Amiga 600 schematics nearly put into Kicad

[Mick]

Originally Posted by katarakt

About no version numbers...this is a really bad idea, because there will be some PCBs ordered and nobody knows if it has changes or not. I absolutely recommend using some version info. If there will be changes in the future and the version on github will be replaced you don't see it on the board itself and it will get very confusing

It's too late now. I would like to do a totally unmodified rev 2D but I would need someone to send me 1:1 scans of an empty PCB for measuring. It doesn't matter if there's a bit of damage as long as it's to scale and measurable.

[Mick]

BTW does anyone know how Jens converted Zorro to A1200 connector on the ACA500?

[katarakt]

Originally Posted by Mick

It should all be connected right the only area which may not be great is the video area. I should have just stuck to not modifying anything but the problem of BPF and DL still exists (along with not being able to get one of kipper's keyboards from AOTL within a sensible time frame) which is why I've not really been doing anything more.

I thought S-Video is working?

[Stedy]

Originally Posted by katarakt

I thought S-Video is working?

It is.

It can use the original CXA1145 or the newer CXA2075 encoder which does not need the bandpass filter or delay line.

I am still playing with the bandpass filter/delay line replacement. Tried measuring the original parts, got some odd results (the filter did not work) so will try again at the weekend.

[Mick]

Nah it's designed around CXA2075 although you can probably get away with CXA1145 for just the DB23 output. I'm just not sure if the composite video output with the CXA2075 is as good as it can be. I wish I'd have just done it totally original and left Z221/Z222 to the community. It's too much hassle to build/test another one unless I do a 2D and still have problem of BPF/DL unless someone does one.

[Mick]

If anyone's interested I'm about 150 unrouted on this now (but still unsure about a few things mentioned above).

[katarakt]

Ok thanks Stedy. I have both CXA1145 and CXA2075.

Mick, why do you spent so much time into the A600 with A1200 form factor?? I think there's no need for this, if people want this formfactor they'll go for Chucky's ReAmiga for sure. Better spend more time into the A600 S-Videoboard to get it finishedand add some more things like the bootselector and maybe onboard kickstartswitcher

[Mick]

Like I said, I think it solves all of the A600's flaws and general lack of love/attractiveness. It's called choice if people don't like it don't use it nobody is forcing them.

I've uploaded the KiCad files if you want those things added take a few weeks to learn like I did and add them yourself, I've already done 99.9% of the work for you. Then spend a few hundred quid getting PCB made and building it, then realise you've made a stupid mistake and do it all again in a new revision, it'll be difficult and costly but you'll get what you want in the end and be satisfied. It's not easy but for me it's a labour of love and possibility, instead of waiting for things to come along exactly how I want them I've tried to do what I want myself. A1200 is alright but it's not as compatible unless you like to fiddle with WHDLoad. I never even liked A600 very much it just seemed like a good place to start learning KiCad as everybody else in the community was neglecting it.

[Heywood]

Hey Mick,

Good on you - you did what you wanted, of course people (including myself) cannot
help but offer an opinion on things especially when we arent contributing time/expertise or finance towards an outcome you aren't particularly interested in.

I image you have found it satisfying and frustrating as each minor success and setback has occurred and learnt a lot along the way, thanks for sharing your journey so far.

[eXeler0]

Originally Posted by Stedy

I have a V1 board, it does not boot. I know what is not working but not why?

Mick has a V1.1 board, the one that is on Github and it works.

There is also the Junebug A600 clone, I saw this on Facebook, https://www.facebook.com/groups/2214.../?q=june%20bug
This is a re-creation of the artworks only using Sprint Layout, whereas what we have here are the schematics and PCB recreated. Having the PCB and schematics linked, makes fault finding easier.

I don't use FB, is it this one?
https://www.pcbway.com/project/share...Amiga_600.html

[katarakt]

No, that's Micks and Sedy's one...it seems DJbase put the needeed silkscreen on it but it's wrong, he wrote based on 2D on it but it's 1.1, right?

