Atari 2600 Complete

Finally picked up the Atari 2600 again.  I found someone selling a unit with 100 games for $100 in town.  I managed to score it for $75 but it only actually had 60 games..  Still turned out to be 40(ish) games I did not have before. and Sadly that Atari did not work.  (Discussed with seller and we agree’d it wasnt an issue because the games were what I was after, but hey.  another to sort out right…)

however of course I want to be able to PLAY these games… I’m tired of emulators.  I took the WIP unit out of the box, re opened it and decided to finish it.  this whole thing really should have been like an hour project one afternoon, not sure why I shelved it.  But I wired the transister boost I built previously, gave it power, a game and turned it on.   wow… whats that nasty hum… oh wait, theres a short for sure!….

20 minutes and a ton of tests for shorts/etc later I discovered when I made the original circuit, I put the transistor in backwards… on top of that I for some reason put the ground on the video in and the video in to VCC.  not smart.

oh well.  disassembled that bit.  reversed the in and out lines so the transistor was correct, and tested again.

and Voila!  things are running.  Before looking at the photos, I KNOW I need to work on my photo skills and my phone is NOT a suitable camera.  I’ve previously liked the details of the mod I installed and how it works, so feel free to go look at that post here

if you have any questions or just want details, please feel free to reach out to me.  I can create a schematic and wiring diagram for anyone that isn’t satisfied with the link

And finally a horrible video of it working

FPGA CPU Design — DRAFT

when I was little I was always fascinated with how things worked.  and back in the TRS-80 days it was simple and clear.  well things have progressed GREATLY since those days, and its a lot less understandable to the base user these days.  you add this nostalgia to my wishing to flex my school knowledge some in the decades since and I came up with this…

So I started building my device using a program called Logisim I’ve had some issues loading the site lately so heres the direct download on Sourceforge.  once I started progressing with that I realized its not even USABLE.  short of manually setting the logic/etc and watching the output and using an excel sheet manually its not what I wanted.    so naturally I took the big leap into something I knew very LITTLE about which has the power to do what I want (realize the actual CPU).

So as much as this is me building a CPU and yes I will demonstrate every piece for you as I do this in logisim, I will also keep the FPGA code base up on GIT with it so you can see and learn with me.

First off, I do NOT expect this to be overly useful to anyone for anything real as it’s an old school 8 bit CPU, and I expect about as much power as the old Z80.  It will be nice to at least say “I DID IT!”  but who knows, maybe one of you will take the base learning and turn it into something real world with some actual power.

Now for starters.  the base of the CPU is going to be the ALU (Arithmetic logic unit)  and in my design i’m going to start it with the basics.  lets ADD something.

Watch for the next post where we start the actual work.

Compaq Portable III score.

So, every now and then I like to check our our local “good will” style stores.  Here in Ontario we have Value Village and the Salvation Army as well as a few others.  On these trips I often find some cool things that I take home, restore and resell or keep, but every now and then there’s something that you just cannot turn down.  This visit happened to be one of those visits.  I scored a complete Compaq Portable III.  No idea if it worked or anything, but for $15 CAD it’s worth the score.

I will be tearing it down and doing a complete restore, so keep watching for the Portable3 tagged posts.

Retro Pi

So one of the many things keeping me so busy these days is a large portion of people who really liked the RetroPie custom build I’ve made.  So I figured I would explain what all was done.

first bought a bunch of RaspberryPi 3s.  and various controllers as requested per user, then I took RetroPie flashed it to a card.  developed a remote admin and update tool.  once I had all that working it was as simple as printing the custom cases they wanted and hooking it all up.  however I ran into a small issue.  It seems the supplier I used for the Raspberry Pi’s used more than 1 source for the SD cards.  and some were 112MB smaller than the SanDisk I used.  why does this matter, well.  pulling an image from one, cannot be written to the other.  BUT thanks to some linux power and a little google, I figured out how to shrink the partition and truncate the image file.  then it was write the SD cards for them all.  from there just finish printing/assembling the 3D printed cases, get all my branding on, test and deploy.

