On 2/26/23 08:25, Stephen Adolph wrote:
sorry, Ignore my pre coffee comment. I understand now, you were taking about your design. Sheesh.
hah, well I am guilty of top-posting
On Sun, Feb 26, 2023 at 8:23 AM Stephen Adolph <[email protected] <mailto:[email protected]>> 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. 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 <[email protected] <mailto:[email protected]>> 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.-- bkwOn Sat, Feb 25, 2023, 8:18 PM Mike Stein <[email protected] <mailto:[email protected]>> wrote: How do you select among the 4 images? On Sat, Feb 25, 2023 at 6:50 PM Brian K. White <[email protected] <mailto:[email protected]>> wrote: On 2/25/23 10:31, [email protected] <mailto:[email protected]> 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
