Ever since I uploaded a few videos of this 8-bit programmable computer, that I built a while ago, I’ve gotten a lot of questions about it. I wanted to answer a few of the most common questions, and definitely by far the most common question, is, “can you show us how to build it?” or “do you have schematics for this?” Or something along those lines. The answer is, believe it or not, I actually don’t have schematics for this thing, I never sat down and drew out a full schematic. Because of how modular everything is, or how modular this architecture is, I was able to build each piece of it by itself, and build it, and test it, and experiment with one module at a time, before I had to put it all together. It wasn’t really until all the pieces came together that I really had to be a little bit more thoughtful about how it was all going to work. For that I had this really good model to follow in this book that I really recommend, “Digital Computer Electronics”, by Albert Paul Malvino. Unfortunately, I think the book is out of print, but hopefully you can find a used copy online or something. This book has an architecture… has a couple architectures. One is the SAP-1, which is, “simple as possible”. The goal is to be a very simple computer architecture, that demonstrates all the crucial ideas behind computer operation without being any more complicated than it needs to be. The architecture that they have in here, is basically the model that I followed, what I based this computer on. So you can see that all of the same components are there. There’s a program counter here, there’s the memory address register, the 16 bytes of memory that are used, programmable read only memory, I’ve got RAM but, same difference, as far as the operation is concerned. An instruction register, the control unit, which is all this stuff down here, and you can see that they have all these signals going out, that come back in to all the other components, and that’s what all these yellow wires are. They’re all the control signals. They come from the control unit and go out to all the different pieces to orchestrate everything. The accumulator, which is the A register here. The ALU, which is the arithmetic logic unit, which in this computer, just adds and subtracts. Those are the only arithmetic operations it knows how to do. And then the B register. The A and the B register are the inputs for the arithmetic. And the output register, they have a binary display, I’ve got a decimal display which I thought was a little nicer. That’s one enhancement that I made. I made a few other enhancements to this as well, primarily around the instruction set and what you can actually do with it. The model here in the book, it talks about the instructions having a “load A” instruction, an add instruction, subtract, output, and halt, and that’s it. I added a couple other things. I added a load immediate, which just lets you save a little bit of memory, if you wanted to load a particular value into the A register. And then a “store A” command, which in addition to the “load A,” which loads the accumulator from memory, you can store what’s in the accumulator to memory. So that let’s you build a little bit more complex programs. I also added jump instructions, which I thought were pretty important for a programmable computer. There’s a regular jump instruction, there’s also a conditional jump instruction, that jumps when the carry bit is set, anytime the addition over flows. So you might still be wondering, can I just tell you how to build this thing already, can you draw up a schematic or something like that? Well, I’ve got some good news. That is exactly what I plan to do, to make a bunch of videos, that go through every step of the process. I am planning to actually build a whole new copy of this computer from scratch, and have videos of all of it. The bad news is that it’s going to take a while. I don’t have a ton of free time, unfortunately, but my personal goal is to make one video a week, at a minimum. So we’ll see how well that goes, but even with that, I want to make sure I’m covering everything from first principles, not leaving any mystery about why things work the way that they do. I don’t wanna ask you to take anything on faith, but going step by step, probably means it’s going to take a while to get to everything. So at least… at least a few months. Probably longer. I hope that it will be worth the wait. My goal, and I’m convinced that anyone can build this computer. As long as you’re patient enough to wire it all up, carefully, and you have the persistence to troubleshoot the inevitable wrong connections, or broken connections or something. I’m convinced that anyone can build this and really understand at a very deep level, how a computer works, by building this. Even if you, don’t have any experience with this sort of thing, or with electronics. In fact I really hope, I’m really looking forward to that happening, and people building these things, and improving on it even. So, I think for the next videos, I’m going to be traveling over the next week, so it may be in a couple weeks before I can get the next video up. My goal is to just start focusing on the clock, as the first steps, and walk through building this, the clock circuit, from scratch. There’s a couple interesting things going on here. The clock, of course, coordinates everything in the computer, the timing of everything. In this case, you can adjust the speed of the clock, you can see here I’m slowing it down, so everything else is running slower. You can also stop the clock, and then step one step at a time, which is very useful for troubleshooting something, if something isn’t working, which inevitably, if you build this you’re going to run into a point where something isn’t working, and you need to go step by step. A couple features that are of the clock, is that it uses the 5-5-5 timers, so I will go through how those work, and they’re being used in a couple different applications, in the clock circuit. So, I think that that’s the next thing that I’ll do, the next set of videos. You can look forward to seeing those. I hope you’re as excited as I am about this. Again, I ask for your patience, it’s going to take a while to get through it all, but I hope it will be worth it. If this is exciting to you, please give this video a thumbs up, and subscribe to the channel, tell all your friends, cause if you like what you see, knowing that people find these videos valuable, is really motivating to me, so subscribing and watching the videos, is honestly the best way to make sure that I keep working on them. Thanks for watching.

