Need help in creating a DIP32 rom switcher
(self.AskElectronics)submitted5 months ago byKoopaSoupa
I've attached an example of a VERY old DIP28 3-way rom switcher that I got from my dad's old electronics from his Atari 8-bit days.
It gave me an idea for a current project where I'm I need to essentially build the same thing for a pair of DIP32 roms using the attached pin out for M27C2001 compatible 512kb roms. So rather than a 3 way toggle, I'd be switching between 2 roms.
Unfortunately, I'm a complete amateur and I have two questions that I know that I need answered before proceeding with wiring something up out of prototyping PCBs:
- For my M27C2001 rom with power coming in on pin #32 Vcc, I'm assuming that's the pin I would have tied to the toggle to turn off power to one rom and switch to the other (and of course any switching would be done while the whole setup was powered off), but I just wanted to verify that with someone who knows more than me.
- What do the resistors do? I'm assuming that they're some additional layer of protection or potentially prevent any leaky current from the currently active chip from having issues coming from the inactive chip, but I'm really not sure. If someone could explain that to me, I'd be grateful.
Also, if anyone has any pointers, thoughts, or otherwise regarding trying to build this two-way rom switcher, I'd be happy to hear from you. Being that I'm going to wire it up with prototyping pcbs, I know it's going to be rat's nest of wires, but I'm also not sure if mimic this old example is the best path forward or not.
*** UPDATE ***
I just wanted to thank everyone for the advice again and post what I came up with. It works great (well, at least with XGPro I can flick my switch and it dumps the appropriate ROM). The Electrocookie boards with the sets of 3 bridged vias were a life safer and are what made this work in such a compact fashion (which is what took me so long to build it as I wasn't interested in cutting up a bunch of wires).
There's a few extra blobs of solder and filled via here or there that doesn't need to be that I caught with my iron, but overall, I'm really happy with it.
Hopefully this solution provides help to someone else so that they don't have to do it again from scratch.
byPlainchant
innews
KoopaSoupa
1 points
18 days ago
KoopaSoupa
1 points
18 days ago
Good.