Lightpens Explained Using Slow-mo + A Rare One Saved
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- čas přidán 8. 09. 2018
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🍟 ON TODAY'S MENU: Let's take a more detailed look at how light pens work, using the magic of a 20,000 fps high-speed camera shooting the CRT, and then set about repairing a rare retro one from an Amstrad PCW 8256/8512, with some help from the puppy. Do you think my diagnosis was correct? Let me know what you think in the comments!
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THANKS & NOTES
🕹️ Thanks Super Cartoonist for the slow-mo camera/footage: / superpowersquirrel
🕹️ Thanks to Sean Harrington for some light pen technical info
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Thanks for watching! Is this how you thought light pens worked? And do you think my diagnosis about the "trigger" was correct? Comment below & cheerio!
Hi buddy! Again, the best production quality, delivery AND material!
I really appreciate that. I put a lot of work into these. Thank you for noticing! 👍🕹️
Love love LOVE the super-cute puppy! She did most of the work explaining to me how electronics diagnostics / repair should go. Does she help with schematic CAD work, laying out traces? A dog tells all about their human companion. Your dergies seem to always include you in their video productions. :) lotsa love going around there. Most such benches feature a cat biting wires in half, laying on the keyboard, blocking your view of the monitor, deadpanning you...(A certain orange Tabby named Higgins comes to mind).
I'm training her on CAD and gerber files now! Unfortunately she thought I said gerbil and got a bit excited. 🤦♂️
Mitchy co-designed the Amiga, so no reason why your puppy can't do CAD.
I vaguely remember that on C64 was a very simple project to build your own lightpen at home back in the day. Few cheap components were needed, the photo-diode of course and little more. The magic was in the software because the VIC chip already knows where the raster is at a given moment.
I used to work for an electronics assembly factory. The solder paste printers had a light pen based user interface, which was a bit fiddly to use. Our boss wanted to save some space so thought it would be a great idea to change the CRT monitors for nice new LCD screens. He never managed to live that down!
😂🤦♂️
But since your boss replaced that crt monitor in favor for an lcd screen, the light prn became useless.
Ahahaha what a nubins
Oof--obviously your boss didn't do his homework regarding light pens...... :)
Ok, can we all just agree that........ PUPPY!!!!!
Yeah,, but it was distracting for me.
Very cool. I haven't seen a light pen in action for decades, and I never really understood how they worked. I have learned something new today. Thanks Professor Peri!
You're welcome my young Padawan! 😉🕹️
Very much looking forward to the first repair video of "puppy peed on my keyboard" - lol, great stuff as always. Many thanks for creating and sharing, Bruce.
I think it's coming...
And thanks!
Awwww. How cute is Puppyfractic here? Nearly cuteness overload!! Good work with the fix, too!
Magical? I am currently having that feeling of absolute awe over doing illustrations with my apple pencil. Amazing stuff! This must be the 80`s version of that feeling.
You could make beautiful surreal memes with that might pen
I know this is an extremely old video, but I really did like this machine, though the ones we had at work were the 9512. Not sure what the differences were (apart from the disk drive,) but a very nostalgic video for me. The screen on it was amazing for the time even though it was only green.
I have been eyeing up the PCW in the background in your videos for some time... it's lovely to see the PCW get the limelight at last. I used to be a one-man-band software house for the PCW (with a few ports for the CPC) and kept on using mine as my day-to-day computer all the way up to 2002. It's still in the cupboard. I think I'll boot it up again for some nostalgia. Thanks, love the videos, and greetings from London!
I love that machine. Have you seen my light pen repair video on it?
While I lived in Canada my girlfriend and I were walking to visit her cousin and it was large item night (when you could throw anything out for the bin men to pick up). I spotted a PCW 8512 with printer and grabbed it. It was fully working and came with the CP/M disk. Lucky find. Shame I was unable to bring it back to the UK with me.
I was lucky to find one at all in the USA. Very rare here.
Even back in the day I could never find a use for a light pen besides "tech demo". I had one for my C64, and poked it on the screen a few times before putting in a drawer forever. I wonder if I still have it somewhere...