8-bit computer update
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100 thoughts on “8-bit computer update

  • February 28, 2019 at 10:03 pm
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    If you want to follow along with this series and build your own, I'm now selling complete kits! Check out https://eater.net/8bit/kits.

    Reply
  • July 6, 2019 at 7:23 pm
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    Your channel is gold, thank you for sharing

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  • July 6, 2019 at 7:36 pm
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    most valuable 2019 🙂

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  • July 6, 2019 at 8:38 pm
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    I now understand why star trek computers have flashing lights.

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  • July 7, 2019 at 3:53 am
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    I watched every.single.video. That was one of the most outstanding and interesting project I have ever seen and I have close to 0 experience with the subject matter yet I thoroughly enjoyed it all. Thanks for that amazing project!

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  • July 7, 2019 at 4:55 am
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    Instead of drawing up a full schematic, it might be easier (and faster) to write out the design in VHDL or Verilog and post that somewhere on github for people to get. That would also promote the adoption of hardware description languages and configurable logic (i.e. CPLDs and FPGAs) among hobbyists, something that has been very slow to gain traction, despite efforts from various sides.
    Further, if you ever want to have a look at more contemporary CPU designs (which in their basic implementations aren't any more complicated than the older bus design you implemented), have a look at "Computer Organization and Design" by Hennessy and Patterson. And lastly, I have to say I love your channel, you're one of the best educators and explainers in Electrical Engineering on Youtube. Big Thumbs up!

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  • July 7, 2019 at 5:44 am
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    This looks like a wonderful project. Wondering, would this work on something like a virtual breadboard circuit designer like the one at tinkercad.com ? (not sure if there are components here which would be missing, or other considerations).

    The other thing is… I haven't attempted an electronics project since high school (a while ago now). I'm looking at beginner electronics resources to get back into things. Is this jumping in the deep end?

    Thankyou for this educational series. Again, looks very interesting and informative.
    Cheers

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  • July 7, 2019 at 11:01 am
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    best youtuber ever

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  • July 7, 2019 at 11:13 am
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    can it run crysis

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  • July 7, 2019 at 1:03 pm
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    this shit would look sick on a pc front or side panel

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  • July 7, 2019 at 6:03 pm
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    Look up The Bugbook by Peter R Rony. There are pdfs online.

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  • July 7, 2019 at 7:30 pm
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    Does Crysis run on it?

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  • July 7, 2019 at 7:33 pm
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    Amazing video! Just started watching your content, and even though I don't deal with electronics, it's really informative and interesting 🙂

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  • July 7, 2019 at 10:16 pm
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    2 questions Ben:
    there is a lever on Einstein's calculator that pushes the calc operation…
    how does your system update & where on the board is that?

    most people do not know about steam powered computing.

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  • July 8, 2019 at 2:16 am
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    The fabled god of r/electronics

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  • July 8, 2019 at 3:28 pm
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    The factory must grow.. damn, wrong video.

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  • July 8, 2019 at 3:53 pm
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    Can this possibly be upgraded to a mips computer so that you can run real programs? Is it possible to connect dram sticks with some kind of comyroller?

