Switchable cartridge adapter?

[+slx]

I have one of @Dropcheck's original cartridge extenders for my 1200XL but due to desk space would prefer a vertical version (which is available in the meantime but sold out). I thought about designing one myself, preferably with two switchable cartridge slots. On first sight it seem rather straightforward with all the lines from the computer's connector going to a cartridge connector on the board. But how to disable a cartridge? I found a long discussion of adapters in this thread but don't get whether simply interrupting the +5V line is enough to disable a cartridge or if more is needed to prevent the unwanted cartridge from messing up things. 

[TGB1718]

Having a look at the circuit diagram, it looks like line S3 is used to select the cartridge, so it should be simple to

have a pullup resistor on the line of each "ROM" and use the switch to select which one you want.

[ClausB]

S5 selects an 8K cart. S4 and S5 select a 16K cart. Switch those high to disable the ROMs. Keep the 5V power on both carts.

 

S5 is pin 12 and S4 is pin 1 on the connector.

 

And for carts with other devices besides ROM, the select line CCTL is pin 15.

Edited October 16, 2022 by ClausB

[+slx]

5 hours ago, ClausB said:

S5 selects an 8K cart. S4 and S5 select a 16K cart. Switch those high to disable the ROMs. Keep the 5V power on both carts.

 

S5 is pin 12 and S4 is pin 1 on the connector.

 

And for carts with other devices besides ROM, the select line CCTL is pin 15.

So connecting pins 1, 12 and 15 to 13 should let that cartridge disappear for the Atari and removing the connection would make them active? Would that work at any time or just at power-up/warmstart/etc.? (Switching while running code on the active cart would obviously crash the system with high probability but would it e.g. work to swap BASIC for Assembler/Editor while in DOS? (Not that I'd need that, just curious.)

[ClausB]

4 hours ago, slx said:

So connecting pins 1, 12 and 15 to 13 should let that cartridge disappear for the Atari and removing the connection would make them active? Would that work at any time or just at power-up/warmstart/etc.?

No, don't connect them all together - bad for the computer. Add a pull up resistor to each select line, 3 per slot. Add a DPDT switch to S4 and S5, center poles to computer, and a SPDT switch to CCTL.

 

Depends on the cart, I suppose, wether it can be switched on the fly. Most probably cannot.