I am so happy right now that I found your channel. I love your voice and the way you explain things. Thank you for being on youtube!
Thank you for your kind words! Means a lot 👍🕹️
Very cool episode, Perifractic! A masterpiece! I came across it, because i uploaded myself a lightpen-episode for the commodore plus/4 today and was curious to learn how they really work. Thank for clarifying :) Enjoyed every second of it.
Best moment ! New video.! My Sunday is complete
Surprisingly educational and fun! I’d love to see more videos like this!
oh boy have we come far with digital pens. now we have preassure sensitivity (getting thicker lines depending on the preassure you apply), tilt sensitivity (so you can shade like with a pencil) and ofcourse no cable to attach anywhere.
Not only am I addicted to your songs I adore your videos!! Great stuff!! Even if the CRT whine brought be back to the 90s :D
Thank you so much! That means a lot to me. 👍🕹️
A smooth insertion is never a joke ;-)
🍆
getting the puppy in the video is a very low move, i can't stop looking and how cute is.
This has to be the comfiest channel on youtube
Thumbs up for the puppy ;) and great video editing and content.
Super desoldering skills, nice to see some effort with the right tools used and an IC socket inserted for future ease of removal. Great channel, though I was surprised to see that the Sega iDog was as advanced and life like as I remember.
Haha and thank you!
Great video. Beautiful pup!
Wow, Puppyfractic! He looks so little compared to now!
Superb video! Very educational and as usual with juicy content ! :D
Cheers mate! Glad you liked it!
I've implemented a super accurate light gun on my Z80 FPGA project (crummy quality video is on my channel) it works by using the fact that the lens is circular and that it triggers over multiple scan lines, it finds lowest X per frame to find the centre of the gun where its most accurate.
Neat!
Interesting. Sounds like a lot of extra work, but at the same time, the extra accuracy never hurts...
I've been trying to figure out how to 'fake' the logic of a light pen personally. Because they only work with a CRT, when you have an older system on a modern display, nothing happens. So I was trying to figure out how to fake the output of a light pen in such a way that you could use some other sensing system and then convert the values.
I came up with something that'd work in theory, but I can't think of a way to synchronise this unrelated positioning system with the start of a frame - which is necessary to get any degree of accuracy out of it.
Haven't come up with any automated method so far.
A calibration step solves it if you have control over the software involved, but the point of it was to replace devices in existing hardware, where that typically isn't an option...
Ah well.
Very cool !! Loved it , as always
Thank you so much!
Hunky guy holding an adorable puppy talking about retro-tech... I don't think this could be any better ;-)
😊
As always - phenomenal! thx for your efforts
Thank you! You're welcome 👍🕹️
Great Repair! love the artwork you did :D
Thanks! It's for sale...
1:26 actual screen photographs, if you can believe it 😂
I know right! I never thought about it before but I guess they had no way to capture screenshots at that time
I love your puns. I laugh and laugh because You are a Funny guy. :D
One thing I've always thought about with light pens on crts, regardless if it was on the Fairlight CMI, C64, or any other piece of hardware that used it... was the assembly code written to actually get it to work properly. Boy, oh boy, I can't imagine the amount of debugging.
Don't you dare pardon your glorious puns!
Very interesting! Thank you! :)
I wish my Joyce still worked. It was a lovely machine.
They're very special 👍🕹️
Happy Trees! Happy Puppies!
Great Fun and a Great Lesson! Cheers!
Thank you! You're welcome 👍🕹️
excellent vid from start to finish. Its very easy, for some of us, to see the amount of effort, planning and production you pt into these great vids and we appreciate it very much.
as for someone down voting a lightpen fix? how dare you! hahaha but really it was great how could anyone not like this?
Keep it up my friend! loved that apple II pie 9 bit reference, hahaha
Amazing video as usual, Perifractic puppy agrees
Great to see that you got it working using the new pen interface. Even though you've now explained how the pen works it's still seems like magic. Very clever stuff for the time.
