RetroChallenge 2022-10: The Map, a Spreadsheet, and a disk image...

I now once again have a map to use!  The black circle in the Atlantic is the starting position.  The open circles are all of the locations you can visit. (China, Japan, San Francisco, Washington DC, New York City, The Caribbean, England, Switzerland, Greece, Egypt and India.)  The black lines are "preferred" ways to go, and the pink lines are unnecessary loops, dead ends, and game-ending branches of the maze

I started with a printout of the image from the previous post, and played the game a bunch just to explore the map.  I also started writing down what items you can get from which locations, which I've condensed down into a google sheet which is available as I work on it here. 

I checked it against maps online, and it seems to be 100% the same as those.  I really wanted to make the map entirely by myself rather than using one from the 'net.

Once I mapped it out the entire thing, I re-opened Photoshop and added a new map layer, and reduced down the map to only the segments that I should use in the game... eliminating dead ends, unnecessary loops, and places that will just end the game. 

Last night I also played a bit, streaming to my BleuLlama account on Twitch, which was my first time doing that too.  I learned a lot about how NOT to do it, and things to improve for the next time I play... I also need to figure out how to get it to record the stream for later viewing. 

One of the snagging points was that my disk image for C64 of the game was corrupted, so I also had to track down another copy that worked.   I think I'll prefer playing on the C64 because after the game is loaded, the transitions are much quicker than they are on the Amiga version.

RetroChallenge 2022-10: Beginnings

 

Just to get started, I quickly mashed together a couple screenshots from the game, drew a grid and adjusted colors so that I had this map template.  Every possible place on the planet that you can move the robot to is here.  Most of these positions you cannot actually get to, but that's fine.  I printed out a copy and will run through the game, just to map it all out, without actually doing any of the "talking with spies" nonsense.  I know enough to avoid a certain area, but i'm gonna map out the maze there anyway. ;D

RetroChallenge 2022-10 : Hacker!

I've decided that for RetroChallenge 2022-10, I'm gonna finally win the game "Hacker" from Activision.  I will probably play it on an Amiga emulator on my modern laptop, perhaps streaming gameplay on my YouTube channel or my Twitch channel (which I've not set up yet.)  I'll send a tweet through on my twitter when I'm gonna stream or whatever.

The basic premise of "Hacker" game is that... well, you don't know when you start it up.  The only instructions included with it originally were "insert game disk, turn on computer"... that's it.  You have to figure things out, how to use the interface, everything, just by playing it.  I love this.  You have to navigate this robot around the earth, trading stuff from your inventory with various spies, to get all of the pieces of a shredded document.  Some spies will trade for multiple items and some spies will only trade for specific things, so you need to get it right.

"Hacker 2" had a similar concept, but it was controlling a robot inside of a building where you also had control of four video screens, four tape recorders, and a bunch of surveillance cameras to be bypassed.  It's a lot more complicated of a puzzle... for another time..

Anyway, I've loved the concept of this game since I first got it in the mid-80s for my Amiga. I got pretty far in it, but my map got thrown out or lost, and I never really returned to it.  So part of this will be recreating a map so that I can figure out where I am and how to get around in the maze of game... especially once the map disappears.

Additional update posts will be made here to this blogger thingy as I progress.

I'd like to solve it for the first time on my actual Amiga 1000 if possible, which is in storage/on display in my office right now, so I may need to do some quick restoration of it to get it running for this. ;D

I may also stream/do a run through of the game on C64 since I have that one set up and ready to go right now.

Hm.  It might be fun to solve it on every platform I have.  I also have an Apple IIc that's easy to set up... hmmm... :D

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

RetroChallenge 2021-10 intentions (RC2014 Projects Braindump)

Hi all.  So I've decided to settle on working on various RC2014-based projects for this RetroChallenge.  I have a few related projects that I'm kind of in the middle of and have set aside for various reasons... the primary of which being my "ooh... shiny!" reason, where I get pulled off existing projects to start something else thanks to my brain.  ;)

Most of my RC2014 projects are all intertwined so it makes sense to kinda work on all or each of them simultaneously...

Anyway, here's a few things I'd like to work on this month:

"Lego Brick" RC2014

This is my main RC2014 system.  The display on it somehow developed a weird glitch on it that looks like Lichtenberg lightning print.  

I have a spare LCD panel that I can swap into place, i just haven't done it yet.  

