exxos's Atari, Amiga & retro forum

I know you're not one for feature-creep, but the 680x0 line has supported a level 2 cache since the 68030. Add a healthy 256KB cache with some wait states when having to hit SDRAM. Slower SDRAM access should allow higher clocks and cache should greatly improve performance over even fictional single-cycle SDRAM. You just need a tiny bit of extra logic and some really fast SRAM -- and today, that's not much of a problem. DigiKey has 256x36b SRAM that are 3ns and 200MHz for under $6.

renee.cousins wrote: 06 Sep 2019 04:36 I know you're not one for feature-creep, but the 680x0 line has supported a level 2 cache since the 68030. Add a healthy 256KB cache with some wait states when having to hit SDRAM. Slower SDRAM access should allow higher clocks and cache should greatly improve performance over even fictional single-cycle SDRAM. You just need a tiny bit of extra logic and some really fast SRAM -- and today, that's not much of a problem. DigiKey has 256x36b SRAM that are 3ns and 200MHz for under $6.

Erm. this doesnt make sense.

1. The SDRAM can be accessed in burst mode. The 060 can access a line at a time 3 + 1 + 1 + 1... ( and i rekon i could make it go faster).
2. The SDRAM can do 170Mhz and the CPU craps out at 110Mhz.
3. The 060 already has a buttload of cache.

It would make more sense to buffer 400Mhz DDR ram in a tiny fifo than your suggestion.

EDIT: I guess I’m utterly confused why the cpu speed is perceived to be limited by the SDRAM. It’s not.

I built my 360 last night.
I bought a 1.5A voltage regulator with non matching pinout so I had to build this contraption to connect it. Even so, it gets super hot. Not sure if it should be cooled...

At first I couldn’t get it to boot since I was trying this EC CPU. I didn’t realize it wouldn’t work: Now I’ve fitted it with a full rev 1 and it’s working nicely at 50 MHz. I need to create an appropriate CF card setup with 060 software before I can do more experiments.

Time is tight now that wife has gone back to full
Time work and kids require lots of attention... but I’ll do what I can :)

EC versoins doesn't have MMU nor FPU, hence it will not work :!:
LC's should work

EC works on the A3660.

alenppc wrote: 08 Sep 2019 14:41 EC works on the A3660.

yes, it does work on A3660, but not on TF360, cause Stephen implemented FPU disabling in CPLD

EC doesn't need patched ROMs to disable FPU on A4000

alenppc wrote: 08 Sep 2019 14:41 EC works on the A3660.

Not very well and probably only with caches off. Without the MMU you cannot set the cachability of memory regions.

terriblefire wrote: 08 Sep 2019 14:58

alenppc wrote: 08 Sep 2019 14:41 EC works on the A3660.

Not very well and probably only with caches off. Without the MMU you cannot set the cachability of memory regions.

Never had issues on that particular card and I run it for a while on the A4000, caches on and everything. I am NOT saying that we should leave this as an option for the 360 I just didn’t realize it would cause boot issues on it, that’s all.

terriblefire wrote: 08 Sep 2019 14:58

alenppc wrote: 08 Sep 2019 14:41 EC works on the A3660.

Not very well and probably only with caches off. Without the MMU you cannot set the cachability of memory regions.

Thats absolutely correct, most programs expect MMU (and FPU) as soon as 060 CPU is detected

alenppc wrote: 08 Sep 2019 15:03

terriblefire wrote: 08 Sep 2019 14:58

Not very well and probably only with caches off. Without the MMU you cannot set the cachability of memory regions.

Never had issues on that particular card and I run it for a while on the A4000, caches on and everything. I am NOT saying that we should leave this as an option for the 360 I just didn’t realize it would cause boot issues on it, that’s all.

I actually dont know why the EC woudnt start on DiagROM... maybe it was just unhappy at 50Mhz.