exxos's Atari, Amiga & retro forum

Karl wrote: ↑Tue Jan 04, 2022 12:07 pm

terriblefire wrote: ↑Tue Jan 04, 2022 10:33 am You dont need better SDRAM. The SDRAM you have would work at 132Mhz no problems it just needs the timings padded.

SDRAM clocks arent the issue here. Its because the SDRAM is tuned to be at max performance on the timings at 50Mhz... Better SDRAM isnt any better here. You need to RTFM the timings your ram can do and alter sdram_defines.vinc

I already adjusted the timings for my current 66MHz board, but which SDRAM make/version is the 'Samsung B-die', so to speak?
I want to use the best components available If I decide to try higher than 66MHz.

I mean the Micron 166Mhz stuff is what i use. Its pretty pointless because the TF330 cant max the cheap stuff out.

@Karl Do you have a picture of this CPU ? I tried several from various sources years back and never found any really went over 55MHz (and even that was chronically unstable).

EDIT:

Tell a lie, 61.1MHz.

https://www.exxosforum.co.uk/forum/viewt ... mhz#p61350

I was able to run my CPU's on 60MHz on TF536, but had IDE problems. Picture of my cpu are here
https://www.exxosforum.co.uk/forum/viewtopic.php?t=3179
I finished LW3.5 render on it at 60MHz (34h)

I had tested many CPU's on TF536 and ACA1233. Only the real 50Mhz 1F91C was worknig ona ACA1233 at 50MHz and above 50mhz on TF536.

exxos wrote: ↑Tue Jan 04, 2022 2:39 pm @Karl Do you have a picture of this CPU ? I tried several from various sources years back and never found any really went over 55MHz (and even that was chronically unstable).

EDIT:

Tell a lie, 61.1MHz.

https://www.exxosforum.co.uk/forum/viewt ... mhz#p61350

The left CPU can do 66MHz @ 4.8V(early FW) I think. The CPU to the right cannot do 60MHz @ 5V. It's a lottery....


I've tested too few to be able to determine which mask is the best. I've found CPUs that can do 66MHz from both these masks.
The problem is finding a good supplier. Plenty of reprinted 030 CPUs these days. All the good ones I've found look worn like those in the pic.
It might not be the CPU failing. Most accelerator cards don't like overclocking.

terriblefire wrote: ↑Tue Jan 04, 2022 2:33 pm

Karl wrote: ↑Tue Jan 04, 2022 12:07 pm

I already adjusted the timings for my current 66MHz board, but which SDRAM make/version is the 'Samsung B-die', so to speak?
I want to use the best components available If I decide to try higher than 66MHz.

I mean the Micron 166Mhz stuff is what i use. Its pretty pointless because the TF330 cant max the cheap stuff out.

I actually don't need the fastest SDRAM. I want SDRAM that scales well with increased voltage and works well in a broad voltage range. The current SDRAM on my 66MHz board has narrow working range compared to what I used on a previous board.
The print is no longer visible on the better ram and the supplier has no more stock. Most top speed grades are fake here anyway. There are speed grades available that not even the manufacturer has.

As I'm no Verilog master and have no advanced test equipment, I do the following:

Fast RAM issues. Increase the 3.3 voltage.
IDE issues. Reduce the 3.3 voltage.

If I'm lucky I'll learn something. And if I'm even more lucky I can manage to modify the FW.
It can of course also be possible to find a voltage that makes all timings match, but not for 66MHz on my current setup.

Karl wrote: ↑Wed Jan 05, 2022 3:29 am
I actually don't need the fastest SDRAM. I want SDRAM that scales well with increased voltage and works well in a broad voltage range. The current SDRAM on my 66MHz board has narrow working range compared to what I used on a previous board.
The print is no longer visible on the better ram and the supplier has no more stock. Most top speed grades are fake here anyway. There are speed grades available that not even the manufacturer has.

What you're saying makes no sense. Scales in what sense. SDRAM performance is not governed by the voltage. Your limiting factor with this is the CAS Latency, CL count and initialisation timings.

The regulator on the TF330 doesnt power the CPU so all you're doing is killing the CPLD and RAM. Literally you're abusing your board really badly, it is probably going to go pop and then other people will try this. I'm inclined to nuke this thread before other people kill their TF doing what your doing.