DIY Video RAM #1 VGA Signals on a Shoestring

This is part 1 of a mini series documenting my learning experience and build of video RAM from scratch by using only a few TTL chips on breadboards. The video RAM is time-shared between a CPU and a circuit that generates a valid VGA signal. Have fun!
Arduino sketches and KiCAD schematics:
github.com/slu...

[@willeyex]

Loving your channel, I can't believe you don't have more subs. I am a big fan of Ben eater but finding you take his work to next level. Keep up the amazing work

[@slu467]

Hi Tom, thanks for your kind words. Glad you found this :-) I too think that it's kind of weird that a video Ben does about the exact same topic (PS2 KB) I did a year ago gets 50k views in 1 day while my stuff gets 500 views in 200 days ;-) If you like my vids, please tell others. It'll help me a lot for future stuff. Cheers!

[@edgeeffect]

I love your "follow my own ideas and keep the designs simple" philosophy... exactly how I work myself.

[@slu467]

Thanks for appreciating :-)

[@pradhumna.ghimire]

Awesome stuffs you got on your channel. Totally hooked and waiting for more.

[@slu467]

Glad you like it! Next part is coming out in a few days :-)

[@cbmeeks]

Looking forward to this series!

[@slu467]

Thank you! I am releasing a video every 2-3 days (4 in total). Stay tuned!

[@thmbr]

Nice project, I've had problem with the oscilator and I fought a little to resolve (because I didn't have the same components). But now it's working, thanks for the video.

[@slu467]

Thanks for the feedback. It is always very valuable for me to hear that you could reproduce all this. Great job!

[@hassanzahin1534]

2:59 those satisfying clicking sounds

[@paulkirchhof9546]

This is exact what we do 41 years ago before low cost chips as 6845 came on the market. The 6845 shows the difference between fix wired video timing and variable timing with control registers. The difficult later is the synchronous Write to the video RAM to avoid output problems if you write very fast to the RAM it comes to disturbed pictures. It is interessant how slu will find a solution. Fine that the next generation can understand what pixel shifting mean.

[@slu467]

Love your in-depth comments and suggestions, Paul. Until I tackle HDMI I will have to sort out a couple of other issues :-) Re-inventing stuff as a one-man show takes time... Cheers!

[@subject2749]

I think this is exactly what I've been looking for

[@shivaramkrishnaaj9496]

Excellent, Thanks a lot, may god bless you.. Keep doing and keep digging the science like this....

[@slu467]

Thanks a lot, glad you like what I do.

[@amnesie6615]

Wieder ein tolles Video, weiter so! Unterhaltsam & dank dir lernen wir auch was dabei :)

[@slu467]

Schön, wenn's gefällt :-) für mich ist das auch "learning by doing". Cheers!

[@AlanMedina314]

Your content is solid. Thank you for sharing Slu4.

[@slu467]

Thanks a lot, Alan.

[@danielhall8818]

Great video, looking forward to the follow on videos.

[@slu467]

Thanks for tuning in again, Daniel ;-)

[@mr.fishfish570]

Awesome!

[@coenraadloubser5768]

[@rjameslower]

i need a book about this!

[@marcelonavarta483]

Muy bueno !

[@giova2927]

Hi I have a fanuc sigma vc600 and this lcd Fanuc LCD A61L-0001-0093 with honda 20 pin cable. I would take this signal on my PC.

[@colonelbarker]

I'm just wondering, you have 16 address lines coming out of the buffers and 14 going into the RAM. The KiCad schematics suggests it is lines A7 on the left buffer and A6 on the right, but it looks like the build version just ignores the upper two bits of the left hand 245. I'm think it may be an error in the schematic, but I could be reading it wrong?

[@slu467]

Hey Aaron, I think you are right, but it actually doesn't change the function at all. The 74HC245 buffers do not "know" their bit number. They just provide 8 "bit channels" each, which you could use in either way, independent of each other.

[@colonelbarker]

@@slu467 true! I was just wiring up the shift registers and buffers here and wanted to get it right. The 8-bit counters I can't for the life of me find in Australia so they are coming express from the US

[@djc1402]

@@colonelbarker I got a bunch of 74HC590s from Rockby electronic components in Victoria last week. They are more expensive than Mouser though.

[@slu467]

It'll be totally okay to use 4x 74HC161 instead of using the 74HC590s. It's just that it takes more space on the breadboards...

[@colonelbarker]

@@djc1402 oh nice! I'll investigate. I've been using RS components a lot recently that offer free shipping and arrive super quick

[@djc1402]

Have you taken what your Arduino Nano VGA code does and translated that into counters and logic chips? The Nano runs at 16MHz too.

[@slu467]

Hi David, that's right. I always thought it would involve too many ICs (for my taste) but it turned out to be quite feasible.

[@djc1402]

@@slu467 It looks like you designed your VGA a lot like mine except I used a ROM for the control signals instead of logic chips and used latches instead of shift registers to input the data. You should try making a colour VGA one day.

[@canaDavid1]

I am a little confused by the diagrams. How do you tell the difference between and and or gates?

[@slu467]

These are standardized symbols for OR and NAND. NAND = AND with output inverted (denoted by the little circle).

[@canaDavid1]

@@slu467 yeah, but I thought and (and NAND) had a straight line at the input end, and not a curved like or and nor. But it might be regional differences of something idk

[@slu467]

@@canaDavid1 Hmm, you are right, David, I am more familiar with the straight line AND, too. I might have picked up a "bad" symbol here... anyway, it's supposed to be a NAND as advertized :-) Cheers and thanks for pointing this out!

[@canaDavid1]

@@slu467 thanks for a kind response!

[@spsmartfast9]

hello May i have the schematic diagram?

[@slu467]

Hi :-) The schematics are in the GitHub repo (link is in the video description).

[@hassanzahin1534]

what oscilloscope do you use?

[@slu467]

Hi Hassan, I am using a PicoScope 2205. The bandwidth is very limited but for quick troubleshooting it's nice to have. Cheers!

[@ducksonplays4190]

this is stupid i did my math wrong so i could run my cpu up to 20 mhz possibly guaranteed 10 maybe 16 probably not but still possible 20 16 mhz is the fastest it would go without the ram being a bottleneck