Handheld RC2014 System (RetroChallenge (sorta))

One of the great things about making stuff is that you can make stuff that doesn't yet, or shouldn't exist.  

I honestly didn't get anything done on my RC2014 projects for RetroChallenge this year, other than an idea, and some 3D printed stuff within the final few days of the month.

I've had it in my head for a while to make a gameboy formfactor RasPi system for a while now, even though I already have a portable Pi emulation system in my Atari Lynx enclosure.  So I found a model for the "super retropipod" enclosure on Thingiverse and printed it out, and ordered and then modified a 3.5" lcd and shoved it all into the case.

I decided i didn't want to make a PCB or hack up a perfboard to support tact switches, and I had a bunch of largeish 12mm tact switches, so I modeled and 3d printed mounting boards for those too.

Then I had an awesome-horrible idea.  I would mount a RC2014 inside the enclosure as well!  If I managed to make the enclosure a little thicker (about 1cm) I could easily fit a RC2014 mini or micro inside the case along with the pi and all of its fun stuff.  I could even probably also fit in the TMS9918A video card piggybacked onto it inside the enclosure.  So I modeled and printed out the thickness extension too!

Long story short, I have the beginnings of my ultimate multipurpose Pi/RC2014/Llichen-80 handheld!  And she's a chonky beast too!

I modeled and printed a piece to sandwich between the layers of the "pi-boy" enclosure I printed, and added a space for a nice switch for power on the side.  I still need to wire it all up, but I'm on my way to having this thing be AWESOME!  

Although I still want to make a "tall-boy" at some point... take two GB DMG enclosures, and extend the screen space to be taller, and put in a rotated, vertical monitor in the space there.  eg, use a 4" or 5" lcd in portrait instead of a 3.5" in landscape...

Next actions on this project:

• Wire up the buttons to the GPIO header
• Wire up the LED on the front panel to the GPIO header
• figure out a power solution for the system (batteries, recharging, etc)
• Mounting solution for RC2014 inside the enclosure without it moving around
• Make a 2-board backplane for the RC2014 so I can also have the TMS board internally
• Wire the TMS to the monitor too, and figure out a quick way to switch inputs... perhaps two NC momentary buttons that disconnect the monitor from each of the two inputs, so it will auto-switch to the other input. (or short the input to ground via 75Ω resistor?)

Links:

• Super Retropiepod enclosure
• Retropiepod enclosure extension and tact switch mounts
• GPIOnext (formerly GPIOneer) software to use GPIO inputs as keyboard presses

RC2019-10 - The Globbing Of The Projects... Globjects?

Hey.  Long time no post.  How y'all doing?  I'm still here. I've gotten a lot of small things done over the past half year, and a lot of things almost done as well... and some long-standing projects not done too.  So, I've been almost productive...  Anyway, I hope to try something different this month for the RetroChallenge RC2019-10...  Let me explain...

The main projects I've been trying to work on recently are:

LL530 USB interface for Amiga serial keyboards and controllers

I've been poking at it a little over time, and am really damn close to getting the proper firmware done for it, but I just haven't finished it.  Which is stupid because I can actually sell these things once I'm ready!  I have keyboard working for all but my A1000 keyboards, and I have joystick/mouse/paddle working... but not at the same time in a way that I'd be proud of.  I also will eventually need to rev the board to fix three layout issues; a power/ground short, lack of ICSP programming header, and lack of pull-up resistor for VCS paddle sampling.

Llichen-80 Computer (LL80)

Okay, so it's not really a whole other completely new computer... but it is a specific configuration of the RC2014 Z80 computer.  It started out this year as a whole lot of customizations to standard (but old, obsoleted) RC2014 boards to add bank switching, using the 8 bit parallel IO board (the one with all the LEDs and switches!).   Now, I reworked the idea so that I just use the standard "Switching ROM" board and the "64k RAM" board.  That simplifies the design; making it easier to get to the LL80 spec, since just using those two cards replaces two RAM boards, one ROM board, and one IO board... plus no modifications to any of the boards are necessary.

The other part of the LL80 computer is the "LLSuper" board.  This is an arduino-based supervisor of sorts that sits on the serial console port.  It acts as your usb-serial interface for when you use a desktop computer as a console.  This board used a CH376S USB Drive interface to access any flash drive as mass storage (it's a neat part.. like $2 for a board with a USB A port... it talks TTLRS232, SPI or parallel, and handles all of the disk switching, FAT filesystem etc. So there's very little overhead on a tiny ATmega micro.  I also have an I2C based clock chip board for this.  This sits between your console and the RC, and lets you have a kind of shell access to the disk from the console, as well as from the RC.  The RC side of things also got direct access to virtual disk image files with a sector-based interface, as well as direct fileio...

The next steps would have been to write a CPM BIOS and make the thing boot into that.

