exxos's Atari, Amiga & retro forum

It's great to see you back at work again, doing some good old boostin'. :lol:

This pushing up of clock speed does interest me...

I wonder how much faster this CPU package type of the 68k can reach (with all the capacitance/interfacing signal problems sorted, so it's just the limitations of the CPU itself manifesting) using progressively more extreme active cooling solutions and a nice dose of overvoltage?

Can't wait to see how far you get with this. Keep up the great work! :dualthumbup:

mrbombermillzy wrote: 22 Mar 2022 14:37 It's great to see you back at work again, doing some good old boostin'. :lol:

:) Yeah not "back" by far yet. Just doing a bit of pottering about now and then currently. It might even be next year before I get back to things "full time". Just got too much stuff to get done currently.

mrbombermillzy wrote: 22 Mar 2022 14:37 I wonder how much faster this CPU package type of the 68k can reach (with all the capacitance/interfacing signal problems sorted, so it's just the limitations of the CPU itself manifesting) using progressively more extreme active cooling solutions and a nice dose of overvoltage?

Can't wait to see how far you get with this. Keep up the great work! :dualthumbup:

If I run it at 5.2V then 64MHz runs at full speed. But it is not a great solution really. I don't think the CPU is overheating because even running at higher voltages, it can get rather hot, but still does not crash. I suspect the actual CPU die is running like 30c hotter than the package. It is certainly not "burn your finger hot" . But obviously not a good way of running things. Which is why I need to solve the parasitic problem as it will inherently run a lot cooler anyway.

I had not considered when I designed the system that while the RAM is 10ns, the bus takes at least 20ns to actually settle.. Then plus the 10ns delay of the RAM.. PLD delays etc.. It all adds up.. The system will run perfectly happy at 50MHz. but I'm hitting a brick wall of limitations that 64MHz could take some time to resolve. Wherever the limit lies, I think 80Mhz is going to be the literal ceiling on this. Of course I want to push it as much as I can just out of pure interest more than anything :)

exxos wrote: 22 Mar 2022 14:58 :) Yeah not "back" by far yet. Just doing a bit of pottering about now and then currently. It might even be next year before I get back to things "full time". Just got too much stuff to get done currently.

Well, you just ease in at your own pace.

I think @rubber_jonnie seems to be doing a good job running the forum; well, filling the forum with posts anyway! :lol: :poke:

Will be keeping a close eye on the work done here though. ;)

This is an incredible project! How compatible is this "SEC" vs a stock 68K?

GadgetUK164 wrote: 22 Mar 2022 20:13 This is an incredible project! How compatible is this "SEC" vs a stock 68K?

All I can find is this on wiki.. Whatever it means.

The 68000 does not meet the Popek and Goldberg virtualization requirements for full processor virtualization because it has a single unprivileged instruction, "MOVE from SR", which allows user-mode software read-only access to a small amount of privileged state. The 68EC000 and 68SEC000, which are later derivatives of the 68000, do meet the requirements as the "MOVE from SR" instruction is privileged. The same change was introduced on the 68010 and later CPUs.

IIRC the SEC was supposed to be 100% code compatible, but wiki says otherwise :shrug:

As to how important that is, whos knows ? But the 030 is a lot different and people seem to manage fine with that one.

mrbombermillzy wrote: 22 Mar 2022 18:04
I think @rubber_jonnie seems to be doing a good job running the forum; well, filling the forum with posts anyway! :lol: :poke:

Thanks for the (Back handed) compliment. I think....

rubber_jonnie wrote: 22 Mar 2022 22:39

mrbombermillzy wrote: 22 Mar 2022 18:04
I think @rubber_jonnie seems to be doing a good job running the forum; well, filling the forum with posts anyway! :lol: :poke:

Thanks for the (Back handed) compliment. I think....

At least he's not trying to provoke you into more purchases...with this post anyway! ;)

JezC wrote: 22 Mar 2022 22:41

rubber_jonnie wrote: 22 Mar 2022 22:39

Thanks for the (Back handed) compliment. I think....

At least he's not trying to provoke you into more purchases...with this post anyway! ;)

Honestly, I don't need provoking!!

rubber_jonnie wrote: 22 Mar 2022 22:41 Honestly, I don't need provoking!!

:lol:

No fair I wanna play with a ram board too :lol:

My sec ran everything I tried it on, although it was only running at 64mhz not 80 like @exxos's one.

I have a spare water cooler setup handy. 100mhz anyone? :lol: