Where to get 50ns 72-pin SIMMs?

[Oli_hd]

How "tall" are the modules?

31mm from top to bottom, about 22mm above the centre of the locking hole (the hole drilled in the simm)

but that is not the same thing as saying that the whole module can operate that fast. It does, however, mean that it will not be the chips that are the restriction.

The simm is made up from 16 chips, all rated at 50ns, there are no other components on the board (apart from surface mounted capacitors) but yeah, it could still be a 60ns simm

[Bamiga2002]

Bumping this topic here . I did some testing with different oscillators on my BPPC (normally 68060:50Mhz/PPC:60Mhz*4=240Mhz):

68060:66Mhz - tried to boot up and managed to load BlizKick, but at next boot stayed in an infinite boot loop for awhile, after which refused to boot at all. 3-finger salute doesn't help.

68060:60Mhz - seems to work steady with this speed. boots up and works fine.

PPC:66Mhz*4=264Mhz - PPC programs start but many times come the powerpc exceptions and the miggy hangs (mouse won't work). Not a good setting to use.

PPC:64Mhz*4=256Mhz - PPC programs start and...seem to work just fine! I'm using this now and looks good this far.


I thouht why some people seem to be able to clock their boards safely @66Mhz, still in my setup things crash and do not work if i set either the 68060 or PPC to 66Mhz bus speed. I didn't test the 68060 with 64Mhz (too lazy). But i think the overall stability comes from the 68060 and it's stability, so i won't up it's speed any further from 60Mhz (it's fast enough with that anyway :-)).

BUT, i also think the RAM quality/speed is to blame for not being able to run either the 68060 or PPC at 66Mhz. Next i'm going to hunt down some quality SIMMs that can cope with higher oscillator speeds. And YES, i have taken care of proper cooling on both 68060 and PPC :-).

Any experiences or solutions you lot might have as for what memory should work properly here?

[Oli_hd]

Good memory is always the key to overclocking, make sure your simms are 50ns, even if the chips say 50ns check the ident pins to see if they are telling the computer they are 50 or 60ns!

Other than that, what revision of 060 are you running? The current one is the fastest. (with the 71E41J mask)

Thats basically it for overclocking except stability is helped by upgrading the cooling/monitoring the temperatures.

[Bamiga2002]

WhichAmiga says:
MC68060 (rev 5)
PPC (rev 2.1) - it finds my 64Mhz oscillator at 63Mhz though :-)
My BPPC board is version 0.

[alexh]

Has anyone tried to use the CPU060 program that comes with Phase5 accelerators to change the WAIT_STATES of the RAM controller to increase stability at higher clock rates?

Of course this potentially has the ability to make the system run slower, but it would be good to test.

[stopthegop]

I have mine set as follows

68kwrite waitstate
68kread nowaitstate
ppcwrite nowaitstate
ppcread nowaitstate


If I try setting 68Kwrite to "nowaitstate" the system will crash midway through booting. I'm not sure why this is..?

[rkauer]

stopthegop wrote:
--zip--
If I try setting 68Kwrite to "nowaitstate" the system will crash midway through booting. I'm not sure why this is..?

 Because the RAM isn't fast enough. Simple, huh?

[Bamiga2002]

@Oli_hd
Checked closer the 68060 revision, it's 01G65E.

@alexh
Yep, what's the use of WAIT_STATES if they slow things down .

@stopthegop
Is there a reason for you using the CPU060 command (are you?), because you can set the RAM speeds in the BPPC-bootmenu?


I'm wondering what should be the middle route in options considering speed performance between overclocking and using RAM waitstates & preloads? If i overclock, in some point i have to slow down the RAM, so what's the use then? Btw. i have only activated PPC-precharges in the BPPC-bootmenu.

[alexh]

Bamiga2002 wrote:
@alexh
Yep, what's the use of WAIT_STATES if they slow things down .

In the situation where the CPU runs faster, the RAM runs slightly slower. Total system speed can be faster.

Dont forget the 060 will burst load it's caches and then run from cache at CPU speed. Some routines are optimised to fit entirely within the cache.

It's give and take, you'll just have to have a try.

[Bamiga2002]

@alexh
Maybe i'll test some more with the oscillators, fiddling with the waitstates etc. :-)

[Bamiga2002]

Bumping this thread here! :-)

I just ordered 2 pieces of 128mb SIMM-modules from Aememory, they are 60ns but no-go searching for 50ns 128mb ones. But i need the memory. And maybe i'll give up the overclocking if the memory can't cope...

I have to test and see :-P

Cheers!

[delshay]

see this tread about 50ns simms & Blizzard PPC (BETA)

http://www.amiga.org/forums/showthread.php?t=37475