The branding material was done up by my Friend at SignPros Design

all code built and 3D files will be uploaded on GIT once I get them cleaned up and usable.  There are a few photos below of the N64 build and the SNES controller for this project.  as things improve/progress I will ensure to share all with everyone.

PS:  just a note for those legally minded.  any ROMS, 3D models/etc were NOT part of the purchase from the buyers.  only material costs and time were charged.

a lot on my plate == no posts

Yes, I know i’ve neglected my blog for FAR too long again..  well no more.  I’ve made a schedule and I will stick to it.  new posts on many of the projects I’ve been working on to come.  every week there will be at LEAST one.

first coming up in a day or so will be about the FPGA CPU design i’m playing with.  this serves no REAL purpose other than to say look what *I* figured out.  and has already elicited assistance from a fellow blogger.  Alex from http://langster1980.blogspot.ca was a great help in sorting out my Component embedding whoas.

Then there’s the Coleco Video output fix, 2 AVR projects and a Microchip as well as countless 3D printing updates. so stay tuned!

Wheres my Post

Well.  this week went sideways fast.  due to weather issues (5+ CM of solid ice over everything due to freezing rain) my work has been behind.  And of course things snowball.  so now here we are.  the Atari is NOT completed, the post did NOT go out on time and you’re getting another apology from me.  the Atari is STUPIDLY close to complete, the amplifier board has been assembled on prototyping board, the old RF modulator can has been removed, and to add to the cake I changed out the DC power jack because who uses a headphone style power plug anymore?  I will be getting final wiring and assembly done this week and an extra post up to properly cover the entire project.  But while you all patiently wait, I wanted to ask a question of the 3-5 people that actually read these.  are you good with this blog style or should I learn how to actually edit video and start YouTubing my projects?

comments/feedback below, and as always.  Don’t forget your towel!

Atari 2600 recovery

So, this weekend I decided it was time to take my dead Atari 2600 off the shelf.  now it wasn’t scrap ready yet. it booted.. occasionally, but the when and why were magic.  So Saturday evening while my friend played GTA-V on the xboxone and drank bear I sat at my bench and probed away.  power fine… clock, fine…interesting…. things all seem good.  are the chips working…. yup.  oscilloscope shows the clock pins firing in time, good clean power… hrm.  well maybe something from the cart to the chips.  nope all good.  well I went about probing the board for well over 2 hours, and could find NO reason what-so-ever that we were not getting an RF signal.

At this point (around 2am) my friend is done playing and has taken back several beer.  He’s tired and not drunk, but definitely mentally slowed some.  Well he asks, “Did ya check the RF?” “OF COURSE I EXCLAIM”.  I know I did… it was checked when I first pulled this all apart..  well it’s late and he’s had a few.  Time to take him home and pack it in myself.

Next day I’m having coffee with my Uncle Dave as we do every Sunday to keep up on the family/etc and talk Electronics and I mention that I’ve resurrected this project.  He suggests a few things to check so we do..  are we getting video data from the chips….  well well well… it sure LOOKS like we are on the scope, but we have no way to “decode” this analog signal on my computer (likely because I’m not smart enough to do that).  Ok, we can hook the Audio to the scope an Analog Discovery 2 and have the scope output the sound.  Well what we got sounded a WHOLE lot like the Atari 2600 Morse coding a “let me die in peace”.  Well well.. that tells us its doing SOMETHING….  lets find an easy way to feed the signal to the TV.  Turns out there is a super simple circuit that crops the analog signal for composite output which i found here.  and of course I have the parts in my supply.  Oh wait.  I dont have any IC Leg clip connectors… but I have the parts… So Dave shows off his mastery of Soldering and quickly makes a couple Jumper style connects.  we get it all wired up (Figure 1), I’m crossing my fingers, I’m positive Dave is looking around for an extinguisher and we throw the switch.  it’s ugly… its messy…  but wait.. theres SOMETHING on the screen….  and it made an agressive BLIP noise.  (Figure 2).  Ok.  its something… its dirty but its there.. this is good.  Was it a fluke, was it decided to be nice and start this time…. Power cycle.  still there… again, again, again.   at least 5x as I stare in disbelief… OMG It’s working… Well Well Well.  Now I owe my friend a sorry… I’d buy him beer but i bought what he was drinking already so we’re gonna call it square.

ok, now for the meat.


