EDIT: I have moved this topic to AnyCPU.

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Want to design a PCB for your project? I strongly recommend KiCad. Its free, its multiplatform, and its easy to learn!
Also, I maintain KiCad libraries of Retro Computing and Arduino components you might find useful.

Interesting indeed - thanks for sharing. Would I be right in thinking that the busses are narrow - the address spaces are limited - not so much because of machine's capabilities, but because of a 40-pin periphery?

As it stands, no, it would be very difficult to expand the memory size of RAMON5 without a drastic redesign. Note that the only things which directly access memory use 8-bit registers as pointers. Making the registers 16-bit would require increasing the number of chips drastically - not that surprising, but I mean more than double the required chips, as the BSU would quadruple in terms of chips too... you'd end up needing something like 140 chips, which is impractical for homebrew construction methinks.

In principle the Instruction address space could be expanded fairly easily, though the longer the addresses the more bytes would be taken up in the already limited memory space each time you call a subroutine or interrupt, and the more cycles would be required to fetch each byte of the address in jump instructions.

I have toyed with making a RAMON6 architecture every now and then which is a 16-bit throughout machine, alieviating the memory space issues, but I've never been able to come up with something I like the feel of. I am also aware I could implement some kind of X/Y combined register scheme in an 8-bit machine as is very common (e.g. 8080) but I'm afraid that non-linear and/or segmented addressing gives me the heebee-jeebies and I'll do anything to avoid it. That includes the 6502's X&Y register addressing schemes. I know why they did it and I know its elegant in its own way, but its just a preference and I dislike it.

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Want to design a PCB for your project? I strongly recommend KiCad. Its free, its multiplatform, and its easy to learn!
Also, I maintain KiCad libraries of Retro Computing and Arduino components you might find useful.

Addendum: BigEd has informed by PM that there may be some "disquiet" because this is, of course, not 6502-related. If you want to take it down I'm fine with that, but give me a warning first so I can take a copy. It took a while to write

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Want to design a PCB for your project? I strongly recommend KiCad. Its free, its multiplatform, and its easy to learn!
Also, I maintain KiCad libraries of Retro Computing and Arduino components you might find useful.

You might want to change the topic title to "OT: The RAMON5 CPU Architecture" so prospective readers know it's not a design variation of a 6502.

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x86?  We ain't got no x86.  We don't NEED no stinking x86!

There's no need to delete your post. Generally, this forum tries to stay focused on the 6502 and related processors. Posts about new processor designs are welcome, but should have some content that makes them interesting to 6502 enthusiasts (e.g. the new processor is 6502-like, or the post compares the new processor to the 6502, etc). For completely off-topic processor discussions, there's our spin-off forum at http://anycpu.org.

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- Mike Naberezny (mike@naberezny.com) http://6502.org

I did not know about AnyCPU; I've moved the bulk post there.

_________________
Want to design a PCB for your project? I strongly recommend KiCad. Its free, its multiplatform, and its easy to learn!
Also, I maintain KiCad libraries of Retro Computing and Arduino components you might find useful.

It's a good question, but can I suggest you re-re-adjust this thread title to mention "addressing modes question"?

Don't worry, I already realised the stupidity of attaching it to this essentially dead thread. I'm going to open a new one.

I'm now declaring this thread dead. Two threads have been spawned to take up the various things brought up in it, so go to those:

Addressing Modes - what are they worth to you?
The RAMON5 CPU Architecture

_________________
Want to design a PCB for your project? I strongly recommend KiCad. Its free, its multiplatform, and its easy to learn!
Also, I maintain KiCad libraries of Retro Computing and Arduino components you might find useful.