Slot Expander:Will this work?

not all m s x got busdir

Thanks for the answers! I've been away for some weeks and I just saw your replies.
I've been trying the first circuit I posted here without success.

I'll try the one you posted to see if I can get it to work...

Only cartridges that implement IO port(s), that you can read from. Write-only IO port = no /BUSDIR processing needed as MSX puts any data buffers (if present) in MSX inside -> cartridge slot direction. And with regular memory r/w, the MSX handles this also. For IO ports this is more difficult (if not impossible) since there's no way of knowing if or which IO ports are implemented in a cartridge. Hence in those cases cartridge has to signal data direction as needed.

But a slot expander should ALWAYS process the /BUSDIR signals produced by cartridges in the expander. If it doesn't, then it's incomplete (read: regard as non-functional). Only exception here is if there can't be readable IO ports inserted in the expander (like in the case of an SD interface / mapper combo that expands a primary slot but uses the subslot signals only inside the same cartridge).

I am trying to use this cirucit to expand my Yamaha YIS-503II (similar to CX5M schematic). I know people will say "but it is expanded) I still want another slot expansion for another project I want to perofrm. The questions are:

if I want to expand it on slot 0 what would be the SLTSEL ? Can I use the full chip of 27C512 if I expanded on Slot 0?

I was going to ask about the RESET but I noticed that Z80 has a pin for RESET already.

Finally, is there a gerber file for this project? or a similar one?