Category Archives: Uncategorized

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.

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!