Recording request: NEC µPD7756C and the Mitsubishi M50805
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Re: Recording request: NEC µPD7756C and the Mitsubishi M5080
I found another Aerobics cart for $12, so I bought it and decapped the chip in the one B00daW sent me: http://seanriddledecap.blogspot.com/201 ... -post.html
The 312-byte decoding ROM is easy to spot, but unfortunately the 960-byte parameter ROM seems to be implant ROM, so I can't see any of the bits.
The 312-byte decoding ROM is easy to spot, but unfortunately the 960-byte parameter ROM seems to be implant ROM, so I can't see any of the bits.
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Re: Recording request: NEC µPD7756C and the Mitsubishi M5080
I needed a primer on PARCOR/LPC, and Cater's Electronically Speaking has a good introduction: http://www.seanriddle.com/lpc.pdf
As Lord Nightmare said, this looks a lot like TI's LPC.
As Lord Nightmare said, this looks a lot like TI's LPC.
Re: Recording request: NEC µPD7756C and the Mitsubishi M5080
So the decoder ROM is in the middle left and the parameter ROM is on top?
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Re: Recording request: NEC µPD7756C and the Mitsubishi M5080
Yep. The decoding ROM bits are easy to discern, although I haven't tried figuring out the layout. I can't see any bits in the parameter ROM.
The top left pad is pin 4, numbered counter-clockwise. It's easy to spot the power inputs and the huge drivers on DA0 and DA1. The 2 pads in the lower right aren't connected to anything. There's an extra pad, so I assume the 22-pin and 24-pin versions use the same die, but clock output isn't pinned out in the 22-pin version.
I put more info here: www.seanriddle.com/m50805.html
The top left pad is pin 4, numbered counter-clockwise. It's easy to spot the power inputs and the huge drivers on DA0 and DA1. The 2 pads in the lower right aren't connected to anything. There's an extra pad, so I assume the 22-pin and 24-pin versions use the same die, but clock output isn't pinned out in the 22-pin version.
I put more info here: www.seanriddle.com/m50805.html
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Re: Recording request: NEC µPD7756C and the Mitsubishi M5080
sean, can you take a hi-res image of the smaller, visible rom area? I should be able to get the lpc tables extracted, but I need more zoom.
LN
LN
"When life gives you zombies... *CHA-CHIK!* ...you make zombie-ade!"
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Re: Recording request: NEC µPD7756C and the Mitsubishi M5080
Here's the decoding ROM at 3Kx4K pixels: http://www.seanriddle.com/m50805metaldecodingrom.jpg
And I uploaded a 32Kx32K pixel full die shot to WikiMedia: https://commons.wikimedia.org/wiki/File ... tal20x.jpg
And I uploaded a 32Kx32K pixel full die shot to WikiMedia: https://commons.wikimedia.org/wiki/File ... tal20x.jpg
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Re: Recording request: NEC µPD7756C and the Mitsubishi M5080
And here's the decoding ROM with the top metal removed: http://www.seanriddle.com/m50805aciddecodingrom.jpg
Re: Recording request: NEC µPD7756C and the Mitsubishi M5080
So looks like we could read the decoder ROM to assemble a binary from it... What do you think the next logical steps for the parameter ROM should be? Lord Nightmare?
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Re: Recording request: NEC µPD7756C and the Mitsubishi M5080
The 960 byte rom may require etch/staining, which is outside my realm of expertise
However it is likely we have the entire contents of it anyway from the data line traces?
LN
However it is likely we have the entire contents of it anyway from the data line traces?
LN
"When life gives you zombies... *CHA-CHIK!* ...you make zombie-ade!"
Re: Recording request: NEC µPD7756C and the Mitsubishi M5080
Is there any program made that can analyze a decap picture through filters and bitmap (with proper image setup and formatting) to create a dump?
I'm not sure what I'm looking at regarding which is a 0 and which is a 1 regarding the decoding ROM decap...
I'm not sure what I'm looking at regarding which is a 0 and which is a 1 regarding the decoding ROM decap...