SuperCPU for my C64 and C128

Hi Guys,

 I'm Luis Rene and I'm new in this forum. I'm interested in trying to
develop a SuperCPU replica for my Commodore 64. Recently, I’m trying to
understand the C64. I wanted to get into the retrocomputing passion due to
I wanted to understand how old computers works and how they were
conceptualized and designed. While searching about how the C64 works and
buying 6510 CPUs (for future replacements), I saw on eBay the SuperCPU
costing hundreds to thousands of dollars. Hence, the SuperCPU left me
intrigued. So, I decided to contribute with something with the community.

 I'm a FPGA designer and I thought that SuperCPU replica is a good project.
However, there is not much technical information about the SuperCPU and
time ago I decided to leave this project for a while.

 In these days, I wanted to try again after almost a year…

And I would like to ask for help. I can’t find enough technical information
to understand how the SuperCPU works. I can't find information about the
booting process, how is the signaling exchange between the C64 and the
SCPU, how are the bytes load/store operations or simply memory management
between the C64 and the SuperCPU. Also, how the SuperCPU chances its
operation during the turbo/normal mode, the JiffyDOS, etc. There is some
information, but for me is a little ambiguous. Unfortunately, I’m a little
stuck due to my lack of information, etc., of the C64 as well as the
SuperCPU (which it is not available and I haven't touch one). I understand
electronics, FPGAs, however, I don't understand in detail how the C64 and
SCPU systems work together at firmware level.

 With respect to my project in a prototype process, I'm considering work
with a FPGA + 65816 chip for achieve a replica of the SuperCPU. Later I
will check to implement everything within a FPGA. I've visualized the
modern SCPU+ with more features or advantages. I visualize to offer
reconfigurability or versatility for machines like C64, c128, trying to
solve the issues of the SCPU in his days.

Because of this, that it is required to design a reconfigurable 6502-based
CPU... in other words a reconfigurable CPU with includes a *6510, 8502,
65C02, 65C816* and *Also *a *16bit architecture of the 6502/8502* with
illegal opcodes in a way that allows compatibility defined by the user.

I understand the concern of the community related to the frustration or
rejection of the user experience playing games or running programs between
1Mhz and 20Mhz. I think will be interesting for user and developers to
customize several parameters. I imagine a SuperCPU but with more
capabilities like a wide range of frequency operation from 2Mhz to 50Mhz
that you can tune any time. For developers, a debugging tool in hardware in
order to set breakpoints and run step by step your programs in real HW.
Sorry, maybe these are stupid thinks, but I'm trying to propose ideas that
can improve the actual SuperCPU conceptualization. I've read several
reviews showing the bad things about the SuperCPU. That's why I was
thinking in a new SuperCPU with more advantages.

I hope you can give some guidance, feedback of the goals as well as some
technical information about my hobby project.

Luis Vela

dsp8bit

twitter @LuisRene5