But I've come to realize that even the LLSuper board is unnecessary.  I can accomplish near-similar things using the standard  "Pi Serial Console" board.  If i use a RasPi Zero, and boot linux on it (or adapt the code in the PiGFX kernel, I can put in my serial-disk IO stuff, for cheaper, without needing to fab up my own board.  I started to mess around with this using my new RC2014 Micro, a Pi Zero, and a slight hack to attach the reset line of the RC to a GPIO of the Pi, so i can now reset the RC from the Pi.

I do have the protocol all worked out for the serial interface using unused ANSI escape codes, which are made for custom purposes like this.

A102 - Portable Emulated Amiga in a Tandy 102 shell

This is one i've wanted to work on since last year. I was trying to get it done before Rochester MakerFaire last November, but burned out on it.  It essentially is a project that joins together a bunch of parts... all of which I have:

• Raspberry Pi 3, with Amibian... booting right into an emulated Amiga environment
• Tandy 102 shell, rescued from some unrepairable 102's
• Tandy 102 keyboard, also rescued (keys bind as they're pressed though)
• Amiga 500 keyboard interface board, from a long-gone computer
• My LL530 USB serial keyboard interface board
• Amiga mouse
• 3.5" composite LCD panel (new, $10 online!)
• large Power Bank battery pack

This project entailed hacking the keyboard (removing the wiring/traces on the board) to convert the scan matrix to match an Amiga 500 keyboard.  This gets connected to the LL530, which is plugged into the Pi.  All of it gets jammed into the 102 shell, and becomes a portable computer. 

I waffled a bit on this... mainly because the keyboard stuff would be a chore.  I want to remove every key, and clean their travel tubes, to eliminate the keys binding.  Wiping out the traces and rewiring the board seems like it's going to be a tedious process... So i kept thinking that maybe I should make a cherry-mx switch based board to fit the keyboard space instead... and... yeah... i just kept going down that same path of "maybe i should do this other thing" instead... instead of actually moving forward on any of it.

I also pondered putting the entire Llichen 80 computer into this shell... which brings us to...

RC2019-10!

So that's where RC2019-10 comes in.  Why almost fail at three projects when I can almost fail at ONE project! Seems a lot more efficient!

The end result for this month will be to have a working portable laptop computer that runs Amibian (Linux), RC2014 (via serial connection to the Pi) and general Linuxy stuff.

Or, more granularly, here are the tasks as I see them now: (in no particular order)

• Finish the Keyboard + Joystick/Mouse firmware for the LL530
• remove the wires on the 102 keyboard PCB
• clean the travel tubes on the keyboard
• rewire the keyboard to match the Amiga's matrix
• Wire the keyboard to the Amiga 500 interface board
• Connect the RC2014 Micro via the Pi's serial interface pins
• Additional buttons on the device to cleanly shut it all down
• Have it all powered from a 5V/USB powerbank mounted internally
• Serial-console textmode app for Linux that provides the beginnings of a backchannel to 

Stretch goals:

• Full drive interface for the RC2014
• CP/M BIOS for the RC2014 that uses the serial protocol
• Fit the RC2014 Mini + 64k RAM + switching ROM + TMS9918A cards inside the case
• Have the video switchable between the Pi and the TMS9918A video card

Not sure how far i'll get, but it globs together all of the recent projects in a way that I won't feel like I'm neglecting one project by working on the others... since they're all the same project now. :D

My all-in-one Pi

I have a Raspberry Pi, but I wasn't sure how to encase it or whatever.  I picked up a bunch of these 13" LCD monitors from the scrap heap at work.  They run on 12v, and have VGA, S-Video, Component and Composite inputs.  I figured that I wanted to use one as a display for the Pi, so I started with trying to suck 5v of power off of the mainboard inside of it.  After a little probing with a multimeter, I found a 5v and Ground that seemed like a good place to tap.

I sacrificed a micro usb cable to tap directly onto the motherboard.  On the left you can see where I zip-tied it to the frame to prevent strain on the soldered connection.

The cord comes out from an unused port opening.  I added the two screw/standoffs you see on the bottom right.  I should note that I also removed the fan whose grille you can see in the top of the frame.  The fan wasn't needed, and was super noisy.  Next thing to do is to mount the pi on the back of the case.

Huzzah.  Everything fits nicely.  A short composite cable to hook it up and it's ready for use... Only problem was a way to prop it up.  I was going to build some sort of stand for it, but after looking around the parts area of Interlock, I found a broken Dell monitor I had brought in months ago.  I decided to repurpose its stand.

I removed the plastic backing from the upper portion, then removed the mounting plate from the stand.  I added four more holes to line up with the four screws coming out of the monitor (which have a ball joint as seen above) and use those to mount it to the stand.

After assembling it all together, it seems to work nicely.  I've since zip-tied the power brick to the back as well, although I'm not sure I like the way that works out.  The USB and ethernet ports are underneath the stand.  I'm considering moving the pi to be on the back, along the right side rather than on the back along the bottom.

You can also see in the above picture that I have added in a handle on the side of the monitor as well.  It's just the same kind of wire/metal drawer pull as I've used in the past.  It adds a nice carry handle to the project.

All of the ports of the Pi are still easily accessible.