exxos's Atari, Amiga & retro forum

@TotO Just looking at that 330pF capacitor, its C5 on the original, but locating it on the PCB.. the mouse jumps in between the FPU and CPU, but there is no capacitor there :shrug:

EDIT:

OK so the mouse wrap doesn't work correctly. The capacitor is under the CPU.


I say its a copy/paste error.

As expected it is a little schematic error. Anyway, I have already replaced them and added more capacitors to the VCC pins.

Looking good :thumbup:

@TotO

Capactiors: they're a bit of a mess there, to be honest. @exxos and I have been talking about bypass caps in general and they do need an overhaul. More capacitors in general around the CPU & FPU.

The values I probably cribbed from somewhere, the spread, 10u, 100n and 330p is not unreasonable from a transient suppression point of view, but in reality I probably only used three 10us: one for the CPU, one for the FPU, one for the regulator. The rest were 100n, I think.

I'm afraid I tend to that -- just put down caps on the schematic and either not rate them at all, or rate them incorrectly. :lol:

I suspect C16 was meant to be a CPU capacitor but got re-numbered in an automatic board re-annotation. Sorry about that.

MMUDIS and CDIS pulled high is the normal state of affairs.

Speeds there's no speed-up accessing the Falcon's motherboard resources as those are regulated by the 16MHz clock.

Good luck!

BW

Thank you! :D

A little update with more decoupling capacitors for the RAM circuits. (the forum looks to compress the picture)

Really looking forward to seeing it boot up :)

Currently, I have one problem, but not with the PCB: I can't run Xilinx ISE with Windows 11 on my computer.
The installer fail, I can't properly install the software. Some forums report this issue and no solution exist.

May be someone can let me know currently how "full" is the XC95288XL design?
Because the FPU was dropped and I would like 16MB TT-RAM, may be a XC95144XL is enough?

TotO wrote: 02 May 2023 12:07 May be someone can let me know currently how "full" is the XC95288XL design?
Because the FPU was dropped and I would like 16MB TT-RAM, may be a XC95144XL is enough?

I remember talking to @Badwolf about using the smaller PLD previously and is not really possible to fit :( I would think just the FPU decoding line would not significantly impact anything anyway. I think it's the SDRAM code which takes up the bulk of the room. As you probably know the 288 is rather expensive :(


EDIT:

:WTF:


Am I going mad I could have sworn it was a 288 ?? I remember having the conversations with @Badwolf About doing a cutdown version to use the cheaper PLD at some point... :stars:

I downloaded from the git and tried again..