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(the moment you realize how a 555 timer can be used to turn an analog signal into a digital signal) That's brilliant. Absolutely brilliant.

Dave, you should make a video series on these nice but rather complex old PC schematics in detail explaining every single bit of it. As we saw in this video, there are many many interesting parts. Btw. this joystick technique (hardware) is used even today in RC transmitters.

Thank you soo much for all the interesting videos. Love it so much. Greetings from Germany, Düsseldorf

BBC had an ADC as it was intended for other educational uses - datalogging etc. It was labelled as an analogue port, not joystick

If I recall correctly, my TRS-80 Color Computer used a binary resistive network (which was a true analog output) in place of the ramp generator mentioned in the video. Since the software could control each resistor, it would do a successive approximation and stop once the comparator trigged (after backing off to find the least possible value that still triggers). Therefore, there was no need to read a pulse width signal since the software already "knew" the output value. That was when I first learned that an analog output + comparator could serve as an analog input.

Man your comment is uplifting, great video thx

Great videos Dave. Thank YOU.

From Wikipedia on the Apple ][, which premiered in 1977 (PC Jr was 1983): "Rather than use a complex analog-to-digital circuit to read the outputs of the game controller, Wozniak used a simple timer circuit whose period is proportional to the resistance of the game controller, and used a software loop to measure the timer." Sound familiar? Sound earlier? en.wikipedia.org/wiki/Apple_II

Yeah I remember how clever these old joysticks were. I remember fiddling around forever trying to get them to zero out properly (without randomly drifting in one direction). Then you finally get it right and on the next reboot it was back to drifting again! Thank the guy that came up with rotary encoders instead.

Davecad supports two screens now? :O

the 555 was the 1st chip or ic that I used as a kid. 101 use's for it.

The '77 Apple II did it like that too: trigger the 558 in one shot mode and use the µP to count until the pulse ends.

Another great lesson, thanks Dave :)

Steve Wozniak (Apple II) first came up with the RC design. In a presentation, he said something about this being cheapest way he could think of. The timing was all done in software.

It was interesting to see how these little guys worked and explains a lot about how inaccurate the joysticks were back then! I can remember playing games on similar PC's back in the day and all of sudden your character would start walking in the opposite direction to what you'd selected on the joystick. I always thought the software was the cause, but I reckon it was just the slow speed's of the PC and not being able to scan the joystick ports quick enough with the shared resources.

Wow, I remember the days playing with a joystick like that on a Tandy 1000. Good Times:) Thanks for the video about the inner workings!

cool video ! thanks... I wish I had such an interesting electronics teacher back in the days

Thanks for following my suggestion/question ;) (unintentionally probably) Love this little circuit, so easy yet so extremely useful! Makes you realize how over engineered ADCs actually are.

I use to program games in DOS, and had to write a calibration routine as CPU speed was an unknown so one had to get the min and max timing and convert it to 0-255 8 bit value

The Amiga used hardware to count how many scan lines it took to charge a 47 nF cap through the joystick pot. You'd write to a control register during the CRT vertical blanking period to discharge the cap and start the counters and then read the pot register when the next vertical blanking period started, followed by setting the control register again to repeat the process every frame.

Nice one, Dave! The venerable 555. I started making transistor multivribrators for my projects in 1972. In 1973, I made a Sputnik beeper for a model rocket using transistor multivibrators. I still have my first 'breadboard' and the rocket beacon, still working. After that, the LM 555 came out and that was a godsend! My first real project was making an LED blinker for a phony security camera body. Since I was the shop tinkerer onboard my ship, I made the blinker for a case with a phony glass lens that looked like the security cams that were available for that day. That seemed to stop the thefts. You open the door and one of the first things you see was the blinking LED on the phony camera body. Later I got an AC synchronous motor drive controller for my telescope with joystick. The circuit in that was MUNTZ unstable and I used a 555 chip and a regulated supply to remedy that problem. The autoguider socket and add-on was added later. I still use it to photograph the night sky.

#1054 Should be about our favorite 50MHz 1Gs/S 4 channel Digital Storage Oscilloscope, with "upgradable" Bandwith, memory and math functions.

