exxos's Atari, Amiga & retro forum

Ok I have pretty much conclusively found why the 80Mhz limit is there on the TF1260 (at the moment). Its pretty simple really and most of you can measure it if you have one.

Basically the TF1260 existing firmware produces a 2x clock which is used to sample the 14mhz clock to recreate it.. I wont go into the details of why its got to be so fast but Nyquist etc.. The faster the sample the more faithful the clock reproduction will be.

Anyways. The CPLDs we have just crap out past 160Mhz and we stop getting a clock on the CPU line. There is a small resistor between the CPU and the CPLD on the top side of the board. You can measure CPU speed there. To test if this is happening simply probe that resistor after you set a high frequency and get a lock up. I usually 8 out of 10 times get no CPU clock.

The rest of the design works well past 80Mhz because ive had the TF4060 up at 100Mhz for extended periods. You dont need terminations or anything stupid like that because at 100Mhz everything is a terminator and being terminated fast. I actually do maths on stuff so i dont have to overengineer... but i usually measure for where there is a problem first.

Anyways the new TF1260 firmware will not have this limitation. It will not use a doubled clock and that in turn will give us more frequency steps.

We should now be able to get these steps

MULTIPLIER_4 // 100 Mhz
MULTIPLIER_3_75 // 93 mhz
MULTIPLIER_3_333 = //83 mhz
MULTIPLIER_3_2 // 80 mhz
MULTIPLIER_3_125 // 78Mhz
MULTIPLIER_3 // 75Mhz
MULTIPLIER_2_666 // 66Mhz
MULTIPLIER_2_5 // 62.6 Mhz
MULTIPLIER_2_4 // 60 Mhz
MULTIPLIER_2_333 // 58Mhz
MULTIPLIER_2 // 50mhz

Feel free to go measure the clocks at different speeds to see whats happening.

butbutbutbbtuu 106MHz?????!?!?!?!??? :-D

chucky wrote: 12 Aug 2021 09:39 butbutbutbbtuu 106MHz?????!?!?!?!??? :-D

Actually this makes me laugh a lot.... Especially when i see people earnestly discussing 106...

Google: "106 air do shocair" ... first hit.

Its an easter egg.

Hey what!?! Ludicrous speed is on the way!
Warp1260 will have to update their max :lol:

Going to be interesting to see if my factory 60Mhz full Rev 6 will do (currently installed on TF360) more than my 50Mhz.

Higgy wrote: 12 Aug 2021 12:22 Hey what!?! Ludicrous speed is on the way!
Warp1260 will have to update their max :lol:

Going to be interesting to see if my factory 60Mhz full Rev 6 will do (currently installed on TF360) more than my 50Mhz.

I have had Rev 4 LCs at 100Mhz in the TF4060. Rev 6s were less happy but i suspect its not got enough power to do the job at 100Mhz with the FPU

Wow, that's fantastic news! I've been playing through Doom (and installed Ultimate Doom, Doom 2, TNT, Plutonium pack etc etc). And by playing, I mean actually playing lol - I've got to level 6 and will continue later. It runs so bloody well on an LC CPU @ 62.5Mhz. (and I worked out how to enable music as well as sound - Paula rendition of the music is great, and worked out how to use the 060 for audio, and for C2P routines as well. It shifts!!)

I suspect I've been having the problem you are talking about here - it seems the clock disappears when switching to 75Mhz. Strangely I found it can be fine when the system is first powered on, but up to 2 mins. Then it goes...

This and the rest of what you're doing upgrading firmware just sound brilliant.

If it becomes possible to run my LC at more than 62.5 I'm going to need to do something about active cooling, haven't bothered so far but speed... :D

Superb!
:shock:

That's great news!

TF: Yay I got it running at x MHz!
Community: Yes but will it run at (x+2) MHz?

If it was me I'd limit it to 95 MHz and release a paid upgrade to 100 😂

dalek wrote: 12 Aug 2021 23:36 That's great news!

TF: Yay I got it running at x MHz!
Community: Yes but will it run at (x+2) MHz?

If it was me I'd limit it to 95 MHz and release a paid upgrade to 100 😂

Or little bit like car manufacturers, 3 tiers: basic - 50Mhz only, mid - up to 75Mhz, and premium all up to 100Mhz :D