exxos's Atari, Amiga & retro forum

I think the explanations for this have got lost in multiple threads . So I thought I would explain it all again in a new thread.

The original TF536 project did not cache ST-RAM. This was done deliberately to make the CPU basically run at the same speed as a 68000. But also it would malfunction horribly with DMA access because the CPU had no way to know when to invalidate the ST-ram caches.

In light of the cache issues, I patched TOS206 to include the TOS306 cache control routines which dealt with the 030 cache correctly. It basically fixed the DMA and other weird cache related problems.

The current release version of the ST536 firmware does not cache ST-RAM. It is still unknown about compatibility issues in this respect. However, the experimental firmware also caches ST-RAM.


Last year I used frontbench to test the caches. IIRC, there was absolutely no difference between ST cache only or TTram cache only. The scores ended up basically the same.

The problem being when we cache STram, we speed up the ST-RAM stuff a bit, but then starve TTram of it cache. So if running frontbench in TTram, you lose the cache hits to TTram. The same in reverse, that if you run TTram cache only, you sacrifice the STram cache speeds. The whole point of the experiment was to see if enabling ST-ram would work better than using the cache with TTram only. But the results were surprising and disappointing.

Now the experimental firmware enables ST & TT ram cache. Though to my knowledge nobody has done any tests between the 2 methods. I am basically assuming that if you are running in STram *or* TTram then the CPU cache would favor the relevant RAM more. However when enabling ST & TTram cache, you are basically trying to cache more RAM, so it increases the likelihood of cache misses, which can then overall make the system run slower.

So there are basically three methods of using the cache.

ST-RAM cache only - No firmware.
TT-RAM cache only - Release firmware.
ST & TT RAM cache - Experimental firmware.

In any scenario you need my patched TOS206 to work properly with the 030 CPU (or EMUTOS) .

Later firmware used what I dubbed "slow ROM". Originally I had used the normal 55ns ROMs and run them at maximum speed for ROM access. Though people requested the ability to use the 100ns EPROMS. So I deliberately slowed down the ROM access to allow that and abandon the "Fast ROM" code brach. Fast-ROM was not really needed because people should be using MAPROM which copies TOS to TTram which runs faster than the actual ROM anyway.

ACSI wire for IDE AUTOBOOT - This was also deemed obsolete in the latest versions of the firmware. It went on pin 10 of the ACSI port to allow IDE autobooting (INTR). Connecting this wire will likely cause malfunctions with the latest firmware as I believe I used the same pin as a debug output at some point and never removed the code. So under no circumstances connect this wire with the latest firmware! The interrupt is now emulated within the firmware.

Also I should stress (again) that the blitter cannot be used with TTram. This is why you should use NVDI (or remove the blitter). This does not mean the ST536 is not compatible with the blitter. You can still run games which use the blitter providing you are only running them from STram.

I also need to stress that there are many versions of MAPROM floating about and you should always use the ones in the official release files. I'm not able to compile or edit MAPROM myself in the later builds. Indeed later versions (if any) than in my release files are assumed to be experimental and untested. I'm assuming nobody is actively maintaining MAPROM anymore. I'm not aware of any issues with the released build anyway.

I also need to point out that my build of TOS206 (english) was thoroughly tested by myself and it was the other language versions which I have not tested. Though I did make some changes from the english only version, but I think this was just adding some debug type messes on TOS startup just to indicate what it was initialising during boot up. I think I may have also fixed some weird RAM problems as well.

There seems to be some confusion over the ST536 ROM.

My patched version of 206 is a proper cached fixe version for the 030 CPU. Original TOS206 is built for the 68000 and has issues with the dma system etc. So you should never use original TOS206 with anything but a 68000.

The patched TOS206 on the ST536 page is the one you need and have to burn yourself as I don't sell it in the store.. why you ask ? Because currently there isn't anything to flash in bank 2. So it's a bit of a waste of a ROM .