Llama Vampire-Storage system (LLVS)

This is my "storage over serial" system that I started working on in the past.  It basically uses something like ANSI escape sequences over your serial console to do disk accesses. It could eventually be used for other devices as well like network and printer access, reatime clock, GPIO, etc.

Eventually, it would be great to have the LLVS "type in" a BASIC program that is a simple bootloader that will load in a custom CP/M kernel with  LLVS routines, so that a super cheap (and slow) CP/M system can be booted without boot roms, CF card module, or any of that expensive stuff.  

Also to be included with this are tools that natively talk the LLVS protocol so that you can retrieve and store content to your host machine from "standard" CP/M systems.

Obviously this also requires a host/terminal side of things too, which is being implemented in python currently, but could easily be reimplemented in C/C++ to be compiled in with the Pi Zero Serial Terminal module, so that you can use the Pi Zero's SD card as your CP/M storage device.

RC2014 Pro Build

I have most of an RC2014 Pro kit around, and I'd like to build up the various parts of it including the backplane, compact flash storage, and so on, so that I can finally do a native CP/M boot up.  This could be combined with the LLVS above to allow for easy transfers to and from the CP/M system and your "host" system.

I have a few modules that I want to build up and test and experiment with... i've just never really dug in to work on it.

Llichen-80

Llichen-80 is a CP/M kernel-based system that takes my LLVS-based system a step further, and adds in the TMS-9918A video card as its main graphics display.  This could be used simultaneously with the standard terminal, or as a replacement to it.  I haven't quite figured all of that out yet.  

I plan on making a few CP/M programs that configure the TMS and download files from the mass storage device into it, for loading fonts, graphics, etc.  Or just to use it for console output.

For use with a single composite display, I also have an hardware video switcher (simply two relays with a digital gpio input) that could be connected to a digital out from the RC2014 or as a GPIO line from the Pi Zero on the Pi Zero Serial Terminal card.

I have some of the basics of this working, but nothing really solidified.

The Llichen-80 system consists of an RC2014 CPU, Clock, Pi Zero Serial Terminal cards, along with the TMS9918A video card.  The Pi Zero Serial card is set up with a PiZero W, and is not running the standard PiGfx kernel, but instead running linux, so that it can run my python terminal application, so that i can add in all of the LLVS code

RC2014 Mini / Micro Mods for CP/M

It's well known that by removing some components on these boards, you can use them as a standard CPU module when upgrading to a CP/M system... replacing the fixed RAM/ROM for the switchable RAM/ROM and so on.  But it would be nice to be able to simplify this so that the RAM/ROM on the RC2014 Mini or RC2014 Micro could be made to be switchable using a simple jumper to connect to the logic needed to do the switching.  Not sure that this even makes sense being that the Mini CP/M upgrade exists, but I'll be thinking about it...

RC2014 Peripheral and IO Switcher Traffic Cop Thing

This one is more of a musing about a new Z80 system architecture, but it could be prototyped using lightly modified  RC2014 modules.

I feel like a peripheral manager type of card might be useful for a new system... one board that has ALL of the logic for peripherals, to switch them on and off, so that peripheral cards needn't have this logic repeated on all of them.  Then it could be vastly simplified for chip count.  It could handle catching bus requests for reading/writing memory or port based io, and work it out to be a single enable/disable line to be run to your peripherals.  That way peripheral cards could be made much simpler, and more easily moved around in the RC2014 memory and IO space... perhaps even live while the system is running.  It would be easy to make it such that any peripheral could be moved to any address, enabled, disabled, etc. Hmm...

RC2019-10 - A102 project - The end of the month of hacking

The short version is that I was super productive on these projects this past month.  I didn't complete it, but I never realistically thought I would be able to.  I lost a week's worth of time, or so, prepping our yearly Halloween Hack (blog post soon)... not to mention losing some time to work on building my Lego Saab 900... (blog post soon too).
One thing I will say, is that by combining the projects together, I tricked my brain into quite effectively "being okay with" working on one project or another, by them all being part of the same project.  So I would say that the month was quite successful.


So Anyway, I'm going to first go through a bunch of goals for the month, for the RC challenge, and in general, and briefly discuss my progress on them at a meta-level.  Then I'll get more into details about the actual work.

Overview and goals

Raspberry Pi / Emulation

I wanted to get the Pi 3 configured and booting right into an emulated  Amiga/Amibian environment.  I got the pi configured with standard raspian instead of Amibian, since I wanted this to be more of a general use machine.  It'd be nice to be able to use it for firmware development of the LL530 as well as the machine that it's targeted for.

