Proposed next H4 board.

Post by **exxos** » 13 May 2020 16:34

What I would start a new thread on all this...

The current board is a H4 rev G... where @Icky Changed a lot of the resistors and capacitors for SMT ones.. for example...

Capture.JPG

I already did the fixes for the DAC, DMA etc (but I need to double check on all that some other time)

I am considering adding a 3.3V bus where the flashy clock socket is and adding a additional one to the left of it... Basically this would have the level translators on the motherboard instead of the flashy clock PCB.. I have plans for a different version of flashy for the H4.. And I may even do away with the 68K sockets and you something a little wider to make things easier to route on the add-on boards.

Other considerations as I may put jumpers on the upper MAD lines on the RAM, basically to do a hardware switch between 512K,1MB,4MB.

As this board is more SMT based, with the PLCC MFP chips being cheap, I may just rip out the DIP MFP and just stick with the PLCC MFP soldered directly to the motherboard.

I may also remove the row of jumpers next to the ROM & GLUE is really they were for experimenting with the 16MHz bus stuff.. Long story short, I just don't have the time to start that project again, and it is basically a dead-end road as we need to move over to a FPGA based MMU to get up to 32MHz.

So there will not be any huge changes as such on the next board, but I think that will basically be the final board which will be produced of that series.

troed · Post by **troed** » 13 May 2020 16:52

Not sure what you mean with 16MHz bus, but my intention for my H4 build is to build it into a doubleST, same as I did with an original STF. I'm hoping this can then be a fully supported mode of the STF remake.

/Troed

Post by **terriblefire** » 13 May 2020 16:54

Suggestion from me is to get all the passives and other smt components onto one side of the board so that you can get assembly done as part of the PCB order. That will take a lot of the pain out of the build for people.

Post by **exxos** » 13 May 2020 16:59

troed wrote: 13 May 2020 16:52 Not sure what you mean with 16MHz bus, but my intention for my H4 build is to build it into a doubleST, same as I did with an original STF. I'm hoping this can then be a fully supported mode of the STF remake.

The jumpers were there for the "doubleST"... But the original pcb I did for the alpha was a nightmare to get working... @kodak80 Started a thread on this a few weeks about it I think, but I just don't have time to get involved with that again at the moment... Even so I designed a new board which should help solve the wake up state issues... But again is another project I would have to spend a lot of time on it which may not ultimately work anyway.. So I basically just abandoned the idea in favour of just working on the FPGA stuff instead. Once we have a proper FPGA MMU & GLUE those wake-up issues will no longer be a problem and we can have a 32MHz bus etc.

troed · Post by **troed** » 13 May 2020 18:19

exxos wrote: 13 May 2020 16:59 The jumpers were there for the "doubleST"... But the original pcb I did for the alpha was a nightmare to get working... @kodak80 Started a thread on this a few weeks about it I think, but I just don't have time to get involved with that again at the moment... Even so I designed a new board which should help solve the wake up state issues... But again is another project I would have to spend a lot of time on it which may not ultimately work anyway.. So I basically just abandoned the idea in favour of just working on the FPGA stuff instead. Once we have a proper FPGA MMU & GLUE those wake-up issues will no longer be a problem and we can have a 32MHz bus etc.

Right, I'll try to move quickly with my H4 build and see what I can get running. I would assume if I just connected up the GAL I already have working I should get quite far right away.

/Troed

Post by **exxos** » 13 May 2020 18:41

troed wrote: 13 May 2020 18:19 Right, I'll try to move quickly with my H4 build and see what I can get running. I would assume if I just connected up the GAL I already have working I should get quite far right away.

All the lines you need are jumper linked on the H4... So wiring it up should be relatively easy, getting it to actually work is another matter...

officer960 · Post by **officer960** » 19 May 2020 20:56

terriblefire wrote: 13 May 2020 16:54 Suggestion from me is to get all the passives and other smt components onto one side of the board so that you can get assembly done as part of the PCB order. That will take a lot of the pain out of the build for people.

@exxos is this a possibility; or put another way, should I wait? IIRC in some other thread you were kicking around the idea of having a version that was partially or fully assembled - one that mediocre solderers such as myself could populate with our ST's custom chips. I really want one of these BAD but frankly I waffled and missed out on the last run because I don't trust my skills enough to take on the full build. :(

Also, thank you (and the rest involved) for taking this on. Its about time the ST gets some updated motherboards/plug-n-play upgrades Amiga users have had for quite a while.

Post by **exxos** » 19 May 2020 21:27

officer960 wrote: 19 May 2020 20:56 @exxos is this a possibility; or put another way, should I wait? IIRC in some other thread you were kicking around the idea of having a version that was partially or fully assembled - one that mediocre solderers such as myself could populate with our ST's custom chips. I really want one of these BAD but frankly I waffled and missed out on the last run because I don't trust my skills enough to take on the full build. :(

There is nothing on the bottom of the board anyway.. I did consider putting the SMT caps on the bottom, decided it will be better to have everything on one side anyway.

I have waffled on about load of things relating to this in my blog over the past couple of days as well.

officer960 · Post by **officer960** » 19 May 2020 21:35

Thanks for the reply, was mostly wondering if there will be a future (I know a lot of this is undecided, etc) version where the PCB house installs the caps and the SM components? I'd gladly pay the extra for one that was pre-built or mostly built.

Post by **exxos** » 19 May 2020 21:37

officer960 wrote: 19 May 2020 21:35 Thanks for the reply, was mostly wondering if there will be a future (I know a lot of this is undecided, etc) version where the PCB house installs the caps and the SM components? I'd gladly pay the extra for one that was pre-built or mostly built.

I would get the fab house to fit as many SMT parts as possible.. but they can only do generic parts... But at least it will be a fair chunk of the board already assembled. As I said in my blog, I was considering getting a soldering machine to do the through-hole parts like the sockets, but I don't think it will happen. So likely people would have to solder them themselves, or they go off to the assembly company to be fitted like last time. But I am really trying to avoid keep packing and shipping stuff backwards and forwards as it just takes months to get stuff back :(

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