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Retro USB in Reverse

This Retro USB conversion stuff is getting interesting. Last week I showed off my first working prototype of USB to ADB input conversion. After another week of tinkering, I’ve now got the reverse conversion working as well. I can use my early 80’s keyboard and mouse on my 21st century Windows desktop machine! It’s awesome, in a totally useless kind of way.

As entertaining as this is, I’m not sure it makes sense to include this feature in the final Retro USB design. While it’s not conceptually difficult to do the conversion in reverse, it complicates the software and hardware for a feature that’s basically just a novelty. It means a USB-B port would be required, along with some way of switching between it and the USB-A port that’s safe and idiot-proof. It also means the ADB port would either be a source of power, or a peripheral that needs to be supplied power. It’s not a huge problem, but it’s lots of extra fiddly bits to design and include in the hardware. I’m thinking it may be better to keep things simple and focus exclusively on USB-to-ADB, which would help keep the cost down too. Or maybe I could find a way to offer ADB-to-USB as an extra option for those who really want it.

Read 4 comments and join the conversation 

4 Comments so far

  1. George Phillips May 6th, 2017 7:57 pm

    There may be more than novelty value to those who want to run an emulator but with original keyboard/mouse hardware. Not that I have any idea how many people might be in that position.

  2. Tux2000 May 7th, 2017 1:45 am

    I would try to get away with a single layout supporting both directions, with mounting options for one or the other direction, and with two different firmware versions. This way, you either mount core and ADB-to-USB parts and flash the ADB-to-USB firmware, or you mount core and USB-to-ADB parts and flash the USB-to-ADB firmware.

    And because I’m paranoid, I would add one pull-down per direction to a GPIO pin so that the firmware can detect if it runs on a board with the correct direction.

    Depending on how much flash is available, I would consider using the same firmware for both board variants and switch direction based on the direction GPIO pins. On the other hand, if “too much” flash is available, I would switch to a smaller and cheaper microcontroller.

  3. RVK May 8th, 2017 12:49 pm

    I would look into both ways as well. Seems like more a time investment upfront, but in the long run would be well worth it and would help move more units. Since you are already in the thick of it, seems more efficient to continue. Everybody wins approach;) I for one, would love to use my old Apple ADB peripherals. Great work, keep it up! Great things take time.

  4. Scott Taylor May 11th, 2017 3:43 pm

    Keep in mind that when iMates show up on eBay they get snapped up for $30-$40, and all they do is ADB peripheral to modern USB computer. People still find this functionality useful, and I think a device that can do both would be fantastic.

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