So the target changed on this, but it is complete for now.

LL530 Development

I wanted to have the LL530 (USB Interface to Amiga serial keyboards, Amiga/Atari controllers and mice) fully finished.  Although I did not finish the firmware this month, I got more done on the project this month than I had in the past 6 months.  However, I was able to test the DIN pinout to discover that it's backwards, so I need to rev the board for those...

I didn't fully succeed, but I was successful.... if that makes any sense.

RC2014 Integration

I wanted to have an RC2014 Z80 computer built in as well, that I can connect to via serial port, for doing RC dev work without an emulator.  This aspect sadly got the least amount of attention.  I have an RC2014 mini installed, connected to the serial port on the Pi 3.  I've rewired the connection twice now, and I still cannot get it to connect using this wiring.

I spent time focusing on the other aspects.  So... 25% success.

Integration / Battery / Monitor / Enclosure

Most of the effort this past month was in this area.  I wanted to have the entire thing as a finished unit; to be able to be brought to a coffee shop, pull it out, turn it on and use it wirelessly. I can do all of these things right now with it.

So I would say this aspect was completely successful... although It does need improvements, particularly with the screen.

Installing The Linux

I started with a base Raspian image from their site.  I had the Pi hooked up to a HDMI monitor with USB keyboard and mouse.  After using Balena Etcher to get the image onto an SD card, I booted the  machine up.  I went through the basic setup, and updates.

I launched raspi-config from a terminal window, and went through to  enable ssh, i2c, and serial.

Next I installed some useful software packages:

apt-get install screen fs-uae-launcher stella

I made sure that serial was enabled  in /boot/config.txt,

enable_uart=1

I use screen as my quick and dirty way to connect to the RC2014 which is wired up to the uart on the raspi per the diagram above.  The reset line is wired to GPIO 4, so i use this shell script to "hit the reset button":

#!/usr/bin/python

import RPi.GPIO as GPIO
import time

print "Resetting the RC2014."

# setup GPIO4 as an output
GPIO.setmode(GPIO.BCM)
GPIO.setwarnings(False)
GPIO.setup(4,GPIO.OUT)

# send LOW (reset) for 1 second, then restore HIGH (normal run)
GPIO.output(4,GPIO.LOW)
time.sleep(1)
GPIO.output(4,GPIO.HIGH)

print "Done."
# return to high-z state
GPIO.setup(4,GPIO.IN)

The Red and Green LEDs are wired to GPIO18 and GPIO12, and I can run this script to do a nice fadey display on them:

#!/usr/bin/python

import RPi.GPIO as GPIO
import time

red = 18
green = 12

GPIO.setmode(GPIO.BCM)
GPIO.setup(red,GPIO.OUT)
GPIO.setup(green,GPIO.OUT)

r = GPIO.PWM(red, 100)  # channel=12 frequency=50Hz
g = GPIO.PWM(green, 100)  # channel=12 frequency=50Hz
r.start(0)
g.start(1)
try:
while 1:
for dc in range(0, 101, 5):
r.ChangeDutyCycle(dc)
g.ChangeDutyCycle(100-dc)
time.sleep(0.01)

r.ChangeDutyCycle( 100 )
g.ChangeDutyCycle( 0 )
time.sleep( 1 )

for dc in range(100, -1, -5):
r.ChangeDutyCycle(dc)
g.ChangeDutyCycle(100-dc)
time.sleep(0.01)

r.ChangeDutyCycle( 0 )
g.ChangeDutyCycle( 100 )
time.sleep( 1 )

except KeyboardInterrupt:
pass
r.stop()
g.stop()
GPIO.cleanup()

I may rewire these, or wire up additional LEDs to the ones specified with the Amibian/UAE led indicators, which are defined as GPIO4 for activity, GPIO16 for "Power", and GPIO16 for a clean shutdown button.

LCD Monitor

For a monitor, I'm using a $10 3.5" composite monitor.  I had to do a few things to get it to work however.

I had to hack the power input so that it would run off of 5v.  These are made to be used in cars, so they expect 12v of power.  At the time I did this, there were examples of doing this modification on
other displays, but not this model.  I powered it up using 12v, then probed the outputs in the power supply section for a 5v rail... and I soldered a 5V input there.

Once I had done this, I connected it to the 5v power in the enclosure, and hooked up the video input from the composite output on the Pi 3.

