Ah, got it; I was asking about switching it from the keyboard as the XR4 does, not a physical switch.
But if you're just talking about a small number of selections then tiny diodes would probably work just as well and not require any power. m On Sun, Feb 26, 2023 at 9:52 AM Brian K. White <b.kenyo...@gmail.com> wrote: > On 2/26/23 08:23, Stephen Adolph wrote: > > Brian, If I understand your comment, I don't think you need an IC to do > > rom selection. I think the DAR uses a rotary encoder. > > I understand that the dar uses a rotary encoder. > The slide switch needs the extra glue. > > I was responding to Mike's question "how does the bank select work?" > answer: gratuitous extra parts because I just wanted a slide switch. > > > > When I first saw the DAR, I wondered about that. I'm pretty sure I found > > the part at Digikey. Very good! > > Steve > > > > On Sun, Feb 26, 2023 at 3:51 AM Brian White <b.kenyo...@gmail.com > > <mailto:b.kenyo...@gmail.com>> wrote: > > > > Gratuitous use of another chip just for 2 OR gates to implement a > > 4:2 encoder. It's all less efficient and less practical than the > > dial-a-rom, in that the dar holds 16 roms and doesn't need another > > ic, and the dar programming connection is even simpler and more > robust. > > > > But it just amused me to have a direct selector without manually > > binary encoding dip switches because why not? And I didn't want it > > to require a tool to use either like a screwdriver. And of course I > > always want an open source option, and I'm not up to the task of > > coming up with an open source rex-alike but using a Lattice part and > > the open source toolchain. > > > > It's unfortunate timing but I had already started this at least 3 > > years ago but just never finished it. A non-working version has been > > sitting in that github since 2019. A few weeks ago I finally dusted > > it off and corrected my bonehead pinout error, dialled-in the > > programming connection so it works well (the holes are slightly > > closer together than the pins, and the pattern and amount of offset > > took some trial & error) and replaced dip switches with the slide > > switch & or gates. I had no idea the dar was in the works. Not that > > it would have stopped me, but I just mean to say this isn't a > reaction. > > > > It's no competition anyway because only a very few people ever build > > these diy-only things. I want them to exist so the option is there, > > but almost no one actually employs it. So this is not touching > > anyone's sales. Besides, *16* roms. And of course really it's even > > sillier when rex exists which doesn't even need a programmer or > > adapter to load it's, what, 30? slots? But for other platforms 4 is > > plenty. There's only 2 roms total for the 600 for example. Still > > leaves 2 free slots for hacking. > > > > I just added the browser-friendly render of the schematic to the > > readme so you can see the bank-select. > > > > -- > > bkw > > > > On Sat, Feb 25, 2023, 8:18 PM Mike Stein <mhs.st...@gmail.com > > <mailto:mhs.st...@gmail.com>> wrote: > > > > How do you select among the 4 images? > > > > On Sat, Feb 25, 2023 at 6:50 PM Brian K. White > > <b.kenyo...@gmail.com <mailto:b.kenyo...@gmail.com>> wrote: > > > > On 2/25/23 10:31, bir...@soigeneris.com > > <mailto:bir...@soigeneris.com> wrote: > > > Morning all, > > > > > > I just made this video live this AM. The DARs for the > > Model T computers > > > have sold out already but my friend is making more. > > > > > > In this video we take a look at the ‘Dial-A-ROM’ a spiffy > > new multi-ROM > > > for vintage portable computers. It was designed by the > > same guy who did > > > the Backpack drive. First, we’ll learn how to use the > > Dial-A-ROM with > > > the ROM images that come preinstalled on it. Then we’ll > > see how to add > > > our own ROM images if we so desire. > > > > > > *https://youtu.be/CejyLsI0HIw > > <https://youtu.be/CejyLsI0HIw> <https://youtu.be/CejyLsI0HIw > > <https://youtu.be/CejyLsI0HIw>> > > > > > > Jeff Birt (Hey Birt!)* > > > > > > > And for the diy-er, I finally vetted these last week: > > https://github.com/bkw777/Teeprom/blob/master/4ROM.md > > <https://github.com/bkw777/Teeprom/blob/master/4ROM.md> > > > > -- > > bkw > > > > -- > bkw > >
