If you click through from Coltek to the shop you get to the ebay listing that the original poster mentioned, so I guess he does actually have genuine parts.

Ahh, thats good to know, Im guessing thats why he was recommended, ive just had a look, my 65c22 from there looks good, my 65c02's from elsewhere are a mess (bent pins, some gunky glue on top of them etc)

That scale model looks awesome, in a previous hobby when I had space, I had a metal workshop (CNC Mill, Lathe etc) where I made miniature petrol engines, so I have an appreciation of what can go into that sort of work (and for the cost, buying Aluminium stock always hurt)

As I get older im trying to calm down on switching hobbies, In the past I tended to get just good enough to be dangerous, and then move onto something else (it's a common thing with autistic people). I do often come back to Electronics/Computers in some form tough, whether RC Model Helicopters, Software Defined Radio etc. I think I just always need to be learning something.

In the past when my father had better eyesight he was really in to OO scale model trains (obviously a different ball game to you large scale stuff, more off the shelf parts etc), and often had me building stuff with PIC chips for him to help automate the signals etc (pre arduino days), I can remember I had trouble getting compilers and things to work back then so I ended up using one some Dutch guy wrote which worked flawlessly, only problem was it was his own language/syntax and so all the commands were dutch words, I got quite proficient at it despite not speaking a word of Dutch.

Thanks, I will take a look at some of those, makes sense to be using what others are when I have so much to learn. Im taking it Vasm doesn;t get used much here?

Just to note, fans of Basic, BBC Basic, or Acorn's BBC Micro might enjoy Beebasm, an assembler embedded in something rather like BBC Basic. Or at bbcmic.ro (Owlet IDE) you can play with small examples. If you want to learn from scratch or explore small code snippets, easy6502 is very handy.

That Easy6502 looks great, something for my weekend reading

Wow, I love this tip. I'll need to order some conventional 28-pin wide sockets but this makes so much sense to me. Especially since I did pick up one of those slimmer cuter ZIF style sockets you mentioned.

_________________
https://github.com/Individual-Solid/

_________________
http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?

Yes, there's lots easy6502 doesn't offer - I'd hoped to convey that in what I wrote! (But it's a great tutorial for beginners, and a handy place to try short snippets of code.)

Just a quick update,

I put together a quick reset circuit from a 555, it's way overkill in that it gives a 2s delay. But it works consistently, regardless of whether power is initiated from the PSU, switch or pwering on it RST held and then released

Now just waiting om ordering a new PCB, DS1813 etc

Thanks guys

Ok, so ive been working through my re-design of the PCB's and trying to apply what ive learnt from you guys and Garths primer.

Ive taken a lot from Grant Searles 6502 design, and added a 65c22 (same address spaces as $6000 - $6FFF was free on Grants design, so I could wires it up the same way it was on the original design.

Ive got the DS1813 reset circuit, decoupling caps for every chip, and tied the extra lines via 3.3k.

Also added the serial interface, and additional board for video/keyboard based on Grants design.

I think if I can get this to work, then I can start looking at my own changes etc as I learn more.

I want to do a bit more validation etc before getting the pcb's ordered.

The Memory Map should be:
0000-7FFF 32K RAM
8000-9FFF VIA
9000-9FFF FREE SPACE (4K)
A000-BFFF SERIAL INTERFACE
C000-FFFF 16K ROM

But im worried whether ive miscalculated on the VIA being at $8000? Is tying A15 and inverted A15 to CS1 and _CS2 the right approach?

But advice welcome as always

If you want you VIA respond to address in the $8000 or $9FFF range then you need to decode the 3 address lines A13 to A15, not just A15.
A15 high decodes every address from $8000 to $FFFF.
IF you want just the $8000 to $8FFF then you'll need to include A12 as well.

If you look at the binary values
then it becomes obvious what address lines need to be dcodes, and at what level.

For the larger range you need A15 high, A14 and A13 low. So if A15 goes to the active high chip select then that means (A13 OR A14) needs to be fed to the active low, as if either of the address lines is high the address is out of the range required.

For the smaller block, that would A15 again to the active high select, with (A14 OR A13 OR A12) to the ative low.

For running at slow speeds, the simplest decode method to add IO devices to Grant's design is to use the 74HCT138. The 138 has 3 selects one high and two low. So will decode the $8000 to &9FFF memory area without any additional support. Wiring A10 to A12 to the A, B & C inputs gives you 8 device selects each for a 1k block within that range.

Awesome Thank you, I had a suspicion it wasn't right, still struggling to calculate them, I made the mistake of only looking at the binary for $8000 which is where the A15 came from, but can see now where I went wrong.

What would you consider low speed for the 74HC138? I guess it is simpler to do the OR of the A14 & A13 for this one? Ive got nothing else to put in that address space.

Why are you using that 68B50? That UART doesn't have a baud rate generator and is not CMOS-compatible. See if you can track down a non-WDC 65C51.

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

That's relative, and depends on the CPU etc. A little digging in data sheets and some maths is required.

The modern W65C22 needs the chip selects stable 10ns before the clock rises, so chip selection has to be completed in 10ns less than the low half of the clock cycle.

The data sheet for the Nexperia HCT138 says worst case propagation delay at room temperature is 40ns. Other manufacture's parts may not be exactly the same, but will be similar.

If you've also got the WDC 65C02 then that has a worst case of 30ns from the clock going low to address being stable when running at 5v.

Add the three valuess together and that's 80ns minimum for the clock to be low for the chip select to meet all of the specified maximums. That is then 160ns for a complete clock cycle, which works out at 6mhz give or take a few fractions well short of what the CPU is capable of.

The older 65xx parts will have longer setup times and a lower maximum clock.

That's not to say you can't run faster than that it's just not guaranteed.

NB if you do have all WDC parts then the HC138 is also suitable and a little faster. The "T" part is designed to cope with TTL inputs ie NMOS 6502.