exxos's Atari, Amiga & retro forum

Isn't the check for the external ROM about something like 4 instructions in from the beginning?

stephen_usher wrote: 16 Jan 2022 18:30 Isn't the check for the external ROM about something like 4 instructions in from the beginning?

https://www.exxosforum.co.uk/forum/viewt ... 990#p77016

Just to let folks know, this is still a work in progress, but as I am now over the main part of the soldering, I may not post on here as often, as it's now a case of double checking my work for connection errors and anything I've missed on both the top and bottom side of the PCB.

It will take me some time as my time in the evenings is about to get a little more limited due to being back at karate, but I will post anything that is of interest as soon as I have it :)

Great stuff, look forward to seeing progress. I used to do Karate back in the day. Both me and brother did. I didn't do it for very long but my brother carried on and really enjoys it.

I'm actually glad I sent you the board when I did because it would have just been calling out to me and tempting me to keep getting the board out and probably do a lot more damage than what was already done. So grateful for you offering to look at it.

Cheers,

Brett

BrettRogersUK wrote: 20 Jan 2022 14:45 Great stuff, look forward to seeing progress. I used to do Karate back in the day. Both me and brother did. I didn't do it for very long but my brother carried on and really enjoys it.

I'm actually glad I sent you the board when I did because it would have just been calling out to me and tempting me to keep getting the board out and probably do a lot more damage than what was already done. So grateful for you offering to look at it.

Cheers,

Brett

No worries Brett, I'll do what I can. I'm in my 14th year of karate now, and hoping to go for my 2nd Dan grade this year.

Spent some time today verifying my wiring again by buzzing it out. Having a schematic in Kicad where I can highlight traces is definitely a huge help here, rather than trying to follow Atari's musty old drawing!

I confirmed that VCC and GND were all good across both sockets, and all of the address lines are correctly wired as per the schematic. It did highlight a minor error on my part with 1 wire incorrectly placed, so I rectified that.

The final check is the data lines, and I think that is where the problem lies as comparing to my working machine, at least 1 data line isn't behaving the same.

More buzzing out to come!!

Bzzzzzzz!

Probably worth checking you have 10k etc pull up resistance on all the ROM and CPU pins.

exxos wrote: 23 Jan 2022 00:12 Probably worth checking you have 10k etc pull up resistance on all the ROM and CPU pins.

They look original, and funnily enough I haven't changed them in my own STE. But I can change them whilst I'm at it, but reluctant to change too much else until I am 100% sure I have all the wiring right.

Good call though.

rubber_jonnie wrote: 23 Jan 2022 00:14 They look original, and funnily enough I haven't changed them in my own STE. But I can change them whilst I'm at it, but reluctant to change too much else until I am 100% sure I have all the wiring right.

I half recall bodge wires to resistor packs at one point ? I know you metered a lot out. But checking the pins actually have pull ups will check a lot of traces etc as well. The actual resistance *shouldn't* matter at this point..

Also not sure if you're pressing reset button during tests ? Would be typical to actually have fixed it and the reset circuit died...