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6805 pinout variations

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fabiodl:
In the process of reverse engineering the Sega SP-400 plotter, I found something weird. It mounts a HD6805V1, which according to
this datasheet is an Hitachi clone of motorola's 6805.
The problem is that the datasheet does not match at all what is on the board. The chip on the board has VCC on pin 40, gnd on pin 20, crystal on pins 5 and 6. The closest things I found are MC146805G2, which matches power, but not the crystal, and MC146805F2 which matches the crystal as well, but has less pins (I guess less I/O).
I would like to dump the content as done here but I have no idea on where the ports are located. The plotter board does not give particular clues, other than that pins 25 to 32 are probably the same port.
Have you ever seen a version that matches the pinout I have?
 

Benta:
The Hitachi HD6805 is an ancient NMOS MCU. There is no guarantee that an MC6805 equivalent exists for the "V1" version.

And what do you expect to do? These are mask programmed parts, you can't read them.

srb1954:
Closest match would be a Motorola MC6805R3 which is also available in a EPROM programmable version, MC68705R3. It seems to match the Hitachi device pin-out closely except the analog functions on the Port D lines are different.

As Benta points out the Hitachi part is a mask ROM device so there is not much chance that you could replicate the functions of that device unless unless you have the source code or binary code to program a new part.

fabiodl:

--- Quote from: Benta on September 25, 2021, 07:18:30 pm ---The Hitachi HD6805 is an ancient NMOS MCU. There is no guarantee that an MC6805 equivalent exists for the "V1" version.

And what do you expect to do? These are mask programmed parts, you can't read them.

--- End quote ---

I just hoped the NUM pin works as stated here


--- Quote from: srb1954 on September 26, 2021, 01:01:28 am ---Closest match would be a Motorola MC6805R3 which is also available in a EPROM programmable version, MC68705R3. It seems to match the Hitachi device pin-out closely except the analog functions on the Port D lines are different.

--- End quote ---

It matches the datasheet, but not the actual chip! That is why I am posting in the first place.  Have a look the attached pictures.

Nusa:
Try this version: http://datasheets.chipdb.org/Motorola/6805/146805E2.pdf

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