VIC-20 Build from a breadboard 6502

Why 4:1 multiplexers? Perhaps something to do with allowing video timing for VGA instead of NTSC ? Or perhaps you'll be adding another processor or doing dma for something else ?

This is going to be awesome, I just subscribed, so I won't miss any future parts :)

oooh excited for this

In 80s, in Eastern Europe, there were efforts to copy the successful computers from West Europe. mainly the Z80 based Spectrum. While the original components were not availabe (the Iron curtain emabargo), the ULA chip was reverse engineered, being with a bunch of TTL logic ICs or, as I saw in one specific model, with a combination of TTL chips and a bipolar PROM IC. These Spectrum clones were good, and often more reliable than the original Sinclair Spectrum. For those that wanted the original Spectrum experience, they could use the original ROM from a Spectrum computer, but most Spectrum clones had theirs own Spectrum ROM, sometimes with bugfixes, improvements or localized to the specific country (error messages were in different languages).
I do not , if that was done in 80s, why today the Spectrum fans do not use the same approach, being that the ULA chip is harder to be found and those old schematics are easily available.

Edit. I admired your wire routing technique, where did you get that wire, is there a link that you can provide or a part number for one to search for it? I mean, I found some similar wire, but the plastic insulation is way to feeble, it melt easily or, in one case, the insulation is some silicon that is very hard to cut.

Stop it! Your channel is turning into computer porn Click Bait!🥰 Another awesome video i have 2 x Vic20's with dead VIC's! Cant wait for the Kit!? 😃

I'm definitely looking forward to the rest of this series 😀

What type of wire are you using for the point to point, where you can have the solid strand separate from the kynar sheath? I can't find anything like that when I search for it.

This kind of reminds me of the videos Ben Heck used to make way back. Definitely subscribed.

Just fantastic

Is that 30ga Kynar insulated wire wrap wire? NOT cheap from what I've found, especially if one wants a color assortment. PVC insulated is cheaper, but I wonder how much it melts/shrinks back. I haven't tried it, but have you ever used similar gauge magnet wire with an insulation type removed by soldering? Anyone else is welcome to comment on these questions.

This project could be what the 8-BIT GUY was dreaming of about 5 years ago. No FPGA's and easy to understand and code. Unfortunately its last version is far from that.

great!

This is going to be so good 😊

4:1 muxes because you are going to run 4x CPU clock on the bus? So you get 4 memory access slots, probably 2 for "VIC", 1 for CPU and the bonus one is a mystery for now 😉

This is amazing content... cant wait for the next part. have liked + subed. edit. cant figure out if the multiplexors are for bank switching eprom content, the first pre-emptive multitasking VIC20, or the first quad core VIC20 :)

VIC-20 was the first computer I got as a teenager. Thanks to Capt. Kirk

Ok, now im subscribed. lol
Ive watched quite a few of your videos when they have come up and enjoyed them. If your going to show how to make a VGA card for this, Im in!

It annoys me in the movie Tron the character Sark decrees 'Bring in the Logic Probe!' then proceeds to force the state of the IO port with a Logic Pulser.

I made a display controller for a 128x32 plasma module entirely out of 74xx chips all on a breadboard. Lots and lots of counters. Since I was clocking the display I made it so that whenev the CPU (high speed 8051) needed to access video ram it'd pause the display controller's clock yeilding access to the CPU. Each pixel was 2 bits so four intensities which was implemented by scanning each row multiple times. Took me about a month to get the glitches out, was my first project for these people and really wanted to impress em. To do VIC20 gfx imagine it's gonna a lot more than the 16 or so chips i used :)

I'm so looking forward to this!! Thank you!

Wow, this is bringing back some old memories! A got a big giggle when you described your digital scope as old, given that my own CRO is an ancient analog Tek.

Hey can you do the TV typewriter next? That would be very interesting and useful maybe! Awesome video!

Hell yeah! im so up for this.

This is VERY cool. However should be done with the US Gold standard C64.

What a cool project. Subscribed.

you'd be doing us a huge solid if you showed us how to make an RTX 4090 for your next project....

You want to use an nmos 6502 and 6522 if you want to make it vic 20 compatible.

madness ! Love it :)

Was the Vic20 a small C64 or is the C64 the successer ie Vic20s big brother?

Well that's going to be interesting, looking forward to seeing this and revisiting my childhood with a VIC-20 build.

Thank you for the excellent content you upload.

Immediately hit the subscribe button.

Any chances for gerbers maybe?

More of a 64 man myself but this is a hella cool project!

This is how we were required to do board layouts in my 1991 electronics classes. We were graded on the appearance as much as function because "one day you'll need to troubleshoot it or want to upgrade it."

Is the final product going to be 100% compatible with Vic-20 software, graphics, sound, I/O and all?

Omg, I have never thought about wiring kynar wire like you did here. I.e. solder a blank piece of wire, then cut the kynar mantle to length and push it down the wire to where it's supposed to go. I pride myself for my ability for thinking laterally. But this teaches me again that a capability of lateral thinking is only any good if you actually think of applying it to a problem. ;)

I mean: my solution is to use enameled wire for most of the buses (parallel wires with many connections), and use kynar wire for the rest.

That's a great working solution, and wiring with enameled wire is still faster than your way. But kynar just looks better and is longer lasting (no chance of scratching the enamel and making a short).

But the best thing: kynar has really colorful colors which you can use for the different subsystems/buses, and which really, really help in debugging later on. And also helps a lot when you want to add expansions to the circuit.

Why didn't I think of it? It's so obvious! :D

Fantastic...

Hi DrMatt, it appears that your design employs the faster cycle times and larger capacities of later era SRAMs and ROMS than the devices available at the time. e.g. 70ns or faster vs 450ns of the 2114 & 2716, 32K vs 1K. These capability improvements allow you to greatly reduce part count and wiring. e.g. The memory can be used for 4 different functions within a single CPU/video memory access cycle.

Great video, nicely put together. I look forward to the next video in the series.
Thank you. Vic20-Ian

Hi where did you get the LED strips - Thanks - looking forward to the series

Just as I'm almost finished making my kicad schematic for the SAP6502, the next thing to distract me appears (oh ... look, a squirrel!). My confidence in building the TTL 6502 was a bit shaken in the last 2 videos (status and decimal mode): there are enough chips that there's about a 95% chance I'll get something wrong enough that I won't be able to troubleshoot. (Planning to wirewrap so defects would be easier to find. Plus, wirewrap prototyping boards have reasonable ground & power routing). I better get it done quickly so I can move on to the VIC20.

Yessss. We need more like this.

I'M going for it all in gathering the BITS to build the thing like it

I still have one VC20 from 82? Plus green screen display... Great projects, activates some memories.

Great content, cheers.

My first ever computer was a VIC-20. Hours spent playing Blitz from tape and Radar Rat Race from cartridge. Kids today…pah! ;)

Popcorn time🎉 so interesting stuf

Looking forward to this project. A friend of mine and I have been building our own version from Ben Eaters design.