A4000 DIY Motherboard - Page 6

Daedalus · 16 March 2018, 18:03

@elenachen

I've just built this and can confirm that it works perfectly, even with a very noisy/jittery switch. It's a simple enough design, and you could probably use the single-gate version of the Schmitt inverter (74HCT1G14) to save board space if you don't need the other 5 gates in the package. C7 and C8 are just decoupling capacitors for the two logic chips.

MigaTech · 16 March 2018, 18:28

@Daedalus, Nice design really easy to read. Can I just ask about the 40K R5 and the 18K R6, why those values?

Daedalus · 16 March 2018, 18:42

R6 and C6 create an RC circuit that absorbs all the switch jitter. 1uF was picked as a standard value, and the resistor chosen to give a long enough fall time to cover the switch bounce but still give a quick response. The 40K resistor is a pull-up for the circuit, and is part of the RC circuit for when the button is released, giving a slow rise time and also ensuring that the capacitor doesn't charge instantly. The exact values aren't that critical, but the ratios need to be something along those lines to get the input into the Schmitt inverter around the right level. In my prototype I used 18K and 39K resistors as they're more standard values.

MigaTech · 16 March 2018, 18:51

Fascinating stuff!! I could read this sort of reply all day long. You always offer excellent explanations. This helps considering how complicated electronics can get and that we never stop learning! Thanks Daedalus.

Daedalus · 16 March 2018, 19:26

No bother. The specifics of the calculation are written down on a piece of paper lost on my desk somewhere, but I recommend reading up on RC circuits and Schmitt triggers.

elenachen · 16 March 2018, 22:25

Thx for your work, will take this in to the schematic :-)

elenachen · 17 March 2018, 00:47

Well, not as pretty as yours, but it's included now

Daedalus · 18 March 2018, 20:17

Good stuff

Looking busy! Just wanted to check that you're not connecting between R2 and R3 in your diagram?

Chucky · 18 March 2018, 20:18

btw please do the 64MB hack available on the board. (or... the 112 one..

)

grelbfarlk · 18 March 2018, 22:08

Quote:

Originally Posted by Chucky

or... the 112 one..

Does this actually exist?

elenachen · 18 March 2018, 22:32

Whoops, there really is a mistake with R2 and R3. Where can I find that hack? Is there a good source?

grelbfarlk · 18 March 2018, 23:33

Quote:

Originally Posted by elenachen

Whoops, there really is a mistake with R2 and R3. Where can I find that hack? Is there a good source?

I don't think it's a terribly good idea. I would say just add jumpers to make it an option with a socket for the GAL, as it makes SpeedRamsey not work (usually) and is less tolerant of overclocking, in my experience. Also it interferes with old softkicking tools, though there are newer ones now that I think work. Otherwise it works fine.

The original thread is here:
http://www.amibay.com/showthread.php?t=57613

There's also this one buy some guy named John Hertell, can't trust that though seems like it has dark magic swirling around it:

http://wordpress.hertell.nu/?p=303

And.
http://retrocu.blogspot.com/2014/02/...4000-mobo.html

jediknight · 19 March 2018, 03:02

what would be the cost of building one of these love to know?

elenachen · 19 March 2018, 09:49

Sry, I don't know the cost yet, but should be rather expensive, because you probably need to buy the parts in low quantity (Cut Tape) --> high price per piece

I think I leave the Ram Mod out for the first Prototype. I want to have a working one here first and then do mods, if thats ok with you guys. Want to test such things first and implement them then.

But I'll definitely do this, It'll probably be in the released version then anyway. Want to have it working before I release it. Would be a pain for everyone if I release gerber and it wouldn't work. So Keyboard and Mouse hacks have to be enough for now, sry guys.

I can give you all a pre-taste of whats planned in the future after testing then:

64MB Hack
2 Versions of Board --> ATX4000C <--> ATX4000E --- ATX4000C will be classic with zorro and video slots, this is the version as you'll get it first. Later an ATX4000E version will be added.