One snag I hit though, is that it wouldn't work right, It would flash on when the Pi booted, but it wouldn't show the desktop. Testing the Pi with HDMI or a known working composite input worked just fine though.

I was trying all sorts of things, and eventually decided upon trying PAL  video modes instead of NTSC, and that worked.  I spent some time tweaking the overscan settings as well, to stretch the screen to fit.  I also noticed that the contrast viewing range was substantially better on the top side of the display, so I ended up mounting it in the enclosure upside down, and I flip the video in the pi's config too.

So the changes that all this amounts to for /boot/config.txt are:

disable_overscan=1
display_rotate=2

overscan_left=0
overscan_right=0
overscan_top=5
overscan_bottom=5

sdtv_mode=2
sdtv_disable_colourburst=0

framebuffer_width=320
framebuffer_height=288

Although, as you can see from the screenshot above, it's basically unreadable.  So I was able to get it to work, but any future development on this will need to be with a different display.  Something with at least 480 rows, so that Amiga emulation can be reasonable on it.

Combining it all, and the Future...

I spent a few evenings rewiring that keyboard which mostly works really well.  I'm using a 5000mAh battery and get an undetermined-but-better-than-my-old-iBook amount of time with it.

The display is garbage.  I'm currently looking into replacing it with an HDMI-based 4" Waveshare IPS display with an 800x480 resolution for about $40.  Surely that will require moving around hardware inside of this enclosure, and since the display is meant to piggyback on the Pi, I will lose my integration board.

Obviously, I'll need to install the Amiga emulator, Tandy 102 emulator, my Model-T-Shell, and the Arduino IDE so that I can continue development on the LL530

In short, I'm super happy with where things are now, it just needs some tweaks to get it to be usable as a primary system. :D

RC2019-10 Update 1: A102 Amiga/Tandy/RC2014 Frankenstein

The Enclosure

Since I had started working on this last year, the enclosure is partially completed.  I had removed some plastic ribbing prior to the RetroChallenge, and mounted both a Rasperry Pi 3 and a LL530 keyboard interface board inside of it.  That's about as far as I had gotten last year, so that's a good start. (pics in the next update post)

The Keyboard

I started out with trying to get the keyboard working.  This seems to be the most time consuming portion of the hardware at this point, and has the most question marks associated with it.

The big issue is using the Tandy 102 keyboard with a spare "two header" Amiga 500 keyboard "encoder" board.  I had toyed with the idea of perhaps just wiring up the row/columns to the Tandy keyboard's rows and columns, but this brought up some issues.  Obviously, the matrix would be different... ie; row 2 column 2 would be different keys on the two keybaords.  This would be fine as I could just change the code in the LL530 to convert the fakey-102-500 keycode to be the correct keypress.  I kinda wanted to use the LL530 stock though, so this meant rewiring the 102 keyboard.

The 102 keyboard has diodes at most of the junctions, and there were a different ratio of rows/columns. but I plan on ignoring those by cutting the traces on the board and wiring around them, ignoring them.

I measured resistance for each key on both keyboards.  The Tandy 102 keys ("Alps Mount Round Slider") came out at about 100 ohms when pressed.  The Amiga keys ("Mitsumi KPR Hybrid Switches") were 0 ohms (no resistance).  Could this be an issue with the custom Commodore key matrix scanner on the Amiga encoder board?  Only one way to find out... Wire it up!

I wired up a couple of the Alps keys to the scanner, hooked it up to my LL530 and tried it.  Turns out it all works great, so no worries there! I apparently picked "9" and the left spare key usually between 'left shift' and 'z', which apparently maps to a "section character" (§)

Next, I wanted to try to clean up the keys.  They seem to bind a little as you press them down, as the plastic tube is getting snagged in the mechanism. This is probably due to wear, dirt, etc.  I removed one from the board (four through-hole solder pins), and disassembled it carefully to see what I was dealing with.

The keys popped off using an official key cap removal tool... a pair of tweezers wedged under the key.  Then the plunger and dome could be removed from the enclosure by flexing out the two T shaped tabs on the enclosure top. From left to right: the key cap, top cover (snaps on using the two large T shaped tabs), round plunger, rubber dome with carbonized contact, and finally the enclosure with the contacts in the bottom.


As far as I know, all of the keys are contacting/switching okay, but if i need to replace components, they're easy to swap in or replace the entire key.

