Hack an Ancient MSI Music Chip?

I have this pc board out of a keyboard made by Think! Software. I dont' have any cables or information on it. I want to use the MIDI keyboard it attaches to, so need to hook up power to the pc board. Couldn't find pinouts anywhere for the main chip. You can see it here:

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Reply to
Zephinilium
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If all you want to do is power it up, find the power jack (J1, lower left?) and use the polarized caps (C1, C17) to trace back and figure out which pin is positive and which is ground. Voltage will be maybe

70% of the cap rated voltage. You likely have a wallwart in your junkbox that will work.

Shot-in-the-dark; Kennerly-Spratling (read the board) currently does plastic injection molding but apparently they used to make boards. Ask them if they archive stuff from back then!

Mark L. Fergerson

Reply to
alien8752

J1 is actually for the foot pedal. From what I read somewhere online (if I remember right), the PC interface (center connector P2) is how it gets its power.

Looks like C1 is a polarized cap. Maybe that will help. Thanks.

Yes I noticed also that Kennerly-Spratling does injection molding, so I assumed they would not be a source of information, but I could write to them as you suggest. Couldn't hurt.

ECP

Reply to
Zephinilium

That is an Intel 80C51 microcontroller. a quick Google for "80C51 datasheet" finds one from Philips, that indicates Vcc (+5V) is on pin

40, and ground is on pin 20.
--
Peter Bennett, VE7CEI  
peterbb4 (at) interchange.ubc.ca  
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Reply to
Peter Bennett

Very good. That should help greatly.

BTW, the "J1" connector on the left in the photo is for a foot switch, not a power connector. I think I read somewhere that it gets power from the computer connection (P2).

Here are the ports:

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-ECP

Reply to
Zephinilium

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As Peter mentioned, it is an 8051. Circa 1995, it almost certainly will be the 5-volt variety.

  • 5Vdc on Pin 40, ground on pin-20. There are a great many 8051 varieties, but all the 40-pin DIP packages pretty much pin out the same. I've never seen one that wasn't, and I recognize the crystal & caps on pins 18 & 19, right where you would expect them.

The MIDI ports (if it connects to a PC), will have the standard game port pin assignments. Google the pinout for a joystick / game controller on any IBM-PC clone or multi-I/O card. That should also give you a good confirmation that you have the right

5-volt bus, and grounds identified.

-mpm

Reply to
mpm

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Yup, here it is:

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And here (more MIDI emphasis):
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My goal is to use the MIDI port and use a MIDI/USB adapter I have and connect to a Mac via the USB port. So looks like I'll be trying to simply connect +5 volts and GND to Pin

1 & Pin 8 & 9 on the DA-15 and see what happens when I hook up the MIDI cable. Hopefully the chip is pre-programmed to send MIDI and doesn't require connection to a computer.
Reply to
Zephinilium

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Woops, Pin 1 is also 5 V. The outer connector is actually what connects to the chip's GND and the ground plane area on the board.

Reply to
Zephinilium

You want to use this to make a USB to MIDI adapter?

eBay USB MIDI adapter

Cable with a tiny box/lump in the middle. Some are as low as $ 2 with $ 4 shipping! I see auctions for 2.75 with free shipping.

It looks like somebody imported a lot of these and got stuck with a glut of them.

Notice that it works with name brand MIDI software.

USB to MIDI keyboard Interface Converter Cable

Specification:

Simply connect the USB cable into your computer,and your MIDI interface connection is completed. It is easy to turn your PC into a music studio. Starting by connecting a music keyboard to your computer with the supplied USB MIDI cable. HOT- seappable,you can connect and disconnect whenever you want,even while the computer is turned on. Draws its power from the computer's USB port,no AC adaptor needed. Supports Windows XP,Vista and Mac OS X operating systems.

Latest Version with a built-in driver. USB powered and Class Compliant for true plug & play.Just connect to a computer USB socket for automatic installation of driver.

1 in + 1 out MIDI interface. 16 MIDI input channels & 16 MIDI output channels. LED's indicate power in,MIDI in signal and MIDI out signal. Supports Windows XP/Vista and Mac OS X operating systems. Cable length: 2m.

Instructions for use: Please follow these steps Connect the cable marked 'IN' to the MIDI 'OUT' socket of a MIDI keyboard (or MIDI device). Connect the cable marked 'OUT' to the MIDI 'IN' socket of a MIDI keyboard (or MIDI device). Plug the USB cable into any free USB socket on your computer,the red LED will light to show power on. Open you music software program,e.g. Cubase,Sonar,MIDI connections, etc. Set the music in programs MIDI in and MIDI out devices to 'USB Audio Device'. Your USB to MIDI interface is now ready for use. To save potential problems,it is recommended that this interface is always connected to the same USB as it was originally installed on to prevent multiple installations of the driver

Reply to
Greegor

No =96 read my post carefully. I already have a USB adapter. I want to get this pc board (pictured) that hooks into a keyboard it's associated with working (it's missing the PC interface that supplies it power), and plug in my USB-MIDI adapter to it.

