H4 16mhz modification

Topic for users to share their building progress.
User avatar
kodak80
Posts: 260
Joined: Sat Oct 21, 2017 1:14 am
Location: Brisbane,QLD Australia
Contact:

H4 16mhz modification

Post by kodak80 » Fri Feb 21, 2020 11:54 pm

Thought I would start a new post for this. Will the PCB work for the H4? Just wondering if I should finish building one to start testing the H4?

Image
Atari Falcon 030 | Atari 1040 STE | Atari 1040 STFM | Atari 1040 STF | Kryoflux & Supercard Pro Flux boards
Creator of the Atari ST Review magazine archive: https://www.chillichai.com/atari-st-review

User avatar
Icky
Moderator
Moderator
Posts: 2493
Joined: Sun Sep 03, 2017 10:57 am
Location: UK
YouTube: https://tinyurl.com/yals4a3k
Contact:

Re: H4 16mhz modification

Post by Icky » Sat Feb 22, 2020 12:06 am

@kodak80 - I had started this mod a while back but have too many projects on the go to debug.

I jumpered R913 so that I could isolate the on-board oscillator and plug the mod board in. It is easier on the H4 to tap into the jumper bank to feed the right chips etc the new clock signals.

Picture of R913 jumpered with resistor on a jumper socket and shrink wrap.

IMG_4731.jpeg
IMG_4731.jpeg (174.39 KiB) Viewed 973 times

User avatar
exxos
Site Admin
Site Admin
Posts: 12239
Joined: Wed Aug 16, 2017 11:19 pm
Location: UK
YouTube: https://www.youtube.com/user/exxosuk
Contact:

Re: H4 16mhz modification

Post by exxos » Sat Feb 22, 2020 12:37 am

I designed a new one ages ago, but no time to test and no H4 to test even.
https://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxoshost.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.

User avatar
kodak80
Posts: 260
Joined: Sat Oct 21, 2017 1:14 am
Location: Brisbane,QLD Australia
Contact:

Re: H4 16mhz modification

Post by kodak80 » Sat Feb 22, 2020 12:39 am

@Icky With R913 as a jumper, we can feed the 32mhz CLK signal into the Mod board rather than have the OSC on the Mod board itself which would mean that for future PCB mods the 16mhz Mod board could be made smaller by removing the on-board OSC.
Atari Falcon 030 | Atari 1040 STE | Atari 1040 STFM | Atari 1040 STF | Kryoflux & Supercard Pro Flux boards
Creator of the Atari ST Review magazine archive: https://www.chillichai.com/atari-st-review

User avatar
kodak80
Posts: 260
Joined: Sat Oct 21, 2017 1:14 am
Location: Brisbane,QLD Australia
Contact:

Re: H4 16mhz modification

Post by kodak80 » Sat Feb 22, 2020 12:41 am

exxos wrote:
Sat Feb 22, 2020 12:37 am
I designed a new one ages ago, but no time to test and no H4 to test even.
If you want the new design PCB testing, I would be happy to get some created and tested but I can probably start with the current one and as suggested, feed 32mhz CLK to it from the H4 OSC.
Atari Falcon 030 | Atari 1040 STE | Atari 1040 STFM | Atari 1040 STF | Kryoflux & Supercard Pro Flux boards
Creator of the Atari ST Review magazine archive: https://www.chillichai.com/atari-st-review

User avatar
exxos
Site Admin
Site Admin
Posts: 12239
Joined: Wed Aug 16, 2017 11:19 pm
Location: UK
YouTube: https://www.youtube.com/user/exxosuk
Contact:

Re: H4 16mhz modification

Post by exxos » Sat Feb 22, 2020 12:47 am

kodak80 wrote:
Sat Feb 22, 2020 12:41 am
If you want the new design PCB testing, I would be happy to get some created and tested but I can probably start with the current one and as suggested, feed 32mhz CLK to it from the H4 OSC.
Its one of those things I need to sort out myself, its totally untested and likely need a lot of tweaking... like the previous mod, takes a lot of trial and error to get the thing even half working.


EDIT:

In theory the old mod should work like on the Alpha, but I suspect it will need a lot of messing about... plus there is the "1 in 4 chance" of it atually booting because of the random clock skew (which I hope might be better on the new board) . So if you want to try and get the current board work, have fun ;)
https://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxoshost.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.

User avatar
kodak80
Posts: 260
Joined: Sat Oct 21, 2017 1:14 am
Location: Brisbane,QLD Australia
Contact:

Re: H4 16mhz modification

Post by kodak80 » Sat Jul 04, 2020 10:05 am

Spent some time today looking at starting this on one of my H4 boards.

I have built one the 16mhz mod boards and tested the clock output on this is as expected with the 32mhz OSC on the mod board.
download/file.php?id=6796

First thing I have found is that the jumper pins on the board do not match the schematic image, in that the pins may be the opposite way round on the board.

Image removed to stop confusion. See image in next post
Atari Falcon 030 | Atari 1040 STE | Atari 1040 STFM | Atari 1040 STF | Kryoflux & Supercard Pro Flux boards
Creator of the Atari ST Review magazine archive: https://www.chillichai.com/atari-st-review

User avatar
Icky
Moderator
Moderator
Posts: 2493
Joined: Sun Sep 03, 2017 10:57 am
Location: UK
YouTube: https://tinyurl.com/yals4a3k
Contact:

Re: H4 16mhz modification

Post by Icky » Sat Jul 04, 2020 10:27 am

Hi @kodak80, yes the pins dont match the schematic as layout usually always different to the schematic.

There are a few pins not quite right in your picture. I am just updating an image with the correct pin layout for you.

User avatar
Icky
Moderator
Moderator
Posts: 2493
Joined: Sun Sep 03, 2017 10:57 am
Location: UK
YouTube: https://tinyurl.com/yals4a3k
Contact:

Re: H4 16mhz modification

Post by Icky » Sat Jul 04, 2020 10:49 am

Lifted directly from the board layout. Slight spelling mistake on DE_MM should be DE_MMU.

Screenshot 2020-07-04 at 10.27.49.png
Screenshot 2020-07-04 at 10.27.49.png (384.89 KiB) Viewed 546 times

User avatar
kodak80
Posts: 260
Joined: Sat Oct 21, 2017 1:14 am
Location: Brisbane,QLD Australia
Contact:

Re: H4 16mhz modification

Post by kodak80 » Sat Jul 04, 2020 10:53 am

Thanks @Icky image is easier to read than mine.

Updates copy here:
H4 JUMPERS-Icky.png
H4 JUMPERS-Icky.png (356.89 KiB) Viewed 538 times
Will look to connect things up tomorrow. :D
Atari Falcon 030 | Atari 1040 STE | Atari 1040 STFM | Atari 1040 STF | Kryoflux & Supercard Pro Flux boards
Creator of the Atari ST Review magazine archive: https://www.chillichai.com/atari-st-review

Post Reply

Return to “MONGREL H4 USER BUILDS”