Running at 2.5Mhz is fantastic, but I recon it can go much higher than that. I was surprised when I got my breadboard CPU running at 2Mhz and none of it was on PCBs and the clock was a 555 timer, not even a crystal. You sounded so happy I thought you were going to cry. Well done!

2.5MHz! Wow I didn't expect that, but I guess modern 7400s logic is probably faster than I expect.

Congrats on hitting 2.5 Mips with half the computer still using breadboards.

"Hopefully brings this entire build a bit closer to finishing." I hope not! This should never end!

woohoo. when it's all set into PCB, it may go to 5MHz ! congrats !!

I cheered for you at 1 MIPS. Congrats on such an amazing project.

Wow - this video's not only dropping one bombshell (>2 MIPS) - which by itself is far more than impressive, ... but three! Audio and Video those are - yes, I heard you right, Sir ;-). As you can imagine - I'm totally psyched right now! This means much more to come :) Nevertheless I'm looking forward to the next "smaller" steps, too. With the PCB versions of the Clock- and ALU modules this board will look even more impressive, than it is already. Wish I could press thumbs up more than once.

Awesome! Congrats on this milestone. It was great following this series up to this point.

This is so GREAT to watch! Congratulations James! Seriously, this is one of the few channels I watch that I look forward to seeing a new video in. Thank you!

I remember the great debate (or was it an all out war) between the BBC, Speccy, and 64.... another kiddie and I were "exempt" because he had a QL and I had a Jupiter Ace.... we just didn't count. ;) Great to see your build getting up to microprocessor speed even with the ALU still on breadboard.... that's pretty damn good!

2.5Mhz is a great result for a system with still some breadboards. CPU pipelines are working great...cheers!

Waw that is indeed awesome. Faster than my c64 for sure. Brilliant. Gives me some ideas for something I've been thinking about for a future project

Congratulations. This is quite an achievement. I am amazed that given these of breadboards and the speeds that it is stable.

Congratulations Jim, that was awesome. I was sitting here shaking my head thinking there is no way you will get 2Mhz on breadboards. How wrong I was! It just goes to show there are advantages to building your own CPU rather than using an off the shelf one. I am looking forward to when you get around to creating the video circuitry.

Nice, awesome work! Can't wait to see the PCB build!

Amazing ! Well done James. I didn’t know about the power monitor chip. Thanks for the tip. I’m going to include that in my build. Cheers.

Congratulations! Damn, that's impressive!

Well done James, I got quite excited at the end along with you.

Awesome James!!!! Congratulation!

Really nice work, you've set the bar pretty high!

The first "hands-on" computer I used was a DEC PDP-15. It had a knob on the front panel which varied the clock rate from 1 Hz up to full speed.

Thanks James. Fantastic speed, especially considering the ALU is still on breadboard. Interesting video. Take care.

Nice work!

Congratulations! In terms of peak MIPS, my Magic-1 is just barely holding its own against your machine. Magic-1’s clock runs 4.09 Mhz and register-register instructions take 2 clocks, so its peak MIPS is 2.045 - just barely edging out your 2.025. I’ve no doubt that you’ll blow past it in short order, though. When Magic-1 first came alive, I couldn’t push past 3 Mhz. After analyzing critical paths, the bottleneck was in the way I was forming a physical address via the page table. I redesigned the memory access mechanism to split address translation across 2 clock cycles and that enabled me to get to 4 Mhz. I then went searching for the next critical path to attack, but found multiple (mostly around setting condition codes and branching). So, 4.09 Mhz is Magic-1’s upper limit. Of course, peak MIPS isn’t that useful. Can’t do too much just moving data around registers. It’s memory access that matters. I don’t recall exactly, but a typical memory reference instruction for Magic-1 probably takes 5 or 6 clocks. So, given a typical instruction mix it’s well under a 1 MIPS machine. In the old days, we used the Dhrystone benchmark to measure MIPS. A Vax 11/780 scored 1757 Dhrystones and was considered a 1 MIPS machine. Magic-1 is capable of running Dhrystone, and scores 529. So, on that scale, it’s a 0.30 MIPS computer. Dhrystone is largely an integer and string benchmark. There was also Whetstone for double-precision floating point. Via a software floating point emulation library, Magic-1 can actually run Whetstone. Amusingly, it scores 0.000578 MIPS. In other works, 578 instructions per second - “instructions” not “millions of instructions”. Once you firm up your instruction set architecture send me the details. I’ve done enough retargetings of the C compiler that Magic-1 uses (lcc) that I may be able to quickly cobble together something that could work for you. Then, you might be able to run Dhrystone (and other C programs) yourself.

