exxos blog - random goings on

[exxos]

Code: Select all

POKEW (&HE0AAAA),&HAAAA
POKEW (&HE05554),&H5555
POKEW (&HE0AAAA),&H9090

I just got home and quickly tried those numbers, but still getting the same as before Back to the drawing board I guess.

[keli]

It might be latching the data too late. According to the 68k manuals, the data may no longer be valid when R/~W is deasserted on a write cycle. Maybe you need to combine your WE with UDS and LDS, which are asserted low while data on the bus is valid?

[exxos]

I have delayed DTACK by another clock cycle, and terminated the flash stuff after the first clock cycle. So its got like 250ns to work with and should be plenty... When /AS goes low, the flash has like 250ns to setup and latch.. then another 250ns before the cycle terminates. So its running a lot slower than the max delay time in the datasheet.

I've pretty much hit a wall with it now, I can't think of anything else to try. Only option left really is to fine some other brand of flash and give that a try

[exxos]

Got the next H2 printouts thanks to the Icky family..

So can do a bit more work on checking alignments with a original board now

IMG_4430.JPG (295.21 KiB) Viewed 1401 times

[PhilC]

Surely you've spelt glitter wrong

And is that an angled simm socket? Might be better rotated 180 degrees if it's the way round I think it is.

Other than that, looking forward to seeing the finished article.

[exxos]

Its the same socket as on my falcon ram boards. Doesn't matter which way it goes really. Just thought it be easier if the simm plugged in from the front end of the board.

[exxos]

As per usual nothing can ever be simple

Long story short, Eagles print driver sucks and the motherboard being 440mm actually comes out at 438mm.. This explains why I have been having so much trouble lining up the holes & connectors etc.

So after multiple prints, I have found a calibration factor (1.002) which brings it back to 440mm.. I am using A3 paper in my printer as it just fits that way.

z.jpg (137.98 KiB) Viewed 1394 times

So now I need to check all the holes yet again, and start moving stuff about yet again, now I know the correct scale factor to be working at.

Looking on the Internet, it seems this has been a bug in eagle for a really long time

[PhilC]

[exxos]

All of the connectors and holes should now be correct... I started putting in the outer border which is just tinned copper...

zz.jpg (234.91 KiB) Viewed 1375 times

[exxos]

Outer via's ( I think there was like 300 of them! ) and copper border top and bottom done. Also done the flat lug things for the PSU holes.. Added in the cartridge holes and the connector was aligned up properly. The back floppy posts were 0.5mm out, so fixed that. Also moved the top right connectors up a little as they didn't line up with the STFM MB holes. The big keyboard post hole was a bit out also, so that should be fixed now.

q.jpg (318.25 KiB) Viewed 1364 times