I also took this opportunity to replace the "caps lock" and "num lock" keys, which are latching, with two spare keys, since I wanted to reuse the Num key for "right Amiga" and the caps lock key needs to be momentary for the Amiga matrix scanner. The pin layouts were different, so i needed to drill new holes in the board for the momentary switches. The switch labelled "56" above is the replaced caps lock, while "57" is the control key next to it.

Four of the "top row" keys of the 102 keyboard, the arrow keys, don't have quite the right snap/click that the others do, due to 30 years of use and wear.  I happened to have a bunch of exact replacements, which I got on ebay for another project a couple years back, "12x12x7.3mm Tact Switches"

Next is the task of remapping the matrix.  I found some commonalities between the two matrices, seen color coded above... the keys in yellow share the same x/y indexing with the Amiga layout, and the other colors only share the same column.  I traced out the schematic on the keyboard, and cut a bunch of traces.  Next up is rewiring it and wiring it up to the Amiga Encoder board.

More to come....

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

Llichen-80 (Retrochallenge 2019-03 Update)

I had originally intended for any time I could devote this month to the 2019-03 Retro Challenge was going to be for a new version of my RC2014 Z80 computer emulator, adding support for the TMS9918A video display chip.  But my plans have changed.  With the recent advancements with The 8-bit Guy's "Commander X16" 6502 computer, I decided to start reviving a project I was considering for a while.  The great thing is that there's so many aspects to it that it's like a grab-bag of things to do.

The original idea was to sit down with a C64, floppy drive, monitor, joystick, mouse and reference books, and start with BASIC, writing a text editor, assembler, IDE, etc and work my way up to having a windowed operating system like GEOS with a few utilities and such.

Except now, the spec of the system is designed by me, and I'm building that too.... Which meshes in perfectly with my original intention to build a RC2014+TMS9918 emulator, which I can use for initial development, and kickstarting the boot rom onto it.

Hardware

I wanted some sort of related name for the project, so I was thinking Llama, TMS, which became Llitmus, like the PH sensitive dye.  I was gonna go with Llitmus-80 with the '80' because it uses a z80, but then once I read that the litmus was made from lichen, I just went with the name Llichen-80.

First, let's get into the Llichen-80 system specification.

• RC2014 backplane/base system
• 7.37 MHz clock speed
• 32k RAM from 8000-FFFF
• 8k BASIC ROM from 0000-1FFF (*)
• 32k RAM from 0000-7FFF (*)
• Digital IO board at port 00
• TMS 9918A video board at port 10,11
• ACIA Serial port at 80
• ACIA Serial port 2 at C0 - connected to CH376S USB drive interface

So (*) Indicates something... there's an overlap of these two items. My existing design piggybacks bit 0 of the output from the digital board to select which of the two of these that memory READs come from.  That is to say that writing 0x00 to the digital out board will select ROM, and 0x01 will select RAM.  Writes to these locations always go to RAM.  So one way I can test this is:

• Start up the computer
• select ROM bank
• Write a basic program to peek from the ROM and write to the RAM
• select the RAM bank
• Yank out the ROM board, and everything still works fine

10 OUT 0,0
20 FOR A=0 TO 8192
30 B = PEEK(A)
40 POKE( A, B)
50 NEXT A
60 OUT 0,1
RUN

This all works great!  One addition I made was to intercept the VCC to the RAM chip and have it also connected to some CR2032 batteries for a backup.  It's not perfect, but it works well enough for my system for now.  I also added a switch to force the use of the ROM, since sometimes the bank switching can get into a messed up state and you need to force reboot off of the ROM.

The other thing I created was a second ACIA serial port, essentially duplicating the circuit of the stock ACIA serial port, but changing it to look at ports C0 and C1 instead of 80 and 81.

The TMS could be configured for anywhere, for the most part, but the ACIA chip IO port mapping is messy so they consume essentially from 80 to FF.  I went with the SORD-M5 configuration of putting it at 10 and 11h.  Although there might be issues with this...

Anyway, more about these modifications and such at the end of the month.

Experiments 

I ended up reassembling my RC2014 system, and started working on testing out the configuration.  I Was able to write a few BASIC programs to output to the video chip and to a TV I had hooked up, as you can see in the photo above.  I was noticing some weirdness though. The LEDs on the IO board were flickering when I was doing writes to the TMS, so I may need to move the port around to another location. I think I'm gonna go with the MSX setting of 98 and 99h.

I also became very aware that I do not yet understand how to get the chip to do what I want.

