out 3), U3 B (in 4,5, out 6) and U3 D (in 12,13, out 11).
   The U3 A output seems to be connected to the CE ROM input, but it's kind of weird.
    I do not know where the pins 14 (Enable), 13 (R/W) and 5 (RTS) of ACIA are connected.

It's possible that in the end I would have guessed the right combination of connections (it's a bit like Sudoku ;) ), but it's easy to make a mistake.

The attachment contains the current state of the schematic.
« Last Edit: 2019.March.10. 12:03:33 by pear »

Online Zozosoft

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Re: Enterprise MIDI hardware
« Reply #46 on: 2019.March.11. 23:19:52 »
1. Is U4 gate not used (pins 4,5,6) ?
Yes.

Quote
2. What is the output U1 (pin 9) connected to ?
U2 pin 3
U3 pin 1

Quote
3. What are the pins 5 and 6 of the optocoupler connected to ?
pin 6 NC
Quote
   From the photos I get that pin 5 is connected to RxDATA (pin 2 ACIA) and to the U3 C gate (pin 9 and 10).
Yes.

Quote
   If this is the case, where is the output of U3 C (pin 8 ) connected ?
U2 pin 5,6

Quote
4. The U2 A output (pin 1) is connected to CS0 and CS1 ACIA.
    My guess is that the inputs of the U2 A gate (pin 2 and 13) are A14 and A15, but I can not see these connections
Pin 2 /CART
Pin 3 U1-9

Quote
5. Finally, the biggest puzzle - U3 A (in 1,2, out 3)
Pin 1 U1-9
Pin 2 A15
Pin 3 EPROM Pin 20

Quote
U3 B (in 4,5, out 6)
It looks not used.

Quote
and U3 D (in 12,13, out 11)
Pin 13 /WR
Pin 12 /RD
Pin 11 ACIA 14

Quote
I do not know where the pins 14 (Enable)
U3 Pin11

Quote
13 (R/W)
/WR

Quote
and 5 (RTS) of ACIA are connected.
It is not connected.
« Last Edit: 2019.March.12. 14:27:29 by szipucsu »

Offline pear

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Re: Enterprise MIDI hardware
« Reply #47 on: 2019.March.12. 05:45:45 »
Thank You Very Much :bow: :bow: :bow:

Offline pear

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Re: Enterprise MIDI hardware
« Reply #48 on: 2019.March.12. 17:40:19 »
U2 pin 5,6
Are you sure the pins 5 and 6 are connected together ? Can not see such a connection in the pictures.

And the last question.
MIDI uses pins 4 and 5 in the DIN 5 connector.
Which colors in MIDI IN and MIDI OUT are connected to which pins ?
I specifically marked them separately because it seems to me that in each of the connectors the red and green wire leads to another pin.

In addition, the rest of the connections look promising.
I don't see any not covered paths in the pictures.
« Last Edit: 2019.March.12. 17:45:10 by pear »

Offline pear

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Re: Enterprise MIDI hardware
« Reply #49 on: 2019.March.12. 19:19:40 »
However, I found one unconnected path.
Probably one end lead to a pull-up resistor.
Where's the other end ?

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Re: Enterprise MIDI hardware
« Reply #50 on: 2019.March.12. 22:17:21 »
Are you sure the pins 5 and 6 are connected together ? Can not see such a connection in the pictures.
Yes. There is it :-)
23017-0

Probably one end lead to a pull-up resistor.
Yes.


Quote
MIDI uses pins 4 and 5 in the DIN 5 connector.
Which colors in MIDI IN and MIDI OUT are connected to which pins ?
IN:
red 5
green 4

OUT:
red 4
green 5

Offline pear

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Re: Enterprise MIDI hardware
« Reply #51 on: 2019.March.13. 07:56:39 »
Thanks :)

Probably one end lead to a pull-up resistor.
Where's the other end ?
Yes.
OK, fine, but the second end ?

Online Zozosoft

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Re: Enterprise MIDI hardware
« Reply #52 on: 2019.March.13. 09:03:46 »
OK, fine, but the second end ?
U2 pin 5,6 - U3 pin 8

Offline pear

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Re: Enterprise MIDI hardware
« Reply #53 on: 2019.March.13. 10:24:20 »
Hm, I wonder why ?
These are not open collector gates (U3).

Offline pear

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Re: Enterprise MIDI hardware
« Reply #54 on: 2019.March.13. 15:51:55 »
Final, reverse engineering schematic.
Can you check if it is correct ?

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Re: Enterprise MIDI hardware
« Reply #55 on: 2019.March.13. 16:21:50 »
Nice! :smt038
The J2 how numbered?
And also the resistors/capacitors?

Online gflorez

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Re: Enterprise MIDI hardware
« Reply #56 on: 2019.March.13. 17:41:33 »
I think  that J2 must be numbered following the Enterprise EDGE numbering convention, B component/upper side, A solder/down side, and the numbering, looking in front of the connector, pins starting from left to right.

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Re: Enterprise MIDI hardware
« Reply #57 on: 2019.March.13. 17:46:55 »
Here you are.
Connector J2 looks like the contacts for the DB9 socket.

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Re: Enterprise MIDI hardware
« Reply #58 on: 2019.March.13. 18:10:35 »
Ah, to directly solder a DB9. A good solution, much better than the two hanging DINs.

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Re: Enterprise MIDI hardware
« Reply #59 on: 2019.March.13. 18:13:50 »
That was on the original PCB.
On the connector there are signals for the third MIDI THRU socket and an IRQ signal from the ACIA system.