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Post by exxos » Tue Aug 22, 2017 10:28 pm

v22.jpg (103.45 KiB) Viewed 47 times
The final V2 booster design as listed above had a great many prototypes before it reached a working versions which I was happy with (as shown above). I thought I would just post 2 of the early prototypes as I found them in my drawer, while looking for something else.

boost1.jpg (142.89 KiB) Viewed 47 times
PCB designed by Rodolphe. It's not very hard to see whats going on above. Classic 68000 CPU there. Plus 2 1MB ROM's. This board suffered badly from various faults and grounding issues and moved to a new design later.

boost2.jpg (162.65 KiB) Viewed 47 times
The next version moved to a PLCC ROM and PLCC 68000 CPU. Though sadly this board ended up being produced twice due to a broken 0v polygon :(

In fact while the bottom of the CPU was actually connected to 0v, the broken polygon caused a bad 0v path and caused a spike between 0v pins on the CPU.. (This actually is one problem with DMA issues on the STE with the CPU)

n1.png (2.02 KiB) Viewed 47 times
This was causing signals on the GAL to reach 7volts! Things went horribly wrong with that layout :( So another batch of PCBs was junked.

It was at that point I decided to move to 4 layer boards. mostly 2 layers for signals, and a dedicated layer for 5V and 0V. Going by each PCB designed had some issue relaying to spikes in 0V paths etc I think it was time to forget 2 layer boards and just move onto something rock solid.

In the end the V2 booster ended up on a 6 layer board, and the development costs, and indeed production costs went though the roof on the V2 booster :(

At the time of typing there is only a couple V2 booster left and it is unlikely there will be produced again. There never seems to be a high demand for boosters, and I can't do them any cheaper without doing larger batches, which I doubt would sell.

While this booster has TOS104 and TOS206 onboard, it also has a 16MHz boost with 16MHz access to ROM. This gave the booster a good kick in speed in desktop apps which used TOS a lot.

Its very similar to the V1.5 booster for the STFM. Similar idea, just without TOS206 built on. I did think as the V2 was large, it only fitted one style of motherboard. Aside from the MEGA ST. It was one reason I produced the V1.5 booster. Though sadly, that seemed less popular than the V2 :( The V1.5 booster could be fitted to probably any machine as well.

I have been working on 32MHz boosters for the STFM. Though I think that work will be suspended, maybe indefinitely as most people seem to want boosters for the STE lately.

If there is interest, I may sell a couple of motherboards fitted out with the V1.5 booster. I know there need a lot of soldering, so possible that is the main reason people are put off buying such things as they do need a lot of soldering. Though it is unavoidable unfortunately.

My past booster work can be found here.

V2 booster webpage ... /index.htm

V1.5 booster webpage ... /index.htm

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