who in their right mind ships a 65816 hobbyisy board but (apparently) doesn't document the memory map? The memory map is a crucial bit, because that's what tells you where all the VIA/PIA/ACIA registers are. And also, there's apparently another memory mapped page in RAM that's shadow for all the vectors usually found from $FFE0 on.

@lee4hmz It's WDC's 65C816 SXB board (though that's a tad expensive for "hobbyist" territory, I admit). Their cheaper SOCs have different layouts in terms of memory map.

There's a reason RasPi dominates the SBC market in the wake of other, "better" boards: their community has pretty much complete dicumentation of the thing.

(I did find a small table in the "datasheet" that was the memory map, in the end ;o)

WDC seems to have no idea about usability or documentation. Pass the baton already to the HDL cores with open source licenses!


@yakkoj @lee4hmz

It's true, there's something about the 40 pin DIP.
And the 48 pin DIP. And the rarely seen 64 pin DIP.

And then there are Rockwell's very tasty QIP-format R6501Q and R6511Q



@EdS To my mild embarrassment, I still haven't actually played with any 6502 series chips. Something to aim for in 2018, maybe, although I still need to do something with the 68ks I bought recently as well. Too many projects, not enough time!

You can get started with easy6502 - from zero to snake in one big page.


And then you work up to visual6502!


Or is that working your way down?


@EdS Oh neat, thanks. This is an easy way to confirm or refute my long standing suspicion that actually working in that beautifully spartan assembly language instead of just admiring it would be terribly tedious compared to my lovely Z80. :p

@solderpunk @EdS Each is tedious in their own way. I prefer 6502 despite Z80 being the first CPU I coded in assembly for.

@vertigo @solderpunk @EdS I wanted to learn both in 80s but tended to use more 6502 ASM simply because I had an Acorn Electron at home, and BBC micros at school and these had an inbuilt assembler. I did try and build a dev system using a ZX Spectrum with Interface 1 I got second hand from a friend but by 1990 this hardware was already way obsolete and more importantly proper tutorials on Z80 coding were still hard to find (no internet yet and USA books aren't cheap)

@vfrmedia @vertigo @EdS IMHO good online material for the Z80 (especially written by people who understand that the Z80 and TI calculators are not, in fact, once and the same) is still hard to find. The 6502 folks definitely have a nicer range of good tech docs and a community at 6502.org which I kind of envy.

@solderpunk @vfrmedia @EdS I've found technical material on the Z80 to be more than adequate; retro-gaming sites sometimes even have cycle-by-cycle breakdowns of what the Z80A (specifically, as it was most popular variant) does. Undocumented opcodes, et. al.

I think the only thing missing is the forum, but the info is definitely out thert.

There's a nice piece about #z80 behaviour, and some good links, in this article about emulator fidelity:

It turns out that you sometimes need cycle-by-cycle fidelity which is much harder than instruction by instruction.

The RetroBrewComputers forum is good for z80 and 68k and other systems:

@vertigo @solderpunk @vfrmedia


@EdS @vertigo @solderpunk @vfrmedia I wrote a z80 emulator a while ago that choses readability over performance, I think it's a good resource to study the CPU:


It's been used as the basis of other emulators, too.

@sir @EdS @vertigo @vfrmedia Thanks for the link, I'll check it out!

Are you (one of?) the KnightOS author(s)? I read about KnightOS for the first time just a week or two ago, makes me wish I still had my old TI-83!

@solderpunk @EdS @vertigo @vfrmedia yeah, I am the lead dev on KnightOS. Started it... must have been 10 years ago by now

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