Emulation

I was going to write the emulator using QT Creator for maximum portability, and also using the Z80 emulation core and frameworks I created for my existing RC2014 emulators.  But recently, after thinking about it for a little bit, I realizes that 90% or the emulator I need is already out there and already very well supported.  MSX.

There was really no need to get a whole video display system working with my existing emulator when I could start with an existing, debugged, well supported emulator, openMSX, and just create a new hardware profile for the RC2014 with my system's configuration... and with some changes to support my bank switching hardware and such.

I made a branch of openMSX on github to handle any/all of the changes I've made for it, which at the moment is just getting it to build on OSX/Darwin 10.14 correctly.

I also was messing around with my good old friend, the Texas Instruments TI-99/4A as it uses the TMS9918 chip. I figured that I could experiment around with how color and graphics look.  I'm not a fan of the TI's font, nor the MSX's font for that matter, but I figured it's a good platform to get reacquainted with the weirdness of the TMS and to see how this all might look in the future, perhaps.

This is of course just a screenshot from the impressive web-javascript TI emulator at js99er.net.

More as it develops...

RC2017/4 Update - ObeseBits is now online!

I've not gotten more images done yet, but I have exported the tool "ObeseBits" to the interwebs.  You can play with it here:

http://umlautllama.com/p5/ObeseBits/

Press 'I' (uppercase) to pick a different image, 'G' and 'g' to change grid mode and settings, drag the mouse to move around in the image, and shift-drag to adjust the size of the grid.

I made it in Processing 3.3.1, in "JavaScript Mode".  When I got to this point, i just copied the entire directory to umlautllama.com, and there it is!

Enjoy!  Or dont! Whatever!

State of the RC2016/10

RC2016/10 is a little more than halfway over... so where am I?

Pretty much in the weeds.

I'm almost at the point where I wanted to be at the beginning of the challenge. I'm still working on finishing up the SD loader routines.  Well, I've finished the SD/Micro side of things (in the SSDD1 module - Serial SD Drive) both for the real physical drive as well as for the emulator, for loading only.  The emulation also supports writes now, and both support file/directory manipuations:  Directory listings, make directory, remove directory/file. (For the FAT filesystem anyway.)

I've got a bunch of things on my plate right now, between work, finishing up a contract or two, the animatronic bird project has reappeared a bit, plus time for the family, lack of sleep, and general lack of motivation for anything.

I haven't done any of the sector IO stuff yet, as I want to get regular files working.

In any event, here's a quick bullet summary of the current state of the project:

Done:

• Hardware for SD interface
• Hardware for ROM/RAM switcher
• SSDD1 process design (see image above)
• SD drive (SSDD1) firmware (preliminary)
• SSDD1 emulation for file and directory support
• SSDD1 firmware for directory support and file reading
• CP/M research to figue out what needs to be done, prior work.

ToDo:

• SSDD1 firmware for file writing
• SSDD1 firmware and emulation for simulated sector IO
• Z80 SSDD1 decoder (Hex string+checksum to proper formatter)
• Z80 IHX decoder (stream from SSDD1 to RAM writer

Gameplan tasks (Roughly in order of probable completion):

• Z80 IHX decoder
• Load a ROM from the SD card into RAM, switch off the boot ROM, restart, run from RAM
• Backport emulation into the firmware to get them equal

From here, I can go down one of two paths.  I can completely flesh out the rest of the SSDD1, and get the sector IO code implemented, which is probably the best course of action, just for completeness.  Or I could start working on porting/implementing the CP/M bios ROM, which might give me the "win" kick that I need to get the Sector interface implemented... although once I have the regular file IO stuff done (which it is) the sector IO stuff is the same plus a bit more wrapper implementation... after all it's just a bunch of 128 byte files in subdirectories... so...

• Sector IO SSDD1 emulation
• Backport Sector IO to SSDD1 firmware
• CP/M Bios
• CP/M Bootloader into LLoader ROM
• Burn new LLoader ROM to 27C512 EPROM
• Boot a RC2014 to CP/M!

RC2014/LL and RC2016/10

The RetroChallenge is upon us again!

This time around, I plan on working on my Z80 homebuilt computer, the RC2014.  (Website for RC2014, Order a RC2014) For a few months now, I've had my RC-2014 computer built, and modified to be an RC2014/LL computer. What this means is, is that I have some modified modules using no additional external hardware.

The above picture shows my RC2014/LL system with its extra RAM module, and the C0 Serial expansion board to the left, with the SD card interface board (SSDD1) on it.

