Amiga hardware info, help and support with a focus (but not limited to) North American NTSC experiences. Open to all.
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intric8
Seattle, WA, USA

by intric8 posted Fri Jul 19, 2019 9:39 am

You guys have got to take a look at this fascinating project. It is a reimplementation of the Amiga 1200 motherboard as derived from the original schematics. But the creator, Jeroen Vandezande of the Belgian Amiga Club, has gone a step further and modified his new 1200 motherboard (hence the 'plus') in several key way.

Vandezande lists the new features as such:
  • All Original AA chips are needed and can be put into the sockets. These include Lisa, Paula, Alice, The two CIA chips and the Keyboard controller.
  • Gayle, Budgie and the DRAM have been removed and the functionality has been moved to a daughterboard. This board can also contain a CPU.
  • Video output has been moved to a seperate output board. This board get all Lisa output signals and also all the typical Zorro signals. This means that an RTG card can be developed.
  • The PCMCIA slot has been removed and in the free space a power switch, boot selector switch (DF0:/DF1:) and a uSD card slot have been added.
  • A single modern universal power input that accepts multiple voltages

And more. Definitely check it out.

Also, it's 100% open source! Incredible. (And he's gotten it to boot!) <3
Attachments
render.jpg
Image by Jeroen Vandezande
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obitus1990
New Orleans, LA, USA

by obitus1990 posted Fri Jul 19, 2019 7:43 pm

It is very promising, but, I don't think it's 100% functional yet, based on questions he asks in the Amiga facebook group.
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Bulletdust

by Bulletdust posted Sat Jul 20, 2019 12:37 am

I really like the idea of a separate graphics board with the possibility of future RTG graphics solutions, this is pretty cool.

The problem is getting hold of the custom chipset to fit to the board, there's no way I'd butcher my A1200 for a third party PCB and the custom chips are fairly pricey if you can find them.
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CD32Freak

by CD32Freak posted Tue Jul 23, 2019 7:38 am

It would be more impressive if he replaced the original chipset with FPGA's and creating an open sourced Clone-A :-)
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Zippy Zapp
CA, USA

by Zippy Zapp posted Tue Jul 23, 2019 9:54 am

CD32Freak wrote:It would be more impressive if he replaced the original chipset with FPGA's and creating an open sourced Clone-A :-)

One that can use original floppy drives, and all the usual ports on an Amiga, sort of like the Ultimate 64. I could see that.

I don't mind the FPGA implementations that exist today but everything is emulated to the point where you can't really hook up anything to it besides keyboard, mouse and monitor. I want a replacement that allows complete compatibility with all hardware.
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nonarkitten

by nonarkitten posted Fri Aug 09, 2019 4:14 pm

Zippy Zapp wrote:
CD32Freak wrote:It would be more impressive if he replaced the original chipset with FPGA's and creating an open sourced Clone-A :-)

One that can use original floppy drives, and all the usual ports on an Amiga, sort of like the Ultimate 64. I could see that.

I don't mind the FPGA implementations that exist today but everything is emulated to the point where you can't really hook up anything to it besides keyboard, mouse and monitor. I want a replacement that allows complete compatibility with all hardware.


I agree, and this is how I'd do it.

Make three PCB's. One mainboard, two different IO boards and three different joystick boards. These would use right-angle headers like the Amiga 500 trapdoor expansion to connect with each other. The two IO boards are for the different layout between the 500 and 600/1200 and ordered separately. The IO and mainboard are the same "width" across the back.

The joystick PCBs can be mounted in either the A500/A1200 position (looking very long like the Ultimate 64) or sideways as in the A600 (making an "L" of the three boards). They come in three configurations: dual DB9, dual USB or single DB9+USB.

For the CPU, I'd use a simple DIP socket for a conventional 68000 processor allowing you to install a stock MC68000 or any of the many accelerator options available, up-to and including the Vampire V500. Since there's nothing about the Amiga chip set that leverages 32-bit addressing, the older 23-bit addressing and 16-bit data bus is fine -- even for most things AGA.

Finish off with a modest (12~24K Lattice EP5C?) FPGA for the chipset and 16Mb Pseudo-SRAM (and obligatory passive and level shifting). Should make for a fairly inexpensive setup.

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