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Nintendo also had something I think is a great idea when developing the NES: the video hardware had its own bus to the cartridge. This probably saved many cycle

Nintendo also had something I think is a great idea when developing the NES: the video hardware had its own bus to the cartridge. This probably saved many cycles keeping the processor busy with other things instead of transferring content to the video RAM. It also allows better use of the system's very limited RAM and video RAM. I don't know if there was any patent related to this, and I can't understand why SEGA didn't copy it. Maybe it could make the console more expensive since SEGA didn't produce their own chips and maybe they were really expecting to make ports easier. I still think a bus connecting the video hardware to the cartridge could make the Master System way more powerful.

JohnBooty 4y ago
God, yeah. It's very difficult for me to look at retro game hardware design decisions without obsessing over "what if?" scenarios. My favorite (and by that I mean, "most agonizing") what-if's concern the Genesis/Megadrive. I don't have handy links, but: - There was some sort of hardware fail that prevented clear sample playback. The sound chip could play back crystal clear samples but in reality, this was impossible to achieve thanks to some issue (DMA? bus? something?) and in reality, sampled sounds on the Genesis sounded like butt - The Genesis' limited color palette and number of onscreen colors relative to the SNES and even the TG16 was kind of painful. I remember reading that one reason for this limitation was the need to include backwards compatibility with the SMS in the Genesis' video chip -- a feature few if any cared about or used. Arrrrgh. A Genesis with color to rival the SNES/TG16 would have been such a fearsome beast.
deaddodo 4y ago
> Nintendo also had something I think is a great idea when developing the NES: the video hardware had its own bus to the cartridge. This probably saved many cycles keeping the processor busy with other things instead of transferring content to the video RAM. It also allows better use of the system's very limited RAM and video RAM. Nintendo did this because they had to, not because it was an ingenious innovation. Sega didn’t do it in the SMS/GG for the same reason Nintendo didn’t do it in the GB or GBA; because those architectures were much more efficient at ferrying data due to their high cycle counts. The Z80, for the most part, at 4MHz is about equivalent to a 6502 at 1MHz due to architectural differences / differing design decisions. Except in strictly loop-based copies, since it can move more data in the same sliver of time, especially if you utilize ported memory.
- marcodiego 4y ago
  > Sega didn’t do it in the SMS/GG for the same reason Nintendo didn’t do it in the GB or GBA; because those architectures were much more efficient at ferrying data due to their high cycle counts. I'm still unconvinced. I wonder what could be done with that spare cycles and what the video hardware could do with a dedicated bus with a full address space all for itself.

JohnBooty 4y ago

God, yeah. It's very difficult for me to look at retro game hardware design decisions without obsessing over "what if?" scenarios. My favorite (and by that I mean, "most agonizing") what-if's concern the Genesis/Megadrive. I don't have handy links, but: - There was some sort of hardware fail that prevented clear sample playback. The sound chip could play back crystal clear samples but in reality, this was impossible to achieve thanks to some issue (DMA? bus? something?) and in reality, sampled sounds on the Genesis sounded like butt - The Genesis' limited color palette and number of onscreen colors relative to the SNES and even the TG16 was kind of painful. I remember reading that one reason for this limitation was the need to include backwards compatibility with the SMS in the Genesis' video chip -- a feature few if any cared about or used. Arrrrgh. A Genesis with color to rival the SNES/TG16 would have been such a fearsome beast.

deaddodo 4y ago

> Nintendo also had something I think is a great idea when developing the NES: the video hardware had its own bus to the cartridge. This probably saved many cycles keeping the processor busy with other things instead of transferring content to the video RAM. It also allows better use of the system's very limited RAM and video RAM. Nintendo did this because they had to, not because it was an ingenious innovation. Sega didn’t do it in the SMS/GG for the same reason Nintendo didn’t do it in the GB or GBA; because those architectures were much more efficient at ferrying data due to their high cycle counts. The Z80, for the most part, at 4MHz is about equivalent to a 6502 at 1MHz due to architectural differences / differing design decisions. Except in strictly loop-based copies, since it can move more data in the same sliver of time, especially if you utilize ported memory.

marcodiego 4y ago
> Sega didn’t do it in the SMS/GG for the same reason Nintendo didn’t do it in the GB or GBA; because those architectures were much more efficient at ferrying data due to their high cycle counts. I'm still unconvinced. I wonder what could be done with that spare cycles and what the video hardware could do with a dedicated bus with a full address space all for itself.