Great videos, add some specific topics also to have some deeper knowledge. Although all your videos are great. 😀👌👍

Back in the day, when technical solutions were crude but exciting. Today: Pick a microcontroller with USB and a sufficient number of ADC channels...technically much better, but booooring ;)

What an amazing idea. I wonder how precise was it because the software timing, I couldn't make a wav player without interrupts on an esp32 :D

The Vectrex used a similar method, but using the main DAC instead... The CPU sent out a few incremental values to the DAC, and when the voltage from the DAC matched what was on the pot in the joystick, a comparator then just outputs a High signal to a digital input pin. With the use of a mux chip (4066, IIRC?), it meant that they could just one of the relatively expensive DAC chips for the X/Y/Z, and both joysticks. (the "Z" axis on the Vectrex was just the beam brightness.) Quite a few clever tricks were used to cut costs back then. Sadly, cutting costs these days often means manufacturers using crappy plastics etc. Bring back the heavy IBM cases and tank-like build quality, I say. :p (for non-portables, obviously. lol) Dave - It would be fantastic if you could get hold of some of the MIPS era SGI machines for a teardown. I could be wrong, but I don't think you've covered one of those as yet? Huge amount of engineering went in to the SGI Octane / Indy / Onyx etc., and they had a huge price tag to match. I had an Octane (MIPS R5000) and O2 for a few years. They weighed so much, I was slightly worried about the floorboards. lol

The joystick looks suspiciously like the Kraft joystick. Likely just rebranded for IBM. Nearly identical circuit used for the Apple 2 in 1977. A 558 timer.

Love the comparison between the two timing circuits. I had a joystick that never returned dead center back in the 486 days. Calibrated it and trimmed it but my spaceship would always slide about on is own! >.< Nothing beats mouse and keyboard anyway.

The joystick was made by Kraft, it was also sold as the Tandy Deluxe Joystick for the Tandy CoCo and Tandy 1000.

Looks just like a Tandy joystick I have for my Color Computer.

Could you do an in-depth study of how a modern Xbox or Dualshock analog stick works? And why my Joystick tester on PC shows shaky analog axes and drift sometimes?

Of note, the MCS series microcontrollers from Intel were released starting in 1982. They have built in AD converters in them and were used pretty extensively in a variety of applications. My Roland W-30 music workstation had an 8098 in it. The 8061 was primarily built for Ford for their cars, but the 8051 is a classic microcontroller in a bunch of industries. It was released in 1980. However, you're right, it would *never* be cost effective as a simple joystick read circuit. I just wanted to note that there were a quite a few microcontrollers on the market by the time the peanut was released. Programming for the 8097/8098 was a blast though, especially the banked RAM configurations. :)

DaveCAD 558 joystick schematic warms my heart. Gotta love the hex address decode, don't remember hex addresses? That's your good, or bad fortune, depends how you look at it..

Back when I started with using computers all sound cards had a joystick port built in. From a technical perspective this doesn't make any sense, but you'd want both for playing games, so it was kinda useful.

I remember I build my own gameport card for my PC on a piece of perfboard back then.... Played many hours of Flightsim 1 and Elite with it.. I think I just copied the schematics from the PC technical reference manual (I worked for IBM at the time so had access to all these books)

I owned one of them.... the Tandy one, though(for my 1000EX). The neat thing about them is that you could unlock the axii so they didn't automatically return to center. (I see now he covers this in the video - lol, with the same descriptor)

I wonder how much of a delay the timing of the 555 signal width causes to the input signal

Holy crap, saw 555 liked it!!! Bloody brilliant! Gotta say my first thought was: Meh... just stick a micro in there! Man, engineering back then sure was fun.

Vintage tech FTW :-)

Holy fuck that is beautifully elegant solution Brillian

C64 SID chip had 2 analog inputs as well. It could measure the analog values of 2 pots without blocking the CPU, with less parts needed. A "Single Slope" ADC was included in the chip. Cheap ADC in 1982.

thanks 👍👍

Hey