The basics of this design:

Unmodified RC2014 modules:

• Z80 CPU module
• Clock module (* see below)
• Serial console interface
• RAM module (for RAM in the range $8000 through $FFFF

Modified RC2014 modules:

• Second RAM module
• ROM module
• Digital IO module

Additional hardware:

• Second ACIA Serial port at $C0
• SSDD1 (Serial SD Drive)

(*) While the clock module is unmodified, it technically is modified. I have added a 10 uF (50V) cap between the reset line and ground to be a quick-and-dirty power-on reset circuit. It works perfectly.  Every time I power on the computer, it "presses the reset button" for me. ;)

The plans to mod these parts are available here.  This is currently fully functional and tested. The modifications use unused gates on the boards, so that it requires no extra additional hardware or boards to implement. The basic theory to the /LL modifications are as follows:

Bit 0 (0x01) of the Digital IO module is tied to one of the extra bus lines on the backplane.  Let's call this "Extra-A".  When you do an "out" to that port of "0x01", it will trigger the Extra-A line.

The ROM module "out of the box" is configured such that if there is a memory access, which is a read from address $0000 through $7FFF, it will enable the ROM, and it will put its data on the bus.  My modification adds in one extra condition to this.  It adds in that only if the Extra-A line is LOW, that the ROM will be enabled.  This means that when Extra-A is 0, the ROM works. When Extra-A is 1, it's as though the ROM doesn't exist.

The RAM module "out of the box" sits at the high half of memory space ($8000-$FFFF), and is always enabled on memory READ or WRITE to those addresses.  The modification to this module is threefold.  First, it sits the RAM at the low half of memory space ($0000-$7FFF). Secondly, it is set up that WRITEs to this memory space will always work, regardless of Extra-A.  Thirdly, it is set up that READs to this memory space will ONLY work when Extra-A is HIGH.

The end result of this is that when Extra-A is low, reads in the low half of memory will come from the ROM.  When it is high, reads will come from RAM.  Writes ALWAYS go to RAM.

This is quirky...

I admit this.  It means that you can (and I will) write a bootloader/monitor ROM that is enabled on power-on, will read from a mass-storage device and write into anywhere in RAM... It can load a 64 k byte memory image into RAM, and then switch off the ROM and it will all work.  The quirkyness is that you cannot verify the loaded-in memory in the low range of ram, since reads will come out of the ROM.   Obviously, you also need to do this routine completely out of registers, as your stack variables will get overwritten if you're not careful.

Anyway....

If you want it to behave like a stock RC2014, remove the jumper from the IO board to Extra-A, and instead add a jumper from ground to Extra-A.  I have added a switch to mine to force this in the case where the IO board comes up in the wrong state.

Additionally, I have added a second serial port, which basically follows the circuit for the first port, but it sits at $C0, and does not have an interrupt line wired to it.  The RX/TX on that one comes out to a FTDI-like pinout header, which is where my SSDD1 module plugs in.  The plans for this serial port are available here, and can be seen as the brown perf-board on the left of the topmost image of this post.

The SSDD1 module...

The Serial SD Drive module is the mass storage module that I've created for my Z80 to interface with. I know that I can push the FAT filesystem support onto the Z80, but that would require substantial effort.  I instead decided to go with the model where I have a smart serial-based device that you tell it "i want this file" and it sends it out.  Like a local BBS. ;)

The use of a serial-driven drive is not unprecedented.  It's somewhat modeled after the Commodore 64/Vic 20's "IEC" serial interface for floppy drives.  It also mirrors it in that the drive has some smarts in it to deal with the drive architecture.

I also went this route for the ultimate form of this computer, which is to run CP/M.  CP/M expects drives with a Drive+128 byte Sector layout.  While other Z80-CP/M computers implement this by having direct interface to the sectors on the spinny disk/cf/sd card, I will do it by having files on the SD card, for the most amount of flexibility.  There will be a "drives" folder on the card containing folders named "A", "B", "C", and so on.  These letters are the drives.  In each of those will be directories for the tracks, named "0000", "0001", etc and in each of those, files named "0000" "0001" "0002" etc. These files are the simulated sectors on the disks.  It will be easy to build virtual drives for other use out of this.  It also means that I won't need some special interface on a modern computer to talk with this.  I won't have to do 'dd' style transfers to get at the data... It's all just sitting on a FAT filesystem.

The implementation of this module is based on an Arduino with a microSD breakout module.  The serial interface communicates directly with it, and it sends the content via serial back to the Z80 host.

