MOS 6571 Amiga keyboard controller dissection > 6500/1

[ttlworks]

And that's all for now.

[BigEd]

Marvellous work! It really jumped out at me that the CPU core is a very different aspect ratio. And then, I spotted that the PLA is folded. Wow.

Very interesting that RESIRQ does double duty, that the ADH latches are moved to the decoder outputs, that RDY has been stripped (how many transistors does that remove??)

And RnW is multiplexed with D2 - completely unexpected!

And this - wonderful!

ttlworks wrote:

Oh, and during a Reset a "write" is forced for initializing the I/O ports with 0xff.

[ttlworks]

Thanks, Ed.

After I noticed that the 6502 core in the 6571 appears to be a redesign of the NMOS 6502,
I just could not resist taking it apart at transistor level to see what might be different.