It still seems ahead of its time. Processing and updating the screen in microseconds. 😲
Now look what you've done! I've gone and bought a lightpen for my C64 :-) I had one back in the early 80s, so even though I didn't use it much it's fun to get one now even if it's just for nostalgic reasons.
Enjoy!
That's a nice monitor
Checking for leaking capacitors was a breeze as there seemed to be no electrolytic caps there. 😊
And none were leaking!
I think I know how the lightpens work but let's see if I really do. I didn't know entirely, thanks for teaching me the rest of how they work!
*gasps* This was before my beloved EE-OOs by Lady Fractic?! Oooooo. I like traveling back in time randomly like this. Thanks to the YT suggestions algorithm.
Glad you enjoyed it!
My Grandad had a PCW256 and mainly used it for locoscript. I remember the keyboard keys that made a funny springy noise! So it had a Z80? we always believed it only had an 8080!
LocoScript FTW!
Another great video! This one takes me back to fond memories of the light pen I had for my Commodore 64. Nice nod to Mr Bob Ross.
This video really has it all
Thank you so much! That means a lot to me. 👍🕹️
So nice
Another great vid Christian! I remember playing a flight simulator for the PCW8256 think it was called Harrier. Love your commentary as always, makes it easy for a thicko like me to understand.
Thank you! Haha. I'll check out Harrier on eBay!
Oh yes, that’s strike force harrier. I never worked out how to lift off.
Ah, light pens. Such a quirky technology.
Sometimes you see the same tech in really weird form factors though.
For instance, the SNES Super Scope, in spite of appearances is a light pen, and has a lot of the same implications of one...
I rarely comment, but your videos are cool; love the puns too. F>art made me laugh.
I think the puppy was functioning perfectly every time!
Nice explanation, easy to understand and a computer not seen round these parts (USA) back in the day. Oh and puppies. Who doesn't like that? 👍👍
I'm glad it made sense! It still seems like black magic to me when I actually use the thing. Things. I have 2 now! Cheers Xer Race!
That music sounds like it comes straight outta "how it's made"
I'll take that as a compliment! perifractic.com/music 😉🕹️
@@RetroRecipes It is, really. I love music like that! It's like it's own genre, "How It's Made" music XD
Thanks! Was there a particular song / time where you liked it. I can use it again on the next video.
@@RetroRecipes The intro song in this one reminded me of How It's Made the most
3 inch? What is this travisty?
Whats a billysecond? Wait a second i ask billy...
you have a real bob ross kind of voice already. it's hard to make art with so few pixels, you do alright :) cute puppy, and fun video.
8:20
The "i" thing in top left says "9-Bit Guy". Intended or...?
I added 1 bit for parity
Oh, so you assume he's corrupt?!!?
Lol
You can very nicely clean pins of an IC, by using your de-soldering station - they will look like from factory.
Very interesting! And best regards to your little hairy trainee! :-) Your Doktor64.
I really want to pet that dog. :-)
Thumbs up just for Astrowars.
Hooray, new video.
Also one question: I want to know what software do you run on the TV screen, is it some kinf of Linux Desktop manager?
If you mean the intro, that's actually a Chromecast showing my logo. 😊
@@RetroRecipes Ah, thanks for your input.
I designed pub layouts back in the 1980s starting out with a program called Racal Redac. It ran on a DEC PDP-11 and used a light pen similar to this one. Instead of a white screen, the light pen worked on a black screen. From some serious time on this system I can tell you a light pen is a terrible user interface. After eight hours of using the pen, your elbow, wrist and fingers felt like they were on fire from holding the pen constantly against the CRT screen. We called it the “Redac Elbow”. Just a little history.
Would be great if light pens worked on LCD screens :-(
There was actually such a thing but it didn't go far
wow. had to laugh we bought my cpc464 from billy guyatts discount city here in australia! only thing i'd have done different is checked voltages and with a logic analyser each board /chip pin from the non working to working before going down the chip swap route, but, the process of elimination worked just fine. thanks mate. yam alpha.
