M72 Reproduction Rom Board w/ Integrated Multi
I have recreated the M72 ROM board, using SMT components and integrated the Multi that Apocalypse created. This new ROM board is compatible with ALL M72 platforms, meaning that R-type can now be used as a donor for this new ROM board/Multi. I have reached out to @Mitsurugi-w @Apocalypse and have approval and licensing for the use of the Multi on this ROM board.
Since this ROM board is using all discrete components, I can actually build this during the component shortage.
I want to use this thread to gauge interest in this ROM board and see if there is any demand.
As for cost, right now I am at about $400 for the ROM board w/low-profile lower boards. I know, I know - its steep.
The component cost on this one is a bit high with the MB8431, MB8421 and the really nice IC sockets driving the cost up. Also, there is the licensing cost for using the Multi - I have worked out an initial licensing strategy where Apocalypse gets a portion of the profits from each Multi sold.
Interested in First Batch of ROM boards:
1. @jassin000
2. @wolfsoft
3. @2huwman
I have recreated the M72 ROM board, using SMT components and integrated the Multi that Apocalypse created. This new ROM board is compatible with ALL M72 platforms, meaning that R-type can now be used as a donor for this new ROM board/Multi. I have reached out to @Mitsurugi-w @Apocalypse and have approval and licensing for the use of the Multi on this ROM board.
- An original M72 ROM board was captured in KiCad, preserving all the original reference designators and ICs. Net names / pin names were made as consistent as possible with the R-type schematic available. This reproduction ROM board is 95% match with pin numbers and ref designators for the original M72. Pin numbers on the dual-port ram / SRAM were the only changes with the move to SMT.
- IC packages were changed to SMT, keeping as close to the original as possible. The Dual-Port RAM (MB8421, 8431) is the same as the original M72, just in the SMT package.
- Apocalypse Muti was integrated into the ROM board, preserving the reference designators as well
- IC sockets with high temp and high glass content were chosen - this allows the IC sockets to be reflow compatible and allow assembly of the entire board in a reflow oven. (Minus the 2 connectors that interface the ROM board to the M72 stack)
- A new low-profile lower ROM board was also designed. This should allow for the lower ROM board to be installed without needed the additional spacers. The lower ROM board was split into 2 identical smaller boards, that are now linked with a cable. [My LOHT has much shorter stand-offs between the middle and lower board, so this low-profile board still did not fit without longer standoffs - YMMV]
- Don't judge the dupont cable, I only have one of those nice little cables from @Mitsurugi-w
Since this ROM board is using all discrete components, I can actually build this during the component shortage.
I want to use this thread to gauge interest in this ROM board and see if there is any demand.
As for cost, right now I am at about $400 for the ROM board w/low-profile lower boards. I know, I know - its steep.
The component cost on this one is a bit high with the MB8431, MB8421 and the really nice IC sockets driving the cost up. Also, there is the licensing cost for using the Multi - I have worked out an initial licensing strategy where Apocalypse gets a portion of the profits from each Multi sold.
Interested in First Batch of ROM boards:
1. @jassin000
2. @wolfsoft
3. @2huwman
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