The above picture shows the SSDD1 module off of the RC2014/LL expansion board, and instead wired to a breakout board where I have a second FTDI serial-USB interface so that I can debug the hardware more easily.

And that brings me to the current Retro Challenge...

My goals for this month is to do a few things here, to finish up this computer system...

• Finish up the firmware for the SSDD1
• Sector load/save support
• File load/save of intel hex files
• directory create, list, remove
• Write the SSDD1 emulation for the emulator
• Finish up the loader and burn it to a ROM
• Write a CP/M bios that uses the SSDD1 interface
• Build CP/M disk/sector files 
• Play Zork

Stretch goals:

• Extend the NASCOM BASIC to support the SSDD1 for loading and saving.

The RC2014 Computer: 1. Emulation

As you may know, I'm bigtime into Z80 computerey stuff.  For the past 20 years or so, I've been hacking Pac-Man ROMs, been maintaining the Ms Pac Disassembly, and have made my own Z80-Pac based programes over the years.

Fairly recently, I got a Kaypro II from a friend at interlock, and it worked perfectly, and looked brand new.  I felt like I couldn't hold on to it... "it belongs in a museum!" ...so I donated it to ICHEG/Strong Museum of Play.  But it helped whet my appetite for a CP/M computer.

Another project I've been wanting to do was to start with a Commodore 64 (I know it's not Z80, it's 6502ish), a floppy drive, some blank disks and a hardware manual and code up, from scratch, an OS.  Start out by making a text editor, assembler, GEOS-like GUI, etc.

These projects recently had an opportunity to overlap, and they all seem to converge on the RC2014 modular Z80 computer.

The RC2014 computer is a backplane-based modular computer created by Spencer Owen, based on the Z80SBC by Grant Searle.  There are modules for the CPU, RAM, ROM, Serial Terminal interface, and so on.  It is available as a kit from tindie.com.  Once assembled, you hook up a serial terminal to it, power it on, and you get a 1980s-esque BASIC prompt onto which you can write your 32kbytes of program.  This is based on Grant's simplified Z80 computer, so there is no off-line storage.

My general plan for the RC2014 is:

1. Emulation:
1. Create an emulator for the system to aid with rapid development
1. also bring my "bleu-romtools" from Google Code to github
2. Add a serial-based storage solution to the RC2014 emulation to confirm proof-of-concept
3. Add ROM swap out to the emulation
4. Add 32k of ram to give a full flat 64k of ram to the emulation
2. Hardware:
1. Get a RC2014 kit
2. Build the RC2014 kit
3. Make a test ROM to run on real hardware to verify my toolchain is working
4. Create a new serial card that sits at port 0xC0 (second serial)
5. Create the SD Drive firmware for the serial arduino
6. Hack the ROM and Digital IO boards to allow for disabling the ROM
7. Add 32k hacked RAM to the system
3. Name: RC2014/LL
1. At this point, the architecture is different enough and well defined enough that I think a new name for this configuration is in order. I call this configuration "RC2014/LL".
4. Port CP/M
1. Create the BIOS
2. Create the sector-based emulation layer in the SD drive
3. Boot CP/M
4. Play Zork

I started out by making an emulator using the Z80 Pack emulation system.  Once I got this running, I realized the limitations of this emulator and looked around and found another emulator that suited my needs better. (I wanted a way to "swap" memory around, which Z80 Pack would not do in a way that wasn't a major hack.)

I created a layer that adds disableable memory regions, and added emulation of the 6850 ACIA serial chip, and threw the 32k RAM BASIC ROM at it, and it started right up, running BASIC!

I added a second 32k of RAM (easy to do when you're emulating it!), and started creating the SD interface, also using the 6850 ACIA for communications.  I then added a port, emulating the IO card, on which bit 0 (0x01), when set, will disable the ROM... So any reads to the low area of memory will read from the ROM.  Whether this is set or not, all writes to that area of memory will actually happen to the RAM... they will just be hidden from reads until that bit is set.

I now have the basics of the RC2014/LL system emulated in software!  I created a boot/diagnostic ROM which can be used for all RC2014 systems which can probe memory to determine type (ROM, RAM, unpopulated), peek and poke memory, In and out IO, and other utility functions for the SD card interface.

Currently, I'm writing the SD card API which I will port to the Arduino Leonardo and SD breakout board which I have ordered, once those come this weekend, I'll shove them into my own serial board and burn a test ROM and see how it goes....