ST536 STE EDITION

[PhilC]

Might be worth re-looking at Maprom to see how it changed the rom pointers and then copy that?

[exxos]

Might be worth re-looking at Maprom to see how it changed the rom pointers and then copy that?

It uses the MMU to to the address translation. So the CPU sees 206 space but the MMU redirects it to TTram. Such a huge MMU table is why you loose a bit of speed because of the extra overhead.

What I'm doing is similar. The CPU still thinks it's accessing 206 space. BUT I fiddle the address so it goes to TTram. The SDRAM controller is nonthewiser as it only sees TTram access like normal. It's very simple idea... It should work but I'm not much good at verilog. So I've probably screwed up some stuff. But I don't see what.

[exxos]

I found a Verilog AI. It states my address translation is likely delaying the address which the RAM controller is seeing and basically screws up all the timing I mean I suppose it is possible...... but that would mean my idea would simply never work

I tried not using AS30 to see if I could gain a few extra ns that way. but no change But it likely upsets the BURST timings as well. I disabled BURST for ROM but still no joy.

So assuming that's the issue, SRAM is the only way it would really work.. Thats fine I guess, its only like £3 a chip anyway. Just a PITA to respin the board again. Might have to be a "next year project" as its all soaking to much of my time up currently.

[Steve]

Hey @exxos I seem to have continuity between these two pins (Sorry I'm not sure the pin numbers) Can you easily see if they're supposed to be connected? I think they go to that via?

xilinx.jpg (597.1 KiB) Viewed 1376 times

[Steve]

If my uploaded image is garbage, please see the Google drive upload instead.

[exxos]

If my uploaded image is garbage, please see the Google drive upload instead.

If they are GND.....

viewtopic.php?p=128131&hilit=Short#p128131

Yeah your image just shows as vertical lines...

[Steve]

Yeah I think they're GND... I just buzzed them to the GND header, it's just so hard to see, I need a microscope! But yeah I think they are.

[exxos]

Yeah I think they're GND... I just buzzed them to the GND header, it's just so hard to see, I need a microscope! But yeah I think they are.

You don't have any sort of magnifying thingy ? I wouldn't even consider soldering one of those chips without one these days.

[Steve]

Yeah I think they're GND... I just buzzed them to the GND header, it's just so hard to see, I need a microscope! But yeah I think they are.

You don't have any sort of magnifying thingy ? I wouldn't even consider soldering one of those chips without one these days.

I've got an old-fashioned one-eye-piece magnifier I use, but it's no good when I'm trying to hold two multimeter probes lol I've checked it all out and my soldering looks good. I'll program it tomorrow because I had to ultrasonic it again tonight, want it to thoroughly dry out. I also noticed there seems to be some flux residue on my 030 CPU pins, so I'm soaking them in alcohol over night to make sure they're nice and clean.

[PhilC]

@Steve take some high Res pics with your phone and zoom in to check them if you have no microscope. BTW I only use a cheap USB one and that's been good for everything I've done so far.