ATX4000C:
E-ATX formfactor --> Zorro Slots
7 Zorro Slots (if possible)
~4-5 Video Slots --> yes for you toaster freaks :-)
Maybe a version later with Included 68040/68060 onboard.
Replacing GAL's with CPLDs

ATX4000E:
Including 68040/68060 onboard
Replacing GAL's with CPLDs
Scrapping Buster --> Allowing for normal ATX or smaller formfactor
Scrapping onboard RAM except Chipram
Trying to split the bus, to allow native 68060 Bus speed --> 50/66MHz --> the slower half to Chipset --> faster half to a FPGA for PCI/PCIe and to Fast RAM
Adding fast IDE/SATA
Some other onboard stuff, if the PCI/PCIe Bridge works

For now, take this all with a grain of salt. I'm in the process of learning this on the way when I get there. I don't know if I get there and when.

kolla · 19 March 2018, 12:29

Quote:

Originally Posted by grelbfarlk

There's also this one buy some guy named John Hertell, can't trust that though seems like it has dark magic swirling around it

I would not trust anything from that guy, haha

grelbfarlk · 19 March 2018, 12:33

Video Toaster guys don't need 4-5 video slots, just the one for the Toaster, and maybe one for a video slot flicker fixer. Maybe 1 extra for some other oddball video slot device like an Opalvision. What Video Toaster guys need are ISA slots to plug TBCs in, which only draw power. Of course it's not like the old days where you wanted to have a TBC for every input, but at least two of them would be reasonable.

elenachen · 19 March 2018, 13:27

Quote:

Originally Posted by grelbfarlk

Video Toaster guys don't need 4-5 video slots, just the one for the Toaster, and maybe one for a video slot flicker fixer. Maybe 1 extra for some other oddball video slot device like an Opalvision. What Video Toaster guys need are ISA slots to plug TBCs in, which only draw power. Of course it's not like the old days where you wanted to have a TBC for every input, but at least two of them would be reasonable.

ISA Slot for Power is a nice Thing to know. Probably need to do ISA with only Power then. I would leave out Bridgeboard support if possible....

So, 3 Video Slots and 2 ISA?

Or 3 Video Slots and 3 ISA?

Locutus · 19 March 2018, 13:51

Quote:

Originally Posted by grelbfarlk

Video Toaster guys.

...Do those even still exists?

Thats one hell of a niche in a niche in a niche, i cant imagine you could do a viable board run for those amounts of people....

elenachen · 19 March 2018, 13:56

I don't plan to do a viable board run. This is an open source project. You either build yourself one or you don't. If you don't want Video Slots or ISA (Power Slots), just leave them unpopulated. The space on the board is there anyways, because of the huge formfactor requirements of the Zorro.

Locutus · 19 March 2018, 13:59

Quote:

Originally Posted by elenachen

I don't plan to do a viable board run. This is an open source project. You either build yourself one or you don't. If you don't want Video Slots or ISA (Power Slots), just leave them unpopulated. The space on the board is there anyways, because of the huge formfactor requirements of the Zorro.

Oh i do get the idea.

Do keep in mind that all that drilling time for those slots also costs.

16 March 2018, 18:03	#101
Daedalus Registered User Join Date: Jun 2009 Location: Dublin, then Glasgow Posts: 6,334	@elenachen I've just built this and can confirm that it works perfectly, even with a very noisy/jittery switch. It's a simple enough design, and you could probably use the single-gate version of the Schmitt inverter (74HCT1G14) to save board space if you don't need the other 5 gates in the package. C7 and C8 are just decoupling capacitors for the two logic chips. Attached Thumbnails

17 March 2018, 00:47	#107
elenachen Registered User Join Date: Feb 2018 Location: Nürnberg Posts: 97	Well, not as pretty as yours, but it's included now Attached Thumbnails

18 March 2018, 20:18	#109
Chucky Registered User Join Date: Mar 2015 Location: Karlstad / Sweden Age: 52 Posts: 1,210	btw please do the 64MB hack available on the board. (or... the 112 one..)