While I had issues with EMUTOS originally , In the end I focused on TOS due to lack of time. EMUTOS may or may not work but nobody has done any amount of testing and there are no active maintainers of MAPROM which may have been conflicting with EMUTOS. If there are issues with EMUTOS then I'm afraid I don't know how to fix them. You will have to take it up with their dev team. I can't fix MAPROM or EMUTOS myself. I really struggled to figure out how to patch TOS and complile it.

Plus with EMUTOS being updated often, my ROMs would always be out of date. Plus every version would have to be reverified before being burnt onto a ROM. It's just all time I unfortunately don't have. There unfortunately isn't likely to be any testers and maintainers for it all. So I have to state EMUTOS isn't tested and not supported at this point in time.

So overall. It's just better for people to burn their own ROM. Use my build of 206 as there are no known issues. Give EMUTOS a try but I can't offer support for that personally.

Hi All,

I've just built us a TF536 that I received from EXXOS a month or so ago. I'm trying to get it to run in a MEGA 4. I've managed to program the CPLD a number of times but no matter what firmware I load up the ST either boots to a blank grey screen or a bombed screen and then reboots.

I've attached some pics off the completed board. Note that this is the Amiga version of the board but I think I read somewhere these will work in an ST with the right (developmental) firmware loaded?

Any help appreciate.

Thanks

Sonny

Your trying to run a Amiga TF536 with the Atari ST536 firmware.Totally different projects and not compatible. The TF536 doesn't even have ROM for starters. You have built the wrong board.

The ST536 firmware is not compatible with the TF536. There's TF536 firmware from somewhere for the ST but you still need ROM and that that's as all abandoned years ago and not one of my projects. I've explained all this a million times already..

https://exxosforum.co.uk/atari/last/TF536/index.htm

You might get some help from @PhilC for getting the original tf536 board programmed and working for use in an ST

(I bought one off hi a few years ago & IIRC he'd built a few others for himself & other forum members as well)

So it is possible but the ST536 gives more overall performance in an ST.

HTH

Thanks for the tip. I've messaged @PhilC so hoping he can guide me on how he got the cards working.

Hi All,

So there is good news and bad news.

The good news is that @PhilC got back to me and let me know there is indeed a firmware version for the TF536 boards that will allow it to work with a ST and EmuTOS. That's good news indeed.

The bad news is that he had a hard drive failure and lost the firmware I need. He suggested I ask on the forums.

So, does anyone have the original TF536 firmware that PhilC developed and they are willing to share with me please?

Thanks

Sonny

@macsonny

You probably want to read through this entire thread. It was so long since I touched my ST with TF536 that I can't remember the details: viewtopic.php?t=3442

My own ST was running the latest experimental stuff that has support for ST-RAM caching, which can make things go very-fast(tm)
I think the link at the bottom of this page was the last released binary.
viewtopic.php?t=3442&start=100

You may want to grab the support tools directly from the github page as I don't think the posted zip would contain the FPU emulator which is also quite handy to have.

This page demonstrates the difference in speed when running st-ram stuff:
viewtopic.php?t=3442&start=70

However, enabling L1 and/or L2 caching of ST-RAM _could_ introduce issues with DMA.
There is a setting in the config file to enable fixes for that but may or may not be foolproof for everything.
I do remember being able to run stuff off the Gotek on my ST with L1+L2 st-ram caching enabled, and with the highest dma-fix setting. Make sure to read maprom.txt for info.


If you rather use an older firmware before any of the crazy experiments started you should be able to find those in the thread too. Perhaps tf536_2020_10_04_ATARI_alpha.zip is the last one before that stuff? I don't remember :)

The maprom and tools on github are the rewritten stuff that adds support for the new experimental things.
If you rather want the pre-rewrite maprom then I'm sure there are binaries in the thread too (source for the old version is on github but the pre-compiled binary is only for the latest)

Thanks!

I'll let you know how I go!