Potential changes on a future board.

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exxos
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Potential changes on a future board.

Post by exxos »

I have mentioned a lot of this previously but not had much feedback about any of it yet..


CAPACITORS
I am still in two minds about this..Would we stick to the leaded ones, or go with SMT next time ?
It is actually possible the large 100uF SMT caps may not even be needed.


RAM
Would we keep the Falcon RAM board on the next revision ?

I'm also thinking about a smaller plug in RAM board as mentioned here https://www.exxosforum.co.uk/forum/viewt ... =13&t=2356 Where the RAM board could actually double up for the Acorn computers. Mostly the 72pinn simm is probably the best option to keep.. or not ?

I am not wanting to solder any RAM to the motherboard, As people should know by now, if the RAM goes faulty and is soldered down, they can turn into a mini nightmare, in particular if that DRAM chip is no longer obtainable.

I have seen some large DRAM (again used on the Acorn memory boards) chips where they can be socketed..
ZT-SOJ-4-40.jpg
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But again, if these chips on a longer obtainable, and that is the only memory solution on the board... This is why I think some sort of pluggable solution is always the best option, the problem being I don't want to really create a custom board like the Acorn unless they are worthwhile to do so, hence a "second market" for the boards.

In relation to the SIMM socket, because these sockets are expensive, it will be better to try and not use them, but then again, creating a custom board to replace it is going to be more expensive than a custom RAM solution anyway.

It may be better for me to look into producing 4MB 72pin simms instead. if I went down that route, I could design my own simm and even have a simple row of header pins on the top of the board where it could be soldered directly into the motherboard without the socket. And it could still be used as a regular simm anyway.

I was talking to Icky about this a few days ago, where we was thinking about using more modern socket if we were to create a new sim. With more pins we could even add alt-ram onto a "super simm". But this would have course make this simm rather expensive. And it is still possible whatever socket we decide on, may not be on the market for long anyway. It is why I think just using header pins as much is possible is the way to go because headers don't generally vanish off the market and they are low-cost as well.


JUMPERS
We have a hell of a lot on this current board. But this is because it is a develop machine for any possible future FPGA boards. but technically if a revised motherboard was done, it would not necessarily need all the jumpers as it would be a more "final release board" than a "development board". We could go back to the solder blob jumpers for the blitter etc as well if people think that would be better.


OTHER STUFF
I don't know if anyone else has any suggestions for minor tweaks ? The only thing which I noticed was maybe moving the main OSC away from under the PSU may be beneficial? or any suggestions people may have in order to reduce parts costs for assembly time etc.

Also as mentioned in this thread.. https://www.exxosforum.co.uk/forum/viewt ... =73&t=2231 About potential low-cost versions of assembled boards.

I will probably keep the SMT GLUE & MMU for the final H4 release board. I would really want to remove these and even rearrange where the chips are located on the motherboard as well. Though this would mean I would need to reroute a lot of the board again which I am not really sure its worth it.


LONG TERM
As to if a final H4 board is released or not depends on demand from the community. I do still have several H4E boards to sell yet, these will likely appear in my store after Christmas.

Over the coming year work will continue and hopefully finish on all the projects myself and Icky have been working on lately, like IDE & flashy etc. Once all these designs are finished and tested, I would look to integrate them on a new series of motherboard.

We also have the FPGA stuff to do something with, so likely this you will keep us busy for a long time. But basically as mentioned in the "Future of the project" link above, if we go FPGA, we are actually wandering away from a legacy machine which is what the "H series" of boards are. So likely once all kits have been integrated onto that series, we can finally call that series of motherboard completed and future development would be towards a more FPGA based machine.
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TimNaber
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Re: Potential changes on a future board.

Post by TimNaber »

My thoughts:

RAM: I think anything that can or may need to be replaced in the future should never be soldered. The biggest items that fall into this category are memory and custom chips. Please do not solder the memory down. The extra money for a socket is worth it.

Jumpers: Should keep the ones that enable or disable standard items, like Blitter, unless TOS can determine if they are present or not, automatically.

Other: Socketed custom chips are better than SMT for replacement purposes for people whose soldering skills are beginner to moderate.

Long Term: Once items like IDE and Flashy are integrated and board is fully debugged, keep that board as is, even produce it unpopulated on an ongoing basis if you do not want to build up the boards. I am sure there are those that will buy the board and populate it to sell complete. Then, move to the FPGA computer as a separate item, producing both. I am sure there are those like me that do not have an interest in an FPGA computer and the availability of the remake board is perfect.
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Re: Potential changes on a future board.

Post by exxos »

TimNaber wrote: Thu Dec 05, 2019 3:48 pm RAM: I think anything that can or may need to be replaced in the future should never be soldered. The biggest items that fall into this category are memory and custom chips. Please do not solder the memory down. The extra money for a socket is worth it.
RAM wont ever be soldered down no.
TimNaber wrote: Thu Dec 05, 2019 3:48 pm Jumpers: Should keep the ones that enable or disable standard items, like Blitter, unless TOS can determine if they are present or not, automatically.
The bulk of the jumpers is around the ROM area. They are for future FPGA boards, but they are not needed to "set" anything. Its more those than anything.

TimNaber wrote: Thu Dec 05, 2019 3:48 pm Long Term: Once items like IDE and Flashy are integrated and board is fully debugged, keep that board as is, even produce it unpopulated on an ongoing basis if you do not want to build up the boards. I am sure there are those that will buy the board and populate it to sell complete. Then, move to the FPGA computer as a separate item, producing both. I am sure there are those like me that do not have an interest in an FPGA computer and the availability of the remake board is perfect.
That's what I talk about in the other thread. I really would prefer someone else taking over sales of these boards, and even assembling them if they wanted to sell them on etc. its just things I don't have time to do at the moment.
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Re: Potential changes on a future board.