Congratulations on achieving 2+Mips. My first computer was a ZX81, (1K version), then a CPC464 and then an Amstrad PCW something or other. My first job was in 1990 and it involved using MicroVAXes. In 1996 bought my first PC, between the time I'd seen it in the store and bearing to part with my money, the CPU had gone from 133MHz to 166MHz; thought I had the fastest PC I would every need 😂

You are genius man

I'm late to the party but, Congrats on breaking 1 Mips!

Great video again James, but the VCC symbol not pointing up and the Ground not pointing down makes my brain go Noooooo. Sorry it's just the way I have been programed over the years. :)

About the 555 astable - you can use the output pin through resistor to trigger + threshold with the capacitor to ground to get almost ideal 50% pulse wave with less parts ;-)

damn .... that is fast :D

Congratulations!! Lovely seeing this milestone. I never had any doubt you'd hit 1 Mips. I'm betting you'll do fine up to about 4Mhz, after that it would depend on how fast those EEPROMs you selected are? ( 70ns or 150ns ). Cheers!

30:40 DIAMOND MOMENT

That's awesome! Meanwhile, my breadboard transistor clock is so sensitive to noise that it can't do a few hertz without flickering if I touch anything... :) Side note: the same circuit on a PCB is surprisingly stable.

Absolutely amazing! How much faster will it go when it's all on PCB? Can't wait to find out. It would be fun to take out all but the last value and "Done" UART output for a proper comparison at high speed. :) FWIW I still don't like your block symbols, especially for gates... is that the only option with that tool, or does it have "unit" based symbols like KiCAD?

“Actually Clapping!”

Loving the "Timely Annotations" :) Getting Ninja with YooToob.

This is crazy James, 2.5 Mips with breadboards, awesome. Did you think after this project building the same processor using an FPGA?

I bet it can go quite a bit faster! I got a video generator circuit to run at 8 MHz on breadboards without too many problems

Congratulations! You can probably go onto 4 MHz clock already now. Once you have it all on PCBs you go to 16 MHz. Haha. You should remove that waiting for the UART and just write the results into RAM instead, and just check the results in the end. That way you could get faster execution. Have you thought about making a more compact card-edge connected passive backplane system which fits into a box, similar to the mini-computers of old? Or you want to pin this setup to the wall, right?

I think you can also initialise registers B, C and D to zero by issueing a parallel load to them?

18:40 Opportunity to butcher old "James Sharman" sticker to bottom right of new board missed ;) Branding man BRANDING! hehehe

but how fast can you actually go slowly increase the clock until it stops working

Looks like you need to buy a faster crystal! 😉

Do you have any plans for a PS2 keyboard interface?

Hi James. Do you keep any online documents or schematics of it, even if they are outdated? Thanks?

Zoom zoom!

So what baud rate are you running at?

Looks like you'll have to buy faster crystals!

What happened to the LEDs on the Memory module at 25:44?

The question is how high can it go? I want to know what the absolute limit is.

nstruction and memory address and content displays and switches would be great instead of relying on "EEPROM's" knobs for run/stop, clock speed,single step,deposit,deposit next,examine,examine next next would be great