FPGA based A500 accelerator

[thgill]

Would love to see a A600 version.

[kipper2k]

Originally Posted by thgill

Would love to see a A600 version.

I have a lot of conflicting thoughts on how to achieve this, none of them are too pretty. here are my thoughts...

- remove the PLCC CPU on existing A600, making a 64 pin template that lays on the motherboard that routes all the pins to either 2 x 32 pin FFC cable header or other 64 pin header means that will connect to the accelerator.

- for the new a600 motherboard that Mick is designing i could rework it, remove the ROM socket, Remove the PLCC socket and then replace with a 64 pin DIP. (it will fit, i tested it). This would mean that the accel needs some form of ROM simulation.

- on Micks new design, add via holes/pin headers to the PLCC pads and reroute traces out of the way. can then create an adapter for an accel and the ROM remains intact

- create an accel with the PLCC socket that slots over the CPU (YUK, i dont ever want to do this again.

- Create a new edge header on Micks board in the A600 expansion slot that contains all signals needed and uses a common connector. (I like this idea!).

Ultimately i think the A600 (and a few others) are left out of the accelerator market and i am very interested in fixing this issue

Thoughts, Suggestions?

[mkstr]

Originally Posted by kipper2k

Ultimately i think the A600 (and a few others) are left out of the accelerator market and i am very interested in fixing this issue

Thoughts, Suggestions?

I don't see an easy solution for the stock motherboard that doesn't involve a PLCC clip or major mods. The data bus and most of the address bus is on the ROM socket but some of the address bits, the clock and all of the control strobes would still need to come from somewhere else.

Plugging into the ROM socket purely as a mechanical anchor to help stop a PLCC clip from popping off might work, either with the ROM on top or mapped by the accel. I think it would be a completely different board layout rather than an adapter for the DIL version (to keep height down), but if there is enough interest I see no reason not to do it at the same time as the logic will be the same.

Mike

[Lemaru]

Originally Posted by mkstr

I don't see an easy solution for the stock motherboard that doesn't involve a PLCC clip or major mods. The data bus and most of the address bus is on the ROM socket but some of the address bits, the clock and all of the control strobes would still need to come from somewhere else.

Plugging into the ROM socket purely as a mechanical anchor to help stop a PLCC clip from popping off might work, either with the ROM on top or mapped by the accel. I think it would be a completely different board layout rather than an adapter for the DIL version (to keep height down), but if there is enough interest I see no reason not to do it at the same time as the logic will be the same.

Mike

If you use a decent PLCC socket then you can get a pretty good fit. I have one of Kipper2ks vampire V2 cards which was driving me mad with stability issues. Replaced the socket with an Augat one after having the same socket on a Furia with no issues. I can now lift the whole Amiga by the vampire alone without the need for any additional screw and it's perfectly stable.

When I get a moment I am going to design an adaptor similar to Kludge's ice scraper plcc to dip adaptor which works with other A500 cards. Have some ideas for a better layout, and a 3d printable mount to support the card.

Also having such an adaptor would mean I could one card for use in both an a500 and a600.

Once Mike's A600 board is working, I think they way to go with that would be to swap the 68k for a dip version so that there is potential to use any dip mounting card, rather than use a new style design like edge connector or anything non standard.

[kipper2k]

Do you have a part # for the new plcc socket you re using ? and does the inside need scraping etc ?

Originally Posted by Lemaru

If you use a decent PLCC socket then you can get a pretty good fit. I have one of Kipper2ks vampire V2 cards which was driving me mad with stability issues. Replaced the socket with an Augat one after having the same socket on a Furia with no issues. I can now lift the whole Amiga by the vampire alone without the need for any additional screw and it's perfectly stable.

When I get a moment I am going to design an adaptor similar to Kludge's ice scraper plcc to dip adaptor which works with other A500 cards. Have some ideas for a better layout, and a 3d printable mount to support the card.

Also having such an adaptor would mean I could one card for use in both an a500 and a600.

Once Mike's A600 board is working, I think they way to go with that would be to swap the 68k for a dip version so that there is potential to use any dip mounting card, rather than use a new style design like edge connector or anything non standard.

[Lemaru]

Originally Posted by kipper2k

Do you have a part # for the new plcc socket you re using ? and does the inside need scraping etc ?

The socket I use is an Augat pcs-068a

I think they may have been discontinued however although others I have recommended then too have found them ok. Unfortunately there is 4 little nubs that need taking out and it still needs to be sanded down until the edge of the socket is level with the pins. I use a little sanding wheel to do this to save time. Over in the a1k forums they also recommend a Fischer socket as being a great fit.

I guess as it's using a PLCC socket in a way that it's not designed for there is always going to have to be some modification to.the socket required. Aranet recommends SMT sockets instead of THT as they sit lower on the IC so probably requires less work

[thgill]

The socket that the Furia uses is extremely strong.