Thanks Yam! ;) I wanted to use my logic probe by comparison, but I would have had to open up the monitor housing to get the 5V line, and somehow have both light pens connected at the same time... there are ways to do all that and workarounds, but chip swapping felt right :D
.....could always probe the good one (with logic probe i mean ;)) and then put in the bad one and compare. but yeah i hear you. sometimes chip swapping is easier - esp when you have the right tool (solder sucker) for the job it gets so much easier!!!!
I'm sure I've got one of those somewhere, that I've never used.
I had no idea you could get a light pen for the pcw. Im going to have to track one down.
How come your pcw requires that adaptor for the edge connector on the back? Mine just slots straight in.
I'll be putting the second one on eBay soon! In some countries there was additional shielding to meet regulations so a different connector was used
ahhh I see. Mine is the standard British version so that would explain it.
Wouldn't have been quicker, easier an cheaper to source the replacement ICs rather than another light pen?
At the time I didn't know they were still made, or that the chips we're definitely the fault. Could've been elsewhere. New ones are $5 for a set of 5 on eBay, so multiply that by 7. Seemed wasteful. By luck the 25 pence one was found used but tested as working. And now I have 2 working light pens! 👍🕹️
Seriously made me cringe that you used a working one to troubleshoot the bad one. Worked out in the end!
@@RetroRecipes most of it appears to be 74 series logic chips though - those have been in continual production in various forms since the early 70's and are still in production. They're basically commodity parts and within reason 20 different manufacturers all offer interchangeable parts. (there are some variations in terms of operating speeds and voltages, but still.)
Pretty much anybody with even basic electronics knowledge should be able to recognise a 74 series logic chip when they see it.
And if you go to say element 14 or mouser or the like you'll probably find most of these for 10-20 cents each. (if not less.)
Keeping an eye on what the major electronics websites stock, and looking up datasheets in an important skill here. As is being able to figure out if there are modern equivalents of the parts involved.
For instance, z80, 6502 and 65816 processors are still made in new form and are thus easily available. (with potentially higher clock speeds), and may be usable to fix older designs if you're careful.
(nobody makes motorola 68k processors anymore though.)
Similarly, SRAM, 74 series logic chips, and a whole array of digital logic, bus transceiver and other assorted off the shelf components frequently seen in older designs is not at all difficult to find modern replacements for.
Ebay CAN be cheap sometimes, but generally I wouldn't use it as my first source for stuff like this;
Ebay is better for finding more obscure or older parts that definitely aren't available new/have new equivalents anymore.
(For instance, right now you'll have a hell of a time finding loose SCART connectors suitable for custom projects.)
I guess I don't have basic electronics knowledge then ¯\_(ツ)_/¯ I checked Mouser and they didn't do them. Let me know if you find them available new anywhere in that exact configuration as I couldn't.
You got a cute dog.
Loved my Flexidraw on my C64 and 1902. Not sure how i scraped up $80 back in high school for a light pen though (still have the receipt). lol
Including shipping from Poland? Nice! 😉
I understand the need to add sfx sounds, but things like paper and soft cloth making glass souns? Do you have tall pieces of glass, standing like dominoes all over your room, just to throw stuff at them?
Also, which method did you use when printing on banana?
How did you know, have you been in my studio?! The banana came that way; see recent unboxing video 👍🕹️
Neat video as usual Peri.
I like your new co-host. She's cute. 😉
the slow mo guys actually made a video showing the individual pixels being drawn, so that might be a nice place to see it up close
Thanks. I had watched that but it didn't seem to show individual pixels being drawn on CRT. Even the fastest cameras can't yet seem to do that.
@@RetroRecipes they did scale down the resolution to make it possible
Interesting. What's the timestamp where it shows that on a CRT?
czcams.com/video/3BJU2drrtCM/video.htmlm51s here is the time where they go as slow as possible and you can see the individual pixels, then they go into how fast mario's moustache is drawn
Ah yes thanks. It's more like chunks of 30 pixels. I'd love to one day see each pixel appear one by one! 👍🕹️
Can you make replika slim version and little modern touch ?
awww...puppyfractic so small =)
Nice presentation, I actually knew how they worked (and had a laught at one of the other respondednts boss trying to make it work on an LCD screen) but I kept watching as it was a good presentaton. Pity you high speed camera could not capture the actuall dot scanning across the screen.
