I got this from a computer with a fried mobo, and I'd love to be able to hook it up to some modern hardware, or a calc
From what I can tell, it's out of an older dell dimensions. The model number is 1X0-0488-001
12 pins isn't that much of a sacrifice for full-on hardware MIDI support! [/img]
Oh, and I did try google.
Nothing on pinouts or datasheets, or anything besides parts surplus stores, from what I've seen.
Do you happen to have a picture of the backside of the board, or is it useless? I did some Googling for you, and it's definitely a Yamaha MIDI synthesizer on a chip, but I can't find a datasheet or pinout either.
Well, from what I can guess, since it's apparently an "entire sound card" it's the Midi synthesizer plus some small hardware for sound output, run by an IO port or two. Not unlike what we do for calc sound
The back of the chip has a sticker with its serial number and the model number I posted above, but nothing else I could see.
The pinout/datasheet for the Yamaha part is relatively easy to come by, it's that TI chip that puzzles me. I presume it's used to turn the small number of exposed I/O lines into the larger number of I/O lines required to drive the YMF704 but can't find anything for it.
I'd suggest an SPI/I2C bus of some sort, but I didn't think those were really used in desktop/laptop computers. Benryves, where did you find the datasheet for that chip?
From my searches the TI chip is a "10 line to 4 line priority encoder" so I'm guessing you're right.
Here's a datasheet:
http://www.alldatasheet.com/datasheet-pdf/pdf/85977/TI/CD54HC147.html
Want to hear something cool? I've found this part (the whole board) for under $5 from online parts stores, so if it does become something cool it's easy for others to replicate.
KermMartian wrote:
benryves, where did you find the datasheet for that chip?
I missed this post, sorry: plug YMF704 into your favourite search engine and you can find plenty of results. 
Here's an appropriate one if you still can't find it.
Edit: KermMartian wrote:
I'd suggest an SPI/I2C bus of some sort, but I didn't think those were really used in desktop/laptop computers.
They most certainly are. I²C is the most obvious one externally, as it's used to read the EDID from VGA/DVI/HDMI monitors using DDC.
And aren't there I²C drivers written for the calculators, iirc ben you even wrote one of them. So if that is indeed an I²C chip would it be possible to use it to start having your calc make some midi magic with this thing?
We still don't know what the 75A6HJF/HC14 chip is. I'm not convinced it's the "10- to 4-Line Priority Encoder" as that takes ten inputs and produces four outputs (whereas we are expecting something that turns few inputs into many). The model numbers are pretty different as well (54/74 prefix, not 75) and, most concerning of all, the pin count doesn't match (16 v 14).
If I knew which were the power pins I might be able to probe it to get an idea of what the other pins do. That should at least give away whether any are input or output (or at least output
)
I would presume that the power pins would be shared between the YMF704 and the TI mystery chip. The top left and bottom right pins are usually a good place to start - you can probably even follow the copper by eye and not need to resort to a continuity tester.
I got some extra, useful info from TI on the chip: It's a Hex Schmitt-Trigger Inverter.
Here's the email I got from them (TI's Microcontroller end is far more friendly than their Calculator end) after I sent off an email asking about the chip
Quote:
Hello William Shipley
Thank you for contacting Texas Instruments Product Information Center. In using the part marking HC14 to identify the part. The following are the results.
Device Name Description Marking
SN74HC14D Hex Schmitt-Trigger Inverters HC14
SN74HC14DBR Hex Schmitt-Trigger Inverters HC14
SN74HC14DBRE4 Hex Schmitt-Trigger Inverters HC14
SN74HC14DBRG4 Hex Schmitt-Trigger Inverters HC14
SN74HC14DE4 Hex Schmitt-Trigger Inverters HC14
SN74HC14DG4 Hex Schmitt-Trigger Inverters HC14
SN74HC14DR Hex Schmitt-Trigger Inverters HC14
SN74HC14DRE4 Hex Schmitt-Trigger Inverters HC14
SN74HC14DRG4 Hex Schmitt-Trigger Inverters HC14
SN74HC14DT Hex Schmitt-Trigger Inverters HC14
SN74HC14DTE4 Hex Schmitt-Trigger Inverters HC14
SN74HC14DTG4 Hex Schmitt-Trigger Inverters HC14
SN74HC14NSR Hex Schmitt-Trigger Inverters HC14
SN74HC14NSRE4 Hex Schmitt-Trigger Inverters HC14
SN74HC14NSRG4 Hex Schmitt-Trigger Inverters HC14
SN74HC14PW Hex Schmitt-Trigger Inverters HC14
SN74HC14PWE4 Hex Schmitt-Trigger Inverters HC14
SN74HC14PWG4 Hex Schmitt-Trigger Inverters HC14
SN74HC14PWR Hex Schmitt-Trigger Inverters HC14
SN74HC14PWRE4 Hex Schmitt-Trigger Inverters HC14
SN74HC14PWRG4 Hex Schmitt-Trigger Inverters HC14
SN74HC14PWT Hex Schmitt-Trigger Inverters HC14
SN74HC14PWTE4 Hex Schmitt-Trigger Inverters HC14
SN74HC14PWTG4 Hex Schmitt-Trigger Inverters HC14
The base part number is SN74HC14 and depending on package type (PDIP or SOIC)that would indicate how the device was placed on the board. If you have additional questions please reply to this email
Thank You,
Orlando Richardson
Texas Instruments
Semiconductor Technical Support
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