Anyway, to continue the story, I hooked up a power supply (to ground on the connector shield pin and pin 8), hooked up the keyboard and the USB adapter to it and the computer, and no go: no MIDI signal. Didn't work. Dont' know if it's related to the fact that I accidently broke surface-mount resister R2. What is the value of R2? It says "472" on it. Is that just ohms, or K ohms, or what?

Reply to
Zephinilium

Anyway, to continue the story, I hooked up a power supply (to ground on the connector shield pin and pin 8), hooked up the keyboard and the USB adapter to it and the computer, and no go: no MIDI signal. Didn't work. Dont' know if it's related to the fact that I accidently broke surface-mount resister R2. What is the value of R2? It says "472" on it. Is that just ohms, or K ohms, or what?

4.7k
Reply to
Ban

472 on a surface mount would mean 4.7k-ohm, and that's a very common value in a 5-volt system for a pull-up resistor.

Check the obvious stuff first.

Are all the voltages right on the 8051?

40 and 31 should be high. 20 low. 9 low after initial reset. The rest could be anywhere.

Is the chip (8051) coming out of reset? Pin-9 is the Reset line. A high on this pin for 2 clock cycles will reset the chip.

Is the crystal oscillator running? Crystals can fracture if dropped, mistreated, etc... The 8051 has a pretty hefty osc. circuit. You can probe it with a scope or logic tracer without killing it. You're not as worried about amplitude; only that's it's running.

Are you getting any signal on the ALE (Address Latch Enable) pin 30?

Are you getting any pins toggeling on the output ports?

The board may need an external MIDI clock input before it will appear to be doing much of anything (?) So, if everything else above looks OK, start checking out your MIDI IN setup.

From the photo, it doesn't appear that any traces are going to Port-0 (pins 32 through 39) This pins double as the low-order address and data pins in the even the 8051 wanted to use off-chip program memory (say from an EPROM - Remember those?) If they're not used, it means the program resides inside the 8051, which is very common, and simplifies your troubleshooting considerably.

Can you post the back side (solder side) of this board?

-mpm

Reply to
mpm

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So you're saying that the keyboard itself is not MIDI??? So you just want to power this board to UART the serial keyboard (2nd DIN from firewall?) and pass it to the MIDI ports?

Aren't the MIDI ports on a card like this geared to pass to the PC bus?

At the top edge of this picture (cut off) there is no PC edge connector?

The two ribbon connectors fed to the other card you say powered it?

And from there everything went to and from the PC bus?

Technically those two ribbons could be two more MIDI ports, if there is a PC bus edge connector clipped off from the photo.

Are you trying to replace the missing card and tie this into a PC bus?

The code on the 8051 is probably strictly passing to/from the bus. Bridging from the keyboad to the MIDI ports would have been done IN the PC, not within the 8051 code.

If you eBayed this make and model of keyboard and card how much do they sell for? If you bought another one it would have the second card which plugged into an 8 bit XT ISA slot, right? Because of that it would probably be dirt cheap, right?

How much do old MIDI keyboards sell for?

What make and model IS this keyboard?

I thought that at least at one point an 8048 with EPROM could be replaced by an 8051 with the code masked, but it took production quantity to make masking worth doing.

I discovered a Multitech modem way back that used an 8048 and EPROM so that those few people who paid for real estate MLS would have their ID and password coded into the EPROM and they thought that they had high security. Except that all a service thief would have to do is send an "enquire" code ASCII 05 and the box would answer with the ID and password.

This enquire and answer functionality was commonly used on Teletypes with a paper tape unit to start the tape reader.

Early PC ""modem software"" like the shareware Qmodem emulated the same function all in software on the PC/XT/AT.

Not only was this really lousy ""security"" but the use of the 8048 and EPROM rather than masked 8051 meant that the modem had a notorious problem with overheating.

I think their bottleneck was that if you got 1000 8051's masked they would all be identical and could not have individual username/passwords in them.

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That's the masked one isn't it? In the original Intel parts at least?

It's from 30 years ago for me.

Reply to
Greegor

Each to their own. I would just get a couple of the things found with=20 this search string "usb to midi adapter". You may even be able to = include=20 the quotes.

Reply to
JosephKK

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I'm not the OP, so I have no idea really what he's trying to do. (Other than get the board running.) I have no idea what it talks to, or what kind of system he's trying to cobble together. The board in the JPG looks simple enough. Whether it needs external (whatever), I cannot say.

Me: I have a Yamaha P-80 digital piano and a Kurzweil K2600. But honestly, I don't use the MIDI on either of them. Well, occasionally I'll hook up my Roland PMA-5 for teaching or ???.

MIDI can get pretty complicated, if that is your desire.

-mpm

Reply to
mpm

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