19 March 2018, 09:49	#114
elenachen Registered User Join Date: Feb 2018 Location: Nürnberg Posts: 97	Sry, I don't know the cost yet, but should be rather expensive, because you probably need to buy the parts in low quantity (Cut Tape) --> high price per piece I think I leave the Ram Mod out for the first Prototype. I want to have a working one here first and then do mods, if thats ok with you guys. Want to test such things first and implement them then. But I'll definitely do this, It'll probably be in the released version then anyway. Want to have it working before I release it. Would be a pain for everyone if I release gerber and it wouldn't work. So Keyboard and Mouse hacks have to be enough for now, sry guys. I can give you all a pre-taste of whats planned in the future after testing then: 64MB Hack 2 Versions of Board --> ATX4000C <--> ATX4000E --- ATX4000C will be classic with zorro and video slots, this is the version as you'll get it first. Later an ATX4000E version will be added. ATX4000C: E-ATX formfactor --> Zorro Slots 7 Zorro Slots (if possible) ~4-5 Video Slots --> yes for you toaster freaks :-) Maybe a version later with Included 68040/68060 onboard. Replacing GAL's with CPLDs ATX4000E: Including 68040/68060 onboard Replacing GAL's with CPLDs Scrapping Buster --> Allowing for normal ATX or smaller formfactor Scrapping onboard RAM except Chipram Trying to split the bus, to allow native 68060 Bus speed --> 50/66MHz --> the slower half to Chipset --> faster half to a FPGA for PCI/PCIe and to Fast RAM Adding fast IDE/SATA Some other onboard stuff, if the PCI/PCIe Bridge works For now, take this all with a grain of salt. I'm in the process of learning this on the way when I get there. I don't know if I get there and when. Last edited by elenachen; 19 March 2018 at 10:09.

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16 March 2018, 18:28	#102
MigaTech Only Amiga !! Join Date: Apr 2017 Location: United Kingdom Posts: 588	*@Daedalus,* Nice design really easy to read. Can I just ask about the 40K R5 and the 18K R6, why those values?

16 March 2018, 18:42	#103
Daedalus Registered User Join Date: Jun 2009 Location: Dublin, then Glasgow Posts: 6,334	R6 and C6 create an RC circuit that absorbs all the switch jitter. 1uF was picked as a standard value, and the resistor chosen to give a long enough fall time to cover the switch bounce but still give a quick response. The 40K resistor is a pull-up for the circuit, and is part of the RC circuit for when the button is released, giving a slow rise time and also ensuring that the capacitor doesn't charge instantly. The exact values aren't that critical, but the ratios need to be something along those lines to get the input into the Schmitt inverter around the right level. In my prototype I used 18K and 39K resistors as they're more standard values.

16 March 2018, 18:51	#104
MigaTech Only Amiga !! Join Date: Apr 2017 Location: United Kingdom Posts: 588	Fascinating stuff!! I could read this sort of reply all day long. You always offer excellent explanations. This helps considering how complicated electronics can get and that we never stop learning! Thanks Daedalus.

16 March 2018, 19:26	#105
Daedalus Registered User Join Date: Jun 2009 Location: Dublin, then Glasgow Posts: 6,334	No bother. The specifics of the calculation are written down on a piece of paper lost on my desk somewhere, but I recommend reading up on RC circuits and Schmitt triggers.

16 March 2018, 22:25	#106
elenachen Registered User Join Date: Feb 2018 Location: Nürnberg Posts: 97	Thx for your work, will take this in to the schematic :-)

18 March 2018, 20:17	#108
Daedalus Registered User Join Date: Jun 2009 Location: Dublin, then Glasgow Posts: 6,334	Good stuff Looking busy! Just wanted to check that you're not connecting between R2 and R3 in your diagram?

18 March 2018, 22:32	#111
elenachen Registered User Join Date: Feb 2018 Location: Nürnberg Posts: 97	Whoops, there really is a mistake with R2 and R3. Where can I find that hack? Is there a good source?

19 March 2018, 03:02	#113
jediknight Registered User Join Date: Feb 2016 Location: bolton Posts: 145	what would be the cost of building one of these love to know?

19 March 2018, 12:33	#116
grelbfarlk Registered User Join Date: Dec 2015 Location: USA Posts: 2,902	Video Toaster guys don't need 4-5 video slots, just the one for the Toaster, and maybe one for a video slot flicker fixer. Maybe 1 extra for some other oddball video slot device like an Opalvision. What Video Toaster guys need are ISA slots to plug TBCs in, which only draw power. Of course it's not like the old days where you wanted to have a TBC for every input, but at least two of them would be reasonable.

19 March 2018, 13:56	#119
elenachen Registered User Join Date: Feb 2018 Location: Nürnberg Posts: 97	I don't plan to do a viable board run. This is an open source project. You either build yourself one or you don't. If you don't want Video Slots or ISA (Power Slots), just leave them unpopulated. The space on the board is there anyways, because of the huge formfactor requirements of the Zorro.

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