74HC161 as a switch?

Discuss hardware-related topics, such as development cartridges, CopyNES, PowerPak, EPROMs, or whatever.

Moderators: B00daW, Moderators

Post Reply
proveaux
Posts: 87
Joined: Wed Feb 15, 2012 10:19 pm

74HC161 as a switch?

Post by proveaux » Wed Oct 17, 2018 4:13 pm

Can I use a PC74HC161P as a switch to either ground one board or another? If so, how would i wire it? Switch one on and the other off when there is a reset.

lidnariq
Posts: 9305
Joined: Sun Apr 13, 2008 11:12 am
Location: Seattle

Re: 74HC161 as a switch?

Post by lidnariq » Wed Oct 17, 2018 4:25 pm

Not by itself, no. You'll need some other part to convert the output from the counter into something that only enables one ROM or another.

yaros
Posts: 145
Joined: Tue Aug 28, 2018 8:54 am
Location: Edmonton, Canada

Re: 74HC161 as a switch?

Post by yaros » Wed Oct 17, 2018 5:45 pm

You can use multiplexer/demultiplexer for that. You should be able to wire both roms on one address bus, and use 8-16 bit multiplexer to choose data bus.

proveaux
Posts: 87
Joined: Wed Feb 15, 2012 10:19 pm

Re: 74HC161 as a switch?

Post by proveaux » Thu Oct 18, 2018 11:26 am

I have some 74LS139. Could they be used to make a switch or in combination?

lidnariq
Posts: 9305
Joined: Sun Apr 13, 2008 11:12 am
Location: Seattle

Re: 74HC161 as a switch?

Post by lidnariq » Thu Oct 18, 2018 11:43 am

Sure, in combination.

Details depend on exact details of what you're trying to do (e.g. one PCB with multiple ROMs, multiple preexisting PCBs, &c)

proveaux
Posts: 87
Joined: Wed Feb 15, 2012 10:19 pm

Re: 74HC161 as a switch?

Post by proveaux » Thu Oct 18, 2018 11:49 am

I wanted to wire 2 gameboy games to a super gameboy board and use the ground to select which one plays or that what I thought would work.

lidnariq
Posts: 9305
Joined: Sun Apr 13, 2008 11:12 am
Location: Seattle

Re: 74HC161 as a switch?

Post by lidnariq » Thu Oct 18, 2018 12:11 pm

Use the 74'139 as:

1- from the SGB, connect A15 ("/LOSEL") and /CS ("/HISEL") to the two half '139's /E inputs
2- from the counter, connect QA (the least significant bit output) to the two half '139's A inputs
3- from the '139, connect the /Y0 outputs to A15 and /CS on one cart, and the /Y1 outputs to the other cart

Configure the 74'161 to count up by one whenever the /RESET signal goes low

proveaux
Posts: 87
Joined: Wed Feb 15, 2012 10:19 pm

Re: 74HC161 as a switch?

Post by proveaux » Fri Aug 09, 2019 1:29 am

Thanks lidnariq!

Image

Post Reply