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  • July 8, 2019 at 4:43 pm
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    You are the best, please keep posting videos

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  • July 8, 2019 at 8:22 pm
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    All you need is a conditional branch. Oh wait, you already did that.

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  • July 9, 2019 at 12:28 am
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    Anyone can build this. All it takes is time. I wish more people would take this on. You are a cs God rn. Much love!

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  • July 9, 2019 at 6:12 am
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    A Computers needs a program to run but a program is written on a computer(so what came first the chicken or the egg) oh and thats a work of art👍

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  • July 9, 2019 at 6:56 am
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    But can it play Doom?

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  • July 9, 2019 at 9:55 am
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    Can I get pdf for this book

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  • July 9, 2019 at 5:50 pm
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    Could it run doom?

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  • July 10, 2019 at 8:55 pm
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    This is incredible, because always in schools you only see this part in a theoretical way, and you do not finish understanding how a computer actually works. I hope your channel is very successful because so much work deserves that recognition. Congratulations!

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  • July 11, 2019 at 6:53 pm
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    so how's the cable management, Ben: yes

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  • July 11, 2019 at 9:40 pm
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    Very cool! I'm following along your very simple videos, and I hope to learn a lot from you.

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  • July 11, 2019 at 11:26 pm
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    the great question is…
    it runs crysis?

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  • July 12, 2019 at 5:44 am
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    Does the system have a name? I feel bad just calling it the 8bit bread board computer.

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  • July 12, 2019 at 9:15 am
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    https://mikemestnik.net/simulide/ I've started a SimulIDE project to emulate this computer and I've started patching SimulIDE to support this machine. https://gitlab.com/cheako/simulide/commit/c001358c085d902b7452d725a8056f0e32b06cd0

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  • July 13, 2019 at 4:05 am
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    Can it Run Crysis

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  • July 13, 2019 at 3:21 pm
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    Great, seems like you explain exactly what I always wanted to know. What happens at the machine! I only knew higher programming languages and ever wanted to understand, exactly that what you explain here. Thank you so much -> ok than I will leave another Comment on the Last Video then !! : – )))

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  • July 13, 2019 at 4:18 pm
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    I can smell that book

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  • July 13, 2019 at 10:23 pm
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    OMG you know so much profesional stuff, you can even program and use Photoshop, what is your IQ and profesion? Are you working for NASA? 😀

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  • July 13, 2019 at 10:44 pm
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    drinking game!
    every time he says "you know" take a shot

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  • July 14, 2019 at 1:48 am
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    I’m having difficulty figuring out the order of the 8-bit Breadboard Computer series. Which video is the first, is there somewhere I can find an index?

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  • July 14, 2019 at 8:00 am
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    I found the third edition of digital computer electronics on the net, does it have the same information?

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  • July 14, 2019 at 8:54 am
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    Can it run crysis ?

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  • July 14, 2019 at 4:09 pm
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    Im a software developer and I recently found your channel and I love the content even with my almost null experience on logic circuits and eletronic, thanks and keep it up.

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  • July 14, 2019 at 4:45 pm
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    Fat fucking sub from me

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  • July 14, 2019 at 11:33 pm
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    Another tour de force expose of the principles of the ubiquitous computer that has automated and added intelligence to basic machinery in every aspect of daily living. Coincidentally at about the same time "curiousmarc" and a group of digital enthusiasts have successfully restored to full working state an Apollo Guidance Computer! Yes and to see the state of digital technology in the early 60's as developed by an MIT professor for both permanent and erasable programmable memory based on ferrite cores (rings) and the minimum number of wires to address each core or "bit value", this is a must see! Also a German documentary on the CPU model and instruction set used by the Apollo AGC may be a little dry but with Ben's explanation of microcode and instruction set as an arbitrary decision makes it possible to understand this whole historic garbled story of half facts and cold war jargon for the first time with real evidence and calm explanations. Well done Ben! Thank you for showing how its done, by good example and good will.

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  • July 15, 2019 at 12:20 am
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    Let's overthrow Intel, AMD, NVIDIA, and the rest of them!!!!

