Slot Expander:Will this work?

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Van Lord_Zett

Paladin (807)

afbeelding van Lord_Zett

01-01-2017, 21:25

not all m s x got busdir

Van l_oliveira

Hero (534)

afbeelding van l_oliveira

02-01-2017, 02:21

Lord_Zett wrote:

not all m s x got busdir

But all cartridges should drive it in order to prevent compatibility issues.

Van blackmsx

Expert (77)

afbeelding van blackmsx

30-01-2017, 17:16

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...

Van Albert Pieter Dotinga

Resident (39)

afbeelding van Albert Pieter Dotinga

30-01-2017, 21:59

Who was looking for the telcom modems i found abouth 6 of them....

Van RetroTechie

Paragon (1563)

afbeelding van RetroTechie

31-01-2017, 12:30

l_oliveira wrote:

But all cartridges should drive it in order to prevent compatibility issues.

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).

Van Gregory

Master (198)

afbeelding van Gregory

25-09-2017, 16:27

blackmsx wrote:

Last year I came across this schematic on a french MSX forum:

Since I will have some free days this winter holidays I thought I might try to build it.

Will the design work?

How do you switch between the 4 slots? So if you have cartridge in each slot, how can you select the one that needs to run?

Van alali.ahmed.t

Expert (72)

afbeelding van alali.ahmed.t

13-06-2022, 03:41

l_oliveira wrote:

Less chips, less wires to solder, works exactly the same:

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?

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