I don't think any exist that can capture each individual pixel 🤷♂️
You should dedicate a video to the greatest of Amstrad computers ... The CPC ... by the way do you know if there is any chance this light pen is compatible with the CPC 6128 (which can work with C/PM too). Cheerio!
There is an almost identical model for the CPC yes, but different software. You can find them on eBay very occasionally.
i would like to see this piece of technology adapted to modern computers, instead of depending of a touch screen. i had see one made from a infrared light and a wiimote.
The closest thing in functionality to a light pen that currently exist would likely be a digitizer with a pen shaped stylus, either in the form of a monitor with a digitizer panel built in, or a tablet computer with that sort of functionality.
@@Ts6451 sadly it's not a technology that is strongly pushed for upgrades
D O G G O
Whats the puppies name?! Or did I miss it in the video?
Now we just need to get Keysight Labs to give you an oscilloscope. So you can find the problem and only change what you need to.
I wouldn't say no!
The rework tools look professional grade - and given what you shared about LadyFrantic I'm a little surprised you don't have an oscilloscope.
Cool video! Should have called it Lightpuppy though... :-)
You're completely wrong. Inside the pen there are thousands of ants that look at the screen and then scurry through the cable and yell at the CPU
I knew it! That's what the puppy was licking. 🐜
Thousands of ants scurrying through the cable? Utter tosh! Ants are far more organised than that!
When the ant at the tip of the pen sees the pixel light up, he shouts "NOW!" back to the ant behind him, and so on until it gets to the CPU.
No inefficient scurrying required.
Although I suspect some new ants will be required now, since the pup probably did consume at least 50...
She does like ants! #protein
That is a very nice looking dog. What breed/
Also nice breakdown of the amstrad for us USicans.
Thanks! She's a Lab Shepherd. 🐾
Here's hoping she behaves when she gets bigger. Also as a thing from experience with larger dogs If you let them on your lap when they're little, they'll generally keep doing that when they're bigger and not understand they don't fit anymore.
Oh I want her to!
Uhm what was on the screen during the super slow motion segment? Some kind of anime? You sneaky 😁
Just a cartoon 😬
Dident Commodore 64 do a light pen in 1983 i live in Australia and paid $500 aus for one it had a dataset tape drive and a light pen
Not an official one but yes there was one 👍🕹️
20:28 I am guessing this is an Amstrad limitation? I think the C64 and Amiga know exactly which pixel is being pumped out in realtime. Unlike the PC, Apple, Mac and ST, those Commodor e machine s have Sprites. On the fly pixel comparator circuits have to know both X and Y coordinate s in order to do their magic. So those machines would have ha d simpler lightpen hardware.
can you list off all the ic's on the board
Hope this helps photos.app.goo.gl/Q1jYnJCWogiwuYqy6
Is 9-bit guy the 8-bit guy's older brother?
Yes but he's only a bit older
The whole time I was thinking, "at least it's not drive F."
Great minds...
2:57 I always thought it was to tie the user into a proprietary format which Amstard had a large share of (maybe total, I can't recall anything else using 3inch) - a bit like Sony did with their MemoryStick variants.
8:30 Joke or typo? The (i) card reads "9-bit guy".
The extra bit is for parity!
@@RetroRecipes That's what I was thinking. Either that or a Stop Bit, (or 7E1), or older machines that had 36-bit words and a quarter-word was the smallest unit it could manipulate.
I want that puppy please and thank you.
Thanks for the video. Love the in depth hardware. I made one of these for my C64 as a kid. It's not hard, but not very good either. Noise seems to be one of the main issues. I never tried it with GEOS though. I wish I would have known it worked with that then. More here from the C64 Wiki: www.c64-wiki.com/wiki/Light_pen
GEOS with a light pen sounds amazing!