Re: Another DIY ProFile emulator (but also: bridging 3.3V and 5V)

Wow! Very nice!

Love "The Other Lisa" and "Don't Retrobrite" stickies too in the video. :-D

On 08/12/18 13:10, Tom Stepleton wrote:
> Hi folks,
>
> Anyone who's read Dr. Patrick Schäfer's excellent IDEfile project page
> <http://john.ccac.rwth-aachen.de:8000/patrick/idefile.htm> knows that
> I tried to make a ProFile emulator about eighteen years ago. And yeah,
> I didn't finish it---it was a bit too much for a class project :-)
>
> I guess I never really gave up the challenge, though, because I've
> finally tried again, and this time I did it!
>
> It's really part of a larger goal, though. I'm pretty excited about
> using tiny single-board computers like Raspberry Pi to interface with
> retro systems and "fill in" for peripherals and missing hardware. The
> BeagleBone Black and PocketBeagle <http://beagleboard.org/boards> are
> especially exciting little boards, since their integrated SOCs have
> co-processors called PRUs that can do very precise digital I/O in
> software. Earlier this year, someone used this capability to make an
> ethernet gateway for talking to a Xerox Alto
> <http://www.righto.com/2018/01/xerox-altos-3-mbs-ethernet-building.html>!
>
> The problem is that most of these boards use 3.3V logic, while most
> old systems deal in 5V. So, you need an extra bit of hardware that
> does the voltage translation. There are a few classic ways to do this,
> but lately I've been intrigued by the TXS0108E and TXB0108 series of
> chips, which do bidirectional voltage translation without needing to
> be told which direction the signal at each pin is going! I was curious
> to know if you could design a voltage translation board around these
> chips that would be general---you could use the same board for all
> kinds of projects with fairly minimal changes.
>
> So, that's what I've tried to do, and my proof of concept is the old
> ProFile emulator again. Unlike last time, this time I had Dr.
> Schäfer's notes and all the archived docs on Bitsavers, and I couldn't
> have done it without those. I also assembled a UsbWidEx
> <http://john.ccac.rwth-aachen.de:8000/patrick/UsbWidEx.htm> earlier
> this year, which made testing and debugging much, much easier. Now
> that that's done, the thing seems to work pretty well. I haven't used
> it for too long, but it works with Office System versions 3.0 and 1.0,
> and also with the various backup and restore options provided by BLU
> and UsbWidEx. (I'd be really curious to know if it works on an Apple
> III.) It seems pretty fast, too---a little bit of a surprise since a
> big chunk of the code is just a Python script!
>
> This project was a lot of fun to do, and it gives me a lot of hope for
> making these sorts of hardware substitutes easier for hobbyists to
> build. I hope there are lots of applications where one quick solution
> is to get a PocketBeagle and a board like mine and whip up a
> replacement for a missing piece.
>
> None of this stuff is for sale, and I don't plan to go into the
> hardware-selling business, but all of my designs and source code are
> up on GitHub and released to the public domain. You can buy circuit
> boards from (e.g.) OSH Park
> <https://www.oshpark.com/shared_projects/51GWu9Kw> and make your own
> if you are OK at surface-mount soldering---the hardest part is getting
> those two TXS0108Es in place. If you do try it, just remember that
> everything about this is early beta at beast; I'm a software engineer,
> not an EE! :-)
>
> Here are links:
> http://github.com/stepleton/cameo
> http://github.com/stepleton/cameo/tree/master/aphid
>
> and here is a silly video if you want to see it in action:
> https://youtu.be/1nYteAcB7Jk
>
> Hope this is useful,
> --Tom
>
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