Thanks for the replies - I'm going to have to see how fast my new board will run at once it's built!

Hi!

Has anyone run a QFP wdc 65c02 at 20MHz? - looking at the datasheets(and for supporting chips), this would seem to 'imply' that it's possible (seems to stop at about 19MHz in the sheet).

My bus length is about 3cm, so this is quite interesting after looking at the datasheet - I remember on ...

Had some more time to play again - found that ram really needs to be gated (as mentioned in lots of places here) and fixed a few missing things like the RTC i2c lines (etc, etc) and a stupid mistake with a7/a8 being mixed up on one of the 'address select' proms so that I now have a 'working' system ...

Not had much time to do anything since, so in the absence of any progress here's the eagle schematic so far (usual disclaimers) - ideas used/adapted from various sites whilst teaching myself

yes, there are probably lots of better ways to do some things!

Hi!

Now on v3 of the board (v2 had an arse-up where I trusted an LBR file for the ethernet chip to be 'correct' when it in fact it had transposed pins). Couple of changes - addition of a backplane connector for a custom backplane, extra flashy lights just because, and adding sdcard bits). Hopefully ...

Latest update since I have a moment to work on this again:

It lives! (in a really simple sort of 'make it do something to test the IO' fashion:

https://youtu.be/ILPir9XlJtY

That's a video of it booting up at 90Hz so you get to see 'stuff' happening

V2 board, couple of 'fixes' applied(nothing ...

Hi! Been a while - had some more time to spend on this project, so here's an update! Hope it's useful and interesting!

The V1 board was PERFECT SUCCESS! (apart from a total cockup with the 1M ram chip paging - which I'm blaming getting distracted, and the MAX ACPA chip voltages)

V2 is now ...

From where are you getting these 45ms EEPROMs?

ebay - the chips in question are:

https://www.digikey.co.uk/product-detail/en/winbond-electronics/W27C512-45Z/W27C512-45Z-ND/1133334
and (a one time programmable version)
https://www.digikey.co.uk/product-detail/en/microchip-technology/AT27C512R ...

All going well so far - it's running and I'm just waiting for an eeprom so I can make the 'memory map' work (used a 45ns eeprom so I can efficiently organise the addresses)

Captain klutz has prevalied though - apparently I didn't read the MAX690ACPA datasheet properly and missed the bit where it ...

First time powerup with most of the important bits installed to check for magic smoke and other bits - nothing on the CS, so 'floating' data bus. 'Random' instructions executed until things stop.

Every 1.6 seconds the watchdog chip pulls RESET low (last 3 leds on the 'address bus' LED array are IRQ ...

Yep, those are excellent suggestions and the proper way to do it ;-)

Unfortunately not the road I'm taking this time... Important logic is socketed though, and will be fairly straightfoward to debug (have most of the kit to do this fortunately). The only big issue is if I need to do track mods (it ...

Boards arrived today - lots of checking to do then lots of soldering!

Hi!

Yes on the ground planes - it's only the top pour which didn't get grounded (the bottom one did). The board is already in the process of getting fabbed and I'm not to worried at this point about it, but yes the next version will be fixed (and better checked for that) as well as all the ...

Hi!

A yes on the schematic (once I've found out if it's working or not - I want to find out myself if I messed something up badly ;-))

The ROMS are for whatever ideas I have - at some point,... /if/ this all works out :) , I'll probably opensource all the bits.. a fairly big if at the moment as I ...

Hi!

I've spent a couple of days designing my first board (after messing about with a bit of breadboard so I almost know what I'm doing) using some of the info on here and around the net as well

Haven't done this before so it seems like an interesting project to do and learn stuff whilst I'm at it ...