Figure 1

Figure 2

 

Anyways folks, Thats my entry for this week.  Hope to see you next week.

Information & Sources:

Analog Filter (Composite Mod for Atari 2600)
Atari Field Service Manual

Raspberry Pi -> ATmega328p

So, I found this neet litle mini NES case for a Raspberry Pi to 3D print on thingiverse by user DaftMike and decided that I needed to print one.  the print went well and there was no problems getting it assembled.  But even before I opened his website (linked in the thingiverse) I wanted to make my own button control board and have the PI be able to control the LED.  So I started this project..

The 3d printed board in the project is this by user Greystone and has been useful many times.  I always intended to re-work the model to include a place to seat the AVR Dragon, but never got around to it.

Anyways back on topic.  in the image you see the AVR Dragon connected to the Atmega328p (no arduino code here) along with a Power supply via an LM7508.  There is also a tiny little interface PCB I made to connect the AVRDragon to the breadboard and apparently I was to lazy to dig out my ribbon cable so made my own.  on the far side the small red logic level board from Sparkfun which will be connected between the ATmega328p and the Raspberry Pi to protect the GPIO.  More on this project as things come along and there will be a GIT for all code and schematics.

Whats still missing:

  • LED for display
  • Buttons (Power/Reset)
  • Connection to GPIO for Serial Comm and Power
  • Schematics
  • Code

As always I welcome any and all feedback/comments.

 

Where have I been

Well that didnt go so well. Life, Kids, Sports/etc… things get in the way.  but lets fix that now.  I have been playing around with a Mimas V2 for a short while trying to learn FPGA and i’m doing well I think.  Recently I decided to try and learn how to drive the VGA.  although far from a proper working solution I can get the driver to work on my multisync monitor.  I have reached out to a fellow FPGA/Mimas V2 blogger (Alexander Lang) and he’s agreed to help me figure things out.  of course I’m always interested in information/assistance from my readers as well so heres the GIT.

https://github.com/duckyvirus/MIMAS_V2_VGA

Pics, etc will be available soon, unfortunatelly posting this from the office right now.  I also promise to try and get back into the weekly postings again and I’ll share more on my projects (I have several on my bench right now).

as always stay well and don’t forget your towel!

— James

8×8 Dot Matrix Display Complete

TL/DR – see bottom

So I spent several hours trying to figure out why the display acted strange when using the Arduino Libraries.  and Ultimately determined it was the ShiftOut function.  I will be replacing its use with the pure AVR version.  Fully functional and clearly documented.

PIC implementation will be coming at a future date.

I plan to build a simple program (*NIX & win32) to make creating fonts easier.  and for anyone who did not read the previous posts, see below the media.

Please feel free to provide feedback.

(also thank you to robert for the kicad model)

8x8display_code

8×8 led matrix schematic

 

I was in a conversation with my uncle David about a usable font engine for led displays.  And i thought something easily expandable. I took some inspiration from my old C64 ASM days and made a simple enough vertical raster engine.  this is the demonstration code, not the full expandable class which I will post later once I sort out the issues with the Arduino ShiftOut.  I’m positive the code could use a TON of optimisation and improvement which will all occur before I call the final class complete, who am I kidding.  anyone who knows me knows I’ll never be done with it.  there will always be things to improve and ways to make it better.  I wouldnt be shocked at all if this ends up as a pure ASM implementation at some point.