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  • July 15, 2019 at 11:10 am
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    cool

    Reply
  • July 15, 2019 at 11:38 am
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    HEYYY, could you build a PCB for this? ONE GIANT PCB. You could sell it!!

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  • July 15, 2019 at 5:35 pm
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    So can you install a linux on it?

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  • July 16, 2019 at 4:31 pm
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    Could you plz make video on CAN and USB protocols

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  • July 16, 2019 at 11:15 pm
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    if anyone is in the Boston area and finds this completely fascinating, the second semester of Physics 123 at Harvard university is basically building one of these. I recommend it extremely highly, it is incredibly fun.

    anyone of any age is lowed to sign up for the class at the Harvard Extension School, no entrance exam or anything.

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  • July 17, 2019 at 3:13 pm
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    Can anyone tell me the name of the book?

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  • July 18, 2019 at 4:39 pm
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    Thanks for book recommendation. Thanks from Texas.

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  • July 19, 2019 at 8:26 am
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    OMG Ben!!!! Where were you when I was in college? The way you explain stuff is super easy to understand…. I don't know what you're better at: computer engineering, or teaching! I have watched this playlist over and over, and every time I get more empowered and inspired! Seriously Ben, keep this sh*t up man! Btw… you should consider doing another video series creating a 32 bit computer on a simulation application like Logisim. I am currently using it to build/simulate your 8 bit computer. I would then like to move onto building/designing a 32 bit MIPS based architecture once I learned a bit more about it. That would be such a cool video series to watch and learn from, please consider doing it. Thank you so much for your time and effort making these videos!

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  • July 19, 2019 at 1:19 pm
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    can it play crysis? :V

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  • July 19, 2019 at 4:05 pm
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    yes! I finally found a new hobby. I'm gonna do this

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  • July 19, 2019 at 7:27 pm
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    but can it run crisis?

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  • July 20, 2019 at 9:30 am
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    you're fantastic at explaining this stuff. I'm taking a logic design course right now and this makes it all fall into place! Very inspiring projects, I'll probably try one or two of your projects sometime soon.

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  • July 20, 2019 at 7:37 pm
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    wow a computer that bad has rgb

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  • July 21, 2019 at 4:23 pm
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    falls jemand das buch braucht https://www.ebay-kleinanzeigen.de/s-anzeige/-80-digital-computer-electronics-albert-paul-malvino/1166597067-242-6446

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  • July 24, 2019 at 8:42 pm
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    I’ve been a computer engineer since 1970. This is Absolutely Fabulous. Thanks from Orlando Florida

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  • July 27, 2019 at 9:22 pm
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    I just went through the 44 videos on this playlist. 👍🏽👍🏽. What memories. Very interesting and well presented. Back in the ‘60s in got a Radio Shack electronics lab. In the early 70’s I was a bench tech repairing TTL boards, working for digital equipment corporation. I’m still a computer field service engineer. Thanks from Orlando Florida.

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  • July 29, 2019 at 9:03 pm
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    You have the best blinkenlights, fine sir!

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  • August 2, 2019 at 4:03 pm
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    Sir, can we drive an LED with a current source ?

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  • August 3, 2019 at 9:45 am
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    Can you overclock it?

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  • August 5, 2019 at 2:10 pm
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    Great job! Now I can understand how logic part of processor works. Probably I'll try to build my own computer.
    Thanks

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  • August 9, 2019 at 8:02 pm
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    What if someone made a big ol' PCB for this?

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  • August 11, 2019 at 5:06 am
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    The Master…

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  • August 11, 2019 at 5:08 am
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    Variable clock speed, fun R&D… just Wow…!

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  • August 11, 2019 at 7:53 am
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    but does it run crysis?

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  • August 12, 2019 at 1:10 pm
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    what is the book in video?

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  • August 13, 2019 at 7:15 pm
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    But Tony Starks never has his flash light blinking

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  • August 14, 2019 at 4:16 pm
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    So can it run minecraft ?

