ST536 STE EDITION

[exxos]

Went back to @Badwolf STE536 and totally unstable again. Long story short, I think those PLCC EPROMS are just evil. It causes ROM shadow copy to fail.. So I think TTram is broken.. Then it locks up trying to get to desktop.. So I assume booster / TTram unstable etc.. but it wasn't the case.

I swapped the ROMs around with my STE536, both STE536 now work fine.. I wonder how much time I have wasted on that issue without knowing it.. Its annoying as even ROM CRC passes.. So you would assume ROM to RAM copy failed, so TTram issue.. but seems not! So that sucks right there !

So I am officially banning eproms in the ST/STE536 now !

[exxos]

Looks like a bad bit after several tests :shrug: I mean it passes 0000, FFFF, 0101, 0202, 0404, 0808, 1010, 2020 and own address test every time and fails every time on 4040 test.

2 totally different test runs...

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[exxos]

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Been playing around and currently it is passing again by inverting the clock (what I did on the original ST536 as well)

On the ST536, I had to use a 2ns buffer, but even that wasn't enough on the STE536.. at least with badwolfs board.

The puzzling thing in all this though, is why some boards need a 5ns shift on the CPU and others don't. I mean tolerances will play a part and indeed PCB tolerances but for them all to add up to like 5ns.. seems unlikely.. But here we are...


Same firmware, same revision STE536 (mine not badwolfs)

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That board works fine with non-inverted firmware.

I do have a few more resistors on lines on bad Wolves board than I do.. So I will put those resistors on my board but I doubt that is the issue...

EDIT:

So my board now works with resistors in place. That's going to be "fun" for beta testers to do :)

[exxos]

So interestingly generally is D14 and D15 failing.. And they just happened to be the shortest traces as well...

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The mean is bizarre to think just a few millimetres of track length can have such a huge impact...

I have half mistakenly gone with the philosophy of shorter is better because signals reach destinations sooner.. so faster = better..

BUT

OTOH, they are also quicker to release.... It is likely where these issues are originating from..

[exxos]

EXP4 firmware is out.

https://www.exxosforum.co.uk/atari/last ... /index.htm

The pull-up resistor on BGACK and 330R on the CPU clock are the main mods to do when flashing EXP4.

EXP4 has been tested on my STE (internal blitter) . DOTT, GB6, IDE, TT & STram tests all pass for ~24 hours constant run.

I'm not spending any more time on this project for the foreseeable future now. It's in the hands of the community if they purchase a board and help with testing from this point forward.