The Signetics 2650 found its way into a bunch of arcade games by lieu of British company Century Electronics. I have a conversion kit of theirs installed into a Donkey Kong Jr. board, which outright replaces DK Jr.'s Z80 with a daughterboard containing the CPU. Always wondered why they chose that in particular, it's not a very common chip, and just using the Z80 that was there and replacing the ROMs was the more common option for conversion kits like that.
The 2650 was one of the first microprocessors on the market you could buy, it was shockingly simple to design, and had some dedicated I/O lines. Look up the reference schematic and compare to what a 6502 or Z80 needs. It was used in a lot of early embedded systems. It makes sense in that light
Given the era, I wouldn't be surprised if it came down to "someone on the development team liked that part". (Or "someone in the purchasing department got a bunch of them really cheap".)
Comments
The Signetics 2650 found its way into a bunch of arcade games by lieu of British company Century Electronics. I have a conversion kit of theirs installed into a Donkey Kong Jr. board, which outright replaces DK Jr.'s Z80 with a daughterboard containing the CPU. Always wondered why they chose that in particular, it's not a very common chip, and just using the Z80 that was there and replacing the ROMs was the more common option for conversion kits like that.
The 2650 was one of the first microprocessors on the market you could buy, it was shockingly simple to design, and had some dedicated I/O lines. Look up the reference schematic and compare to what a 6502 or Z80 needs. It was used in a lot of early embedded systems. It makes sense in that light
Zaccaria pinballs I think used it pretty heavily as well. Again, no clear explanation there either.
Given the era, I wouldn't be surprised if it came down to "someone on the development team liked that part". (Or "someone in the purchasing department got a bunch of them really cheap".)