PAK 68/3 in STE

[HigashiJun]

I'm on a new project and I've tried to fit (temporarily for the moment) my PAK68 in my STE.

Everything runs smooth when the PAK is in the fallback 8Mhz mode, but the STE doesn't go past the memory test (sometimes it does with the help of the reset button, and I have a full working desktop under TOS 3.06).

I have non-parity RAM at 70ns, so it should not be a problem for the PAK.

I had no time to investigate further but if you have any ideas, it would be great.

Cheers.

[Darklord]

When you say "fallback 8mhz mode" are you referring to using a 68k CPU on the PAK board itself,
or the "test" mode where you change a few jumpers on the Pak board? (I didn't think that mode
ran in 8mhz but it might).

Thanks.

[frank.lukas]

With my Mega STE it works not without a PuPla/2 but in a normal STE it should work without.

The Pullups in my Mega STE are all original and not low as exxos recommends ...

nt_fertig_rohaufbau.jpg (280.35 KiB) Viewed 2228 times

[HigashiJun]

When you say "fallback 8mhz mode" are you referring to using a 68k CPU on the PAK board itself,
or the "test" mode where you change a few jumpers on the Pak board? (I didn't think that mode
ran in 8mhz but it might).

Thanks.

Yes, there is a 68k CPU on the PAK itself.

[HigashiJun]

With my Mega STE it works not without a PuPla/2 but in a normal STE it should work without.

The Pullups in my Mega STE are all original and not low as exxos recommends ...


nt_fertig_rohaufbau.jpg

I had 2.2K pull-ups in my Mega ST and the PAK68 was rock stable at 40Mhz, despite the Mega ST is known to have bus issues.

My RAM problem is identical to the one exxos is mentioning in this post (see the memory test pics):

https://exxosforum.co.uk/forum/viewtopi ... start=2280

I first thought there was a connection problem between the CPU socket and the adapter, but I should also have issues in the 8Mhz fallback mode, while it's not the case.

[HigashiJun]

Ok, time went by but my project was not abandoned but just pending for a while...

Thanks to @frank.lukas , I could build my Pupla/2 (many thanks again, Frank ! ):

Pupla2.JPG (421.1 KiB) Viewed 2082 times

For those who remember one of my (old) previous thread, I also have a PUSTE, but it's not very convenient for the STE and I would have to cut its PCB a bit to let it fit correctly in the machine, something I don't want to do 'cause these gimmicks are very rare and I don't feel like butchering one just for the sake of testing. That said, PUPLA/2s are better then PUSTEs, and it would be not worth fitting something "deprecated".

I also had to fit a 68 Ohm resistor on pin 20 of GAL U1 on the PAK, which will then have to connect to one of the PUPLA's header pins.

PAK68.JPG (490.33 KiB) Viewed 2082 times

If time allows today, I will test this setting and check if memory errors still occur.

[exxos]

The Pullups in my Mega STE are all original and not low as exxos recommends ...

Good. Because I never recommended changing them in the MSTE. But with so many TTL chips hacked on , they have internal pullups on their inputs. So you have lowered the value anyway.

[frank.lukas]

2,2k Pullups are far too low for the PAK ...

[exxos]

My RAM problem is identical to the one exxos is mentioning in this post (see the memory test pics):

https://exxosforum.co.uk/forum/viewtopi ... start=2280

I first thought there was a connection problem between the CPU socket and the adapter, but I should also have issues in the 8Mhz fallback mode, while it's not the case.

Mostly that was noise on the RAM bus causing issues on the Falcon. Not so simple to fix.

Though the STE is very bad with the 8MHz clock. I had no end of issues with my V1 series STE booster. I had to put a buffer on it in the end to solve the problems. But I never got my PAK (also built by frank) to work in any of my machines. Modded or not. I gave up in the end and invested in the TF536 project which works perfectly on the STFM,STE,H4,H5. I am also designing a dedicated STE variation as well.

[HigashiJun]

My RAM problem is identical to the one exxos is mentioning in this post (see the memory test pics):

https://exxosforum.co.uk/forum/viewtopi ... start=2280

I first thought there was a connection problem between the CPU socket and the adapter, but I should also have issues in the 8Mhz fallback mode, while it's not the case.

Mostly that was noise on the RAM bus causing issues on the Falcon. Not so simple to fix.

Though the STE is very bad with the 8MHz clock. I had no end of issues with my V1 series STE booster. I had to put a buffer on it in the end to solve the problems. But I never got my PAK (also built by frank) to work in any of my machines. Modded or not. I gave up in the end and invested in the TF536 project which works perfectly on the STFM,STE,H4,H5. I am also designing a dedicated STE variation as well.

That's quite weird as they (WRS online) say the PAK is a very stable device. Maybe it's very stable once you get it to work...

Good news for the STE version of the TF536. The only con of this device is the lack of FPU (only a personal thought though).