[Mick]

Originally Posted by eXeler0

I don't use FB, is it this one?
https://www.pcbway.com/project/share...Amiga_600.html

I basically just transplanted footprints over the imported Gerbers for that and then updated it to 2B (with U49 added), I never made the Gerbers for it available I just uploaded the Kicad files to the zone (for educational purposes of course). There's one or two (albeit minor) traces I missed so I never bothered testing it. Not long after that I realised Commodore worked to a 10mil grid and at that point I could measure everything accurately so I re-did it all myself. When I originally started I was measuring everything to the nearest mm so manually routing was a PITA as nothing seemed to line up properly. Damn EU.

Can someone point me to details of the floppy selector mod and I 'll give it a go as I'm even getting Pm's about it now.

I recently came across an old thread of kipper's where he did a component output board for the DB23 utilising Analogue Devices LT6550, I was thinking of stripping out all of the composite rubbish and putting 2 more RCA's where the modulator sits for YCbCr would anyone be able to draw up schematics for it? need to replace the CXA1145 and then have output to the DB23 and LT6550 into Component. Quite a few modern TV's still have component inputs on the back. It's the splitting part I'm struggling with as A600 uses the RGB passthroughs instead.

Page 14 here:
https://www.analog.com/media/en/tech...ts/65501fa.pdf

[SukkoPera]

You can see how the drive switcher is done in my A500 board, it works the same: https://github.com/SukkoPera/Raemixx500

[Stedy]

Hi,

I have a working bandpass filter for the CXA1145 now, just seeing if I can shrink it and make it less complex, to get a smaller solution.
The Delay line will follow shortly. I had to build and test a 20MHz DDS sig gen for the bench tests, which took a bit longer than expected.

Mick, be careful with component video modification. The LT6550 solution does not work with all TVs, it's a Your Mileage May Vary solution. Some TVs will accept component video with a regular bi-level sync (that the Amiga generates) other like my test TV, need a tri-level sync, not generated by the Amiga.

[pandy71]

Originally Posted by Stedy

The Delay line will follow shortly. I had to build and test a 20MHz DDS sig gen for the bench tests, which took a bit longer than expected.

Use Amiga as signal gen - with dedicated pattern (tell me what kind of pattern you need and i can try to create waveform) - it will be faster - alternatively there are some USB to VGA adapters that can be used as arbitrary waveform generators -

https://osmocom.org/projects/osmo-fl2k/wiki
https://sites.google.com/site/oh2ftg/home/osmo-fl2k .

[Rijkyard]

Originally Posted by Mick

[...]
Can someone point me to details of the floppy selector mod and I 'll give it a go as I'm even getting Pm's about it now.[...]

probably you can find information in here too: https://eab.abime.net/showthread.php?t=39776

[squale]

How about modifiying the A1200 motherboard to fit into the A600 case ?

[Stedy]

Originally Posted by squale

How about modifiying the A1200 motherboard to fit into the A600 case ?

Complexity and cost.

Although there appears to be space around the custom chips, it is not available to squish more parts in as that is where the tracks are routed.

To fit more in, you would need more layers. I took the existing A600 design and put it into PCB shopper with the basic size only specified (316x93mm). These were very rough costs per board for 5x:
2 Layer £5
4 layer £11
6 layer £29
8 layer £75

To squeeze an A1200 type design, into smaller area and reduce crosstalk on adjacent on parallel tracks, a 6 layer board with 4 signal and 2 power layers would be the minimum required, the cost is 6x higher. You'd also need your sanity checked!

Changing topic, I have a video bandpass filter working now. I'll try and shrink it down to a small plugin type board. Will play with the delay line if time allows over the next few weekends.

Anyone is free to modify the PCB design, any takers?

[PurpleMelbourne]

Originally Posted by squale

How about modifiying the A1200 motherboard to fit into the A600 case ?

Already on it ;-)

[PurpleMelbourne]

Originally Posted by Stedy

Anyone is free to modify the PCB design, any takers?

I'd sure like a peek!
I loaded Sprint layout to DipTrace and have been linking the schematic to the PCB. Not quite done yet.
For reducing noise, using a sub board for AGA swappable with FPGA makes sense to me.

My secret plan has been to upgrade CPU to 030, Fast RAM and add a DSP56002.