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  • August 14, 2019 at 9:53 pm
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    For those who are intrested in 8-bit computing, take a look at my channel, im working on a full documentation on my latest 8-bit computer

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  • August 16, 2019 at 7:20 am
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    you should add a VGA out put to connect to a monitor and maybe even add the video card you made to the 8 bit computer plz o this like so he can see

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  • August 16, 2019 at 7:26 pm
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    It looks like the Cream Soda Computer by Steve Wozniak.

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  • August 17, 2019 at 1:28 pm
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    Its beautifull for eyes ….

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  • August 20, 2019 at 3:06 am
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    Past Ben, I've seen the future, it is worth the wait, and you do a beautiful job of it. Thank you. And yes, you next 44 videos are incredibly informative.

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  • August 20, 2019 at 12:59 pm
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    If somebody wants the book he's talking about: https://newyork.craigslist.org/brk/bks/d/brooklyn-digital-computer-electronics/6960562693.html

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  • August 25, 2019 at 7:18 pm
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    FWIW, the third edition of the Malvino book is on archive.org in PDF and other formats.

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  • August 26, 2019 at 2:13 am
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    Ben, have you watched any of Jerry Walker's videos? He has done something similar with an 8-bit discrete transistor computer based on a simplified Z-80 CPU architecture and he's written a book about it (Computer Time Travel – How to Build a Microprocessor from Transistors).

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  • September 4, 2019 at 10:31 am
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    Now you legit can ask can it run Mario?

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  • September 11, 2019 at 5:12 pm
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    best

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  • September 14, 2019 at 7:37 am
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    I watched all of the videos about this 8bit computer you did a very good job there I really liked the way that you explained every thing down to the resistor And I have a suggestion what about another more powerful computer that can do a lot more things like video and sound and such you dont have to bulid and think about every single pice on your own the community can help So what do you think?

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  • September 15, 2019 at 5:15 pm
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    Where did you bought the book?

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  • September 15, 2019 at 6:24 pm
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    if someone wants the book he is talking about https://newyork.craigslist.org/brk/bks/d/brooklyn-digital-computer-electronics/6979268614.html?lang=en&cc=gb

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  • September 17, 2019 at 9:42 am
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    Paul Albert Malvino is best author, I have studied basic digital electronics from Digital Electronics book authored by him.He gives to point crystal clear basic concept of digital electronics

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  • September 17, 2019 at 2:47 pm
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    Now install Windows 10

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  • September 18, 2019 at 4:23 am
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    do ya have a parts kit that is all ready ?

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  • September 20, 2019 at 2:27 pm
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    U r amazing
    😀😀😀😀😀😀😀😀😀

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  • September 21, 2019 at 4:22 pm
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    This is amazing

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  • September 22, 2019 at 1:07 pm
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    can I SAY I LOVE YOU.

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  • September 22, 2019 at 4:04 pm
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    When a random guy on YouTube makes a better operating system than Windows….

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  • September 24, 2019 at 2:48 am
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    The one question that has been on my mind about this is: How much electricity does this use under load?

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  • September 26, 2019 at 6:36 am
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    Finding that book you use was a bit of a challenge. I was able to find a copy I can barrow in my local library's link+ network. I don't know when it will arrive for check out, but I am looking forward to reading it.

    Reply
  • September 28, 2019 at 7:19 am
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    i really hope you can post a video on using a 74ls00 and LM324 DIY a Signal generator。

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  • September 29, 2019 at 9:21 am
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    Hi Ben, Is it possible to program a microkernel inside this computer?

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  • September 30, 2019 at 6:28 pm
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    Can you hook it to a monitor? You also build a video card….you know….Go all the way. From the logic gates all the way to showing simple instructions on monitor. Now that would be really something. Keep it up Ben! I am a die-hard fan already!

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  • October 2, 2019 at 5:28 pm
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    6:19 I forgot you stopped the clock, and thought my computer was buffering.

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  • October 3, 2019 at 6:05 pm
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    I think my first improvement would be a raspberry pi using GPIO as the keyboard. Dip switches seems slow to me. 🙂 Maybe I'm lazy.

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  • October 7, 2019 at 4:39 am
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    Why is that calculator so big?

    Reply

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