Another new A500+ motherboard
 

Hi All,

I haven't been online a lot lately, lot of things going on, however...

Here is my latest creation based on Sukkoperas A500 remake. I have made a lot of changes. I have been using Eagle for the last 10 years and i decided to start using Kicad... *beginning of May this year, then i find out Eagle Cad is being cancelled so it was a case of necessity to learn Kicad, and as luck would have it i found it extremely easy to use. It has only taken a few weeks to get to this point...

I am not sure if i will make more substantial changes/additions. 8MB fastmem and IDE are a good possibility.

I will show the pictures first...

https://cdn.discordapp.com/attachmen...bie002_800.jpg

There is the board, it has a few additions to it and you can notice for the most part it is mostly SMD....

(Marios, thanks for your help. i got busy and sidetracked, sorry :)


here is next picture...

https://cdn.discordapp.com/attachmen...bie001_800.jpg

Talking about the features, ...

2MB Chipmem (Thanks Liv2)
on board Gotek
USB Smally Mouse (Thanks to Simon Inns)
Allows 27cxxx eproms up to 4 ROM images, auto switch (Thanks to Mike Stirling)


I am working on some others. The board is still 2 layer. I can now remove the old RAM footprints and probably add 8MB fastmem and IDE, we'll see


I would like to put on Action Replay 3 but i dont have code/schematics, if someone willing to allow me to add it let me know

This is awesome, I love how more than 30 years after they stopped making them! I think the only other upgrades I can think of that might commonly be used is:
usb keyboard, I have an adapter thing I bought off ebay, I towerised my a500 so it makes it easier for plugging in external keyboards as my original failed.

Maybe is it possible to have a native plug in port for rgb2hdmi? I'm think it would essentially be adding in that video stuff and just providing a 40pin header for for the raspberry pi. I wonder on that note of the video section of the board could be modulised so you could take out standard video and drop in an rgb2hdmi module so the slot in the back of the case could have hdmi so no cutting :)

Is there any advantage to go down the route of smd?

Sent from my SM-G991B using Tapatalk

The nice thing about SMD is the fact that ...

- board houses can assemble most of the board saving the end user a lot of tedious soldering and improving success probability rate

- SMD parts are more available now and cheaper..

- There are less holes in the board and wires poking through which always seem to get your fingers.

- the board wont get as dirty now when building as a lot of the work is done

- SMD components are a lot smaller than the old through hole allowing more upgrade options.

- i could continue and replace all logic chips with SMD type, not sure whether to do that as a repair/debugging would become harder.

- not too sure on heat/power consumption, i think overall there would be a power usage reduction.

This project started because i wanted to add a soft reset button to the board and then i got a little carried away lol (there is a reset button on it too, hidden in the picture behind the keyboard cable)

Man I love these kinds of threads :)
Great work!

Well done with this, Kipper! I'm happy someone finally gets the point of Open Source Hardware.

Now just be careful to respect the licensing terms. We can talk about this, if you want.

Thanks for all your hard work. Looks amazing. I will be watching closely to see where this goes.

Out of curiosity what is happening with the Agnus Replacement project? I see a commit from nonakitten in April.

Getting a 2MB Agnus is getting to be practically and economically impossible due the the amount of A3000++ and other Amiga remake boards out there which use 8375 2MB agnii

So dumpin old RAM and RAM support it appears i have lots of room for stuff...

https://cdn.discordapp.com/attachmen...0883/noram.jpg

(I'll have to verify)

great project and great to see you back with new cool Amiga stuff:spin

i was looking at the "A314" and it would probably fit, it could be modified as the board already has a RTC and 2MB RAM, and not too sure of the full functions but it could be used as an IDE Device ?

Not sure if i am allowed to implement it onto the motherboard though ? (it should fit with a rework)


p.s. just looked for Max10 availability and seems no one has stock no more

Some ideas:

- SPI interface (could replace IDE) + ethernet?
- support for 1.5MB ranger RAM out of the box?

Once you have SPI, you have Ethernet as well. And to do Ethernet right it has to be included on the motherboard.
I have been struggling with random errors in my "simple SPI" project and found that it is an EMC problem. These long ethernet cables pick up a lot of (common-mode) stuff that needs to be properly diverted to chassis ground. An Aliexpress ENC28J60 module dangling on a few jumper wires doesn't cut it.
But, once you are re-doing the motherboard, you can do things right EMC (and signal integrity) wise.

Going to a four layer PCB would be great if EMC/EMI is a concern...
https://www.youtube.com/watch?v=crs_QLuUTyQ
but downside is of course a higher PCB cost.

For this particular problem a 4 layer PCB is not needed at all. It has more to do with properly grounding and edge control of the SPI clock signals.

If you take a peek at the board picture you can see that i havent added any electrolytics yet and it appears stable, i am trying when i build to use as little components as i can in order to see if it boots instead of wasting components. I added the 8MB fastmem to the board, still have room left. For IDE i do have a working 8MB/IDE fastmem board i can port over. I need to stay clear of anything that is considered a WIP as the cost of the boards are a killer for me hence the reason to try to stick with 2 layer, it may not be possible sooner or later with all the addons and it will be a while to free up some cash for the next Rev.

Understandably to stay with proven tech! Indeed these big boards are costly.
Maybe it is possible to add some extra expansion headers? A bit like the infamous clock port header? And then preferably with some extra ground pins with big fat traces to the chassis (= shield pins on the SUB-D connectors)

yup, sounds good, i would like to get a 40 pin Pi header too. Add a CPLD RGB > HDMI circuit to the board for more video options, i may have to put the CPLD on the underside due to physical space limitations. Hopefully there is room

Oooh nice. I like the idea of an integrated Gotek

I assume the KiCad files will be shared once it's complete?

Holy cow, this looks awesome, and SukoPerras hard works and Open source comes to good use. This is the sort of stuff we hoped would happen. Hats off for Suko and Kipper2k ?[emoji2532]

@Kipper2k, any chance you could design an A500/020 and possibly an A500/030 ? To have these CPUs on-board would be awesome, specially with built in Fast RAM.

These versions would offer a non clumsy A500. It would be all on-board, making it superior to any other design.

Could it be possible to tap into the 68K lines and by pass the 68000 and DIL altogether? Technically, replacing the 68000 for the SMT 020 and 030.

This looks great! Thank you for sharing, for the many hours spent, and all of the new ideas!

With all the options for drop in accelerators now i dont think modifying the a500 would be a good idea as it would lose all of the capabilities of these accelerators being added. I want to try to leave it as stock with just adding the common items that most people have in their A500 already.