You can pick the A600 up by lifting the Furia without them separating.

And not just the motherboard. Motherboard, bottom case and even floppy drive still attached!

[Lemaru]

This is the Fischer one that was recommended on A1k.org but I can't vouch for it personally as I stocked up on Augat ones

https://www.buerklin.com/de/Produkte...A0mm/p/15B5274

[kipper2k]

initial design...



will prob need tweaking a bit but this is the general idea
so there wont be any soldering. Height clearances should be good

[Lemaru]

I didn't think of using the ROM socket as additional support. Did consider using the IDE header and just relocating that on the adaptor too. But some of the a500 cards have their own IDE that's faster then the A600s anyway.

I did also thing of rotating the dip 90 degrees so the adaptor is more of an L shape. (The dip would be in similar orientation as to in the A500 then too, and can use the upper HDD screw hole too)

[kipper2k]

Originally Posted by Lemaru

I didn't think of using the ROM socket as additional support. Did consider using the IDE header and just relocating that on the adaptor too. But some of the a500 cards have their own IDE that's faster then the A600s anyway.

I did also thing of rotating the dip 90 degrees so the adaptor is more of an L shape. (The dip would be in similar orientation as to in the A500 then too, and can use the upper HDD screw hole too)

I stayed clear of the IDE in case people need it, we wont need it and the clearance will be good for what we want. We also wont need the rom but the rom socket can be included on this design by offsetting it a little to the right and upwards

with the rom, plcc and a 1.6mm screw this board wont move

[thgill]

Will there be a fast IDE/bootable storage option on the accelerator? I would love something faster than the built in IDE on the 600. SD card on it would be perfect.

[mkstr]

Originally Posted by thgill

Will there be a fast IDE/bootable storage option on the accelerator? I would love something faster than the built in IDE on the 600. SD card on it would be perfect.

Looking at options for that. Gayle IDE is slow (PIO mode only). There will definitely be something.

[thgill]

That’s great news!

[kipper2k]

k, the A600 PLCC CPU Converter PCB is done, no pictures till it gets proven to be good . ( I don't want people blaming me for wasting their money

[Lemaru]

Originally Posted by kipper2k

k, the A600 PLCC CPU Converter PCB is done, no pictures till it gets proven to be good . ( I don't want people blaming me for wasting their money

Out of interest, what method have you used to disable the onboard CPU? Just connecting BR and VPA to ground on the PLCC side and to 5v on the DIP side?

[Lemaru]

Another nice feature of the PLCC - DIP adaptor I was thinking of for mine would be the ability to switch between passthrough mode, or disabled CPU mode. That would allow people to use memory expansions and such where the CPU does not need to be disabled.

I guess it depends if you are just aiming to support this accelerator, all accelerators (well the ones that will work), or all A500 dip mounting add-ons.

[kipper2k]

We are looking at a similar method as you described to prevent bus contention and also have the option to re-enable the onboard CPU so you can leave the adapter on even when there is no Accelerator connected.

The A600 does not have a lot of room, i am looking at the dimensions and the physical height of some of these boards and it does not look good for some of them, they will need a rework. it is possible to reroute the adapter, i have tried to make it as compact as possible, and i have also made it so that a rom can be placed on the adapter for those accelerators that need it

[mkstr]

Originally Posted by kipper2k

We are looking at a similar method as you described to prevent bus contention and also have the option to re-enable the onboard CPU so you can leave the adapter on even when there is no Accelerator connected.

The A600 does not have a lot of room, i am looking at the dimensions and the physical height of some of these boards and it does not look good for some of them, they will need a rework. it is possible to reroute the adapter, i have tried to make it as compact as possible, and i have also made it so that a rom can be placed on the adapter for those accelerators that need it

With size constraints in mind I will consider doing an A600 specific version of the accel if there is enough interest, but this adapter will work for dev and anyone that can't wait!

[Lemaru]

Originally Posted by kipper2k

We are looking at a similar method as you described to prevent bus contention and also have the option to re-enable the onboard CPU so you can leave the adapter on even when there is no Accelerator connected.

The A600 does not have a lot of room, i am looking at the dimensions and the physical height of some of these boards and it does not look good for some of them, they will need a rework. it is possible to reroute the adapter, i have tried to make it as compact as possible, and i have also made it so that a rom can be placed on the adapter for those accelerators that need it

Yeah room will also be an issue, but mine will eventually go in my Checkmate case thats been sat in its box for 6 months or so waiting for me to decide what to put in it.

This is why I was looking to have the DIP mounted vertically, rather than horizontally. So basically above the PCMCIA, as then the length of cards won't be such an issue. I guess some will still be an issue in the original case, but it will mean that the dimensions of whatever card is used won't be an issue in the Checkmate case (as it won't then hit the rear).

I guess there can always be a workaround of making a "shim" to lift the top of the original case up a bit if needbe for those that don't fit at all