exxos's Atari, Amiga & retro forum

I have not mentioned this project before publicly but it has been ongoing in the background for some time now.

Before anyone gets excited, no you can't "have one to try" yet as I only literally just got the stock thing booting up! and no, I haven't tried this or that or IDE or anything other than shown GB6 of it running initial firmware. This is a "stepping stone" board as for starters, I have no idea how to use or xlinix stuff. So it will take me a while to get to grips with.

This board was designed for the ST only and will not work on Amiga's. Any existing firmware will not work on this board. I decided to start over with the firmware (at least based on original sources by TF and fixes by agranlund) . I wanted to get to the bottom of all these odd firmware and hardware issues, so I literally have to start from the "ground up" in order to figure out what's going on.

As people can see, there is now a ROM on board. When I figure it out, It can hold TOS206 / EMUTOS and decoding is done on the TF536r3! So in terms of H5 users, you can just plug it in like I did and away you go. Though as original machines are just not stable enough, I am not spending time hunting down problems why it doesn't work on those machines either.

My current aims are to get ROM decoding working, and optimise the firmware where possible. Though as I am swamped with work currently, I cannot say when this will get done. But it is on my "to do list" at least and there has been some good progress already this morning!

Sweet! 8-)

If you need any testing in the future with this in the H4/H5 against a stock TF536 with ST firmware, let me know!

Would be happy to help support this effort any way I can.

Nice!

Apparently @exxos will design the ST as it should have been from day 1 :)

Keep wondering though why you didn't opt for the STE features on H5s.

MegaSTEarian wrote: 01 Mar 2021 12:28 Keep wondering though why you didn't opt for the STE features on H5s.

How? when its a ST chipset ? I think you missed a lot of posts about all that.. Of course you can't re-use STE parts so easily like STFM's. STE's are harder to find, more expensive, more work. Important thing was to actually get a stock system working reliably first, then build on it.

Now, if that 68030 could be moved to the other side of the board... ;-)

Hehe.

Anyway, it's good to see that development is continuing. Just out of interest, will the ROM interface 512K ROMs as well as twin 256K ones?

stephen_usher wrote: 01 Mar 2021 13:05 Anyway, it's good to see that development is continuing. Just out of interest, will the ROM interface 512K ROMs as well as twin 256K ones?

Bank select is done via jumper.. One of the main problems is there are no free IO lines on the PLD.. It's why I had to re-design a chunk of it just to break out the ROM enable line & HDD IRQ (which were basically sacrificed from higher RAM address lines) ... So in theory it can be done, physically be able to do is another matter.

But really it would just be better to boot from TOS206 or whatever in ROM, then load TOS into fast-ram.. As the ROM itself can't run anywhere near the speed that alt-ram can in 32bit RAM @50Mhz. So I think the onboard ROM should really be treated as a "Boot ROM" if anything.

exxos wrote: 01 Mar 2021 12:46

MegaSTEarian wrote: 01 Mar 2021 12:28 Keep wondering though why you didn't opt for the STE features on H5s.

How? when its a ST chipset ? I think you missed a lot of posts about all that.. Of course you can't re-use STE parts so easily like STFM's. STE's are harder to find, more expensive, more work. Important thing was to actually get a stock system working reliably first, then build on it.

I did miss a lot about it but I thought that although STE is a tad more complex than ST, it would be fairly easy to replicate in the new boards (the additions would be the extended features but I cannot tell what that actually means in terms of hardware, tbh).

exxos wrote: 01 Mar 2021 13:16

stephen_usher wrote: 01 Mar 2021 13:05 Anyway, it's good to see that development is continuing. Just out of interest, will the ROM interface 512K ROMs as well as twin 256K ones?

Bank select is done via jumper.. One of the main problems is there are no free IO lines on the PLD.. It's why I had to re-design a chunk of it just to break out the ROM enable line & HDD IRQ (which were basically sacrificed from higher RAM address lines) ... So in theory it can be done, physically be able to do is another matter.

But really it would just be better to boot from TOS206 or whatever in ROM, then load TOS into fast-ram.. As the ROM itself can't run anywhere near the speed that alt-ram can in 32bit RAM @50Mhz. So I think the onboard ROM should really be treated as a "Boot ROM" if anything.

The alternative would be to add separate logic for the ROM decode which connects only to the high address lines, /ROM, /AS and /RW plus output for DTACK, A1-A17 going directly to the ROM physical switches. This would mean not having to mess with the PLD at all.

As for the ROM speed, that's fine, just put ROMSPEED or MAPROM into the AUTO folder and the job's a good-un.

MegaSTEarian wrote: 01 Mar 2021 15:50 I did miss a lot about it but I thought that although STE is a tad more complex than ST, it would be fairly easy to replicate in the new boards (the additions would be the extended features but I cannot tell what that actually means in terms of hardware, tbh).

Instead of having a couple of PLCC68 chips, you have this to contend a large SMT IC for starters. As original chips are re-used. We are not replicating anything chipset wise (yet) . I would suggest you have a read through the remake section and see whats being done any why on all these boards.

@exxos that looks familiar?