I hope this isn't too much of a contravertial topic (I am blissfully ignorant of whether this is an approproate subject or not) but I'm hoping to clear up details surrounding modification of the aca1233n. Specifically replacing it's CPU of a different clock speed. (Of course I am aware it voids any warranty but I believe it is in the owners right to do whatever with hardware he owns, as long as it isn't copying it for resale etc)
On Amibay a person was selling a modified board with 50mhz CPU and fpu. You see, there are two Xtals, one regular one for the FPU (if added) and a SMD Xtal. According to the Amibay thread, this guy swapped the 80mhz Xtal for a 100mhz which clocked his 40mhz board to 50mhz.
http://www.amibay.com/showthread.php?99 ... t=aca1233n
But then on the icomp.de forum a customer asks if he is able to do this mod. He is told no as the Xtal is 80mhz for both the 26 and 40 MHz varient (he is initially unaware that his board is 40mhz but gets corrected by his board ID info) and the clock speeds are set via the CPLD. Which would require an expensive tuning by icomp."I replaced the SMD oscillator with a 100MHz one.. "
"I have DONE this to more than one board (In the past) and all work perfectly after CPU change (Cheap plastic CPU and NO MMU yuck).. But to do it, you need to use a solder pot to get the old CPU out in one piece (Solder temp setting must not be too high or the board will get burned)..... In the end a very nice board with a better processor fitted (In a socket now), AND it's a 50MHz processor with MMU (Not the 40MHz one without MMU)..."
https://forum.icomp.de/index.php?thread ... -or-50mhz/Question from customer on icomp.de forum:
I have ACA1233N 26mhz and I want to put faster CPU 40mhz or 50mhz. If I takeout this 68030 26mhz and I solder new 68030 40mhz or 50mhz, Ofcourse I swap crystal as well, will it work?
"No need to swap the Xtal; both the 26MHz and the 40MHz card use an 80MHz crystal. The CPU swap won't get you far; it will run at the exact same speed.""You can buy an updated CPLD for the difference in price of the two cards. That means: You ship the card to us with the new CPU on, we do the re-programming of the CPLD to 40MHz for 80,- EUR incl. VAT"
So from processing this information it seems:
If the 26 and 40 use the same Xtal and the clock divider is set in the CPLD, then the 50mhz varient (since the information was ommited by the icomp rep) probably does use 100mhz, changing the divider speed. But I am guessing that on a stock 50mhz board the CPLD would be updated to have its divider values updated for reference purposes in the ACATool app (where different divisions can be selected, for under clocking purposes only)
So I surmise that even though he was told no on the official forums, changing the Xtal to 100mhz would overclock any processor on the board, regardless of CPLD. This is assuming that britlord on the Amibay forums is telling the truth.
What do others think? Am I allowed to ask these questions, I am surprised that this isn't being asked anywhere on the internet in any Amiga forums, almost like big brother is watching...