Post by exxos »

One thing I totally forgot about.. Was I planned to have a DC jack on the back somewhere to power external devices like Ultrasatan without needed a additional external PSU.

I guess I could add a DC jack or USB jack, or both ?
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viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
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Re: Potential changes on a future board.

Post by derkom »

exxos wrote: Sun Dec 15, 2019 1:45 pm I guess I could add a DC jack or USB jack, or both ?
I don't know how much enhancement hardware you want to put on the main board, as opposed to plug-in upgrades, but how about including Lightning-compatible USB in the design, and giving it an external, powered port?
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Re: Potential changes on a future board.

Post by PaulJ »

My thoughts on H4+ versions.

I believe the only solution is the simm. The Falcon memory card is totally redundant. I purchased one from Harry for the remake board. It has a simm socket so all those connections to plug the board in are totally redundant and just possible bad connections.
-
Heres a thought that I haven't investigated so see what you think. ASSUMPTIONS: When the Icky clock doubler board is installed most things are run at 2x the normal clock, cpu, memory. I assume refresh is also running at 2x. (assumption). If this is true could we not add a address to the simm to refresh the next 4 meg on every other refresh occurance. If my assumptions are correct could we get some extended memory easily?
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I believe I would vote agains the SMT glue and emu. For trouble shooting it can suck to have those devices soldered on. I am building the second H4 with the SMT devices so I could have a change of heart but I doubt it.
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I would be ok with SMT caps. I do have a lot of through hole caps but I would prefer SMT devices, also doesn't SMT free up some board real-estate when routing the board. Bottom line is I can live with either.
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I prefer the jumpers. It provides a level of flexibility not available on a board without jumpers.
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A connector that would allow a NOVA capable connection to add a ISA video card.

My two cents.. :ball: :headbang: :ball:
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Re: Potential changes on a future board.

Post by exxos »

derkom wrote: Sun Dec 15, 2019 2:34 pm I don't know how much enhancement hardware you want to put on the main board, as opposed to plug-in upgrades, but how about including Lightning-compatible USB in the design, and giving it an external, powered port?
Not sure I understand what your getting at there.. Lightning I know nothing about or USB, so I can't including it on anything relating to the H4 past what they have already developed which is just a plug in board on the CPU.
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Re: Potential changes on a future board.

Post by exxos »

PaulJ wrote: Sun Dec 15, 2019 2:41 pm I believe the only solution is the simm. The Falcon memory card is totally redundant. I purchased one from Harry for the remake board. It has a simm socket so all those connections to plug the board in are totally redundant and just possible bad connections.
The Falcon RAM board may be removed in future revisions.

PaulJ wrote: Sun Dec 15, 2019 2:41 pm Heres a thought that I haven't investigated so see what you think. ASSUMPTIONS: When the Icky clock doubler board is installed most things are run at 2x the normal clock, cpu, memory. I assume refresh is also running at 2x.
We haven't got anywhere near 16MHz mods yet. I need to solve the wake up state sync problem yet, I designed the board but haven't had time to work on it for some months now. As to if 16MHz will be something usable , we dont know yet.
PaulJ wrote: Sun Dec 15, 2019 2:41 pm (assumption). If this is true could we not add a address to the simm to refresh the next 4 meg on every other refresh occurance. If my assumptions are correct could we get some extended memory easily?
Speed of the system doesn't have anything to do with RAM. The MMU controls RAM, and it can't do over 4MB ST-RAM. We need a new MMU for that.. and as to if TOS will even see the extended ST-RAM is another matter as well. The only current solution is as always, alt-ram which bolts onto the CPU bus, not MMU.. and this is what we are basically doing with the alt-ram boards at the moment.

PaulJ wrote: Sun Dec 15, 2019 2:41 pm I believe I would vote agains the SMT glue and emu. For trouble shooting it can suck to have those devices soldered on. I am building the second H4 with the SMT devices so I could have a change of heart but I doubt it.
Theres no harm in leaving them there along side of the PLCC's until there is something better to replace them with, better to have the choice currently.

PaulJ wrote: Sun Dec 15, 2019 2:41 pm I would be ok with SMT caps. I do have a lot of through hole caps but I would prefer SMT devices, also doesn't SMT free up some board real-estate when routing the board. Bottom line is I can live with either.
It may make routing easier with SMT caps, but its not going to make a huge change. But I think it will be easier to assemble with more SMT stuff long term.
PaulJ wrote: Sun Dec 15, 2019 2:41 pm A connector that would allow a NOVA capable connection to add a ISA video card.
Wouldn't those be to big to fit inside a STFM case anyway ? The connector is pretty big by itself ?
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Re: Potential changes on a future board.

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exxos wrote: Thu Dec 05, 2019 1:24 pm CAPACITORS
I am still in two minds about this..Would we stick to the leaded ones, or go with SMT next time ?
It is actually possible the large 100uF SMT caps may not even be needed.
I quite like the idea of SMT capacitors and resistors. A lot of the resistor banks would be a lot nicer in SMT. i.e. around the ram and floppy areas. For me 0802 it is still feasible to solder in manually.
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Re: Potential changes on a future board.

Post by IngoQ »

Icky wrote: Sun Dec 15, 2019 6:52 pm I quite like the idea of SMT capacitors and resistors. A lot of the resistor banks would be a lot nicer in SMT. i.e. around the ram and floppy areas. For me 0802 it is still feasible to solder in manually.
Second that... Especially upright standing resistors are no fun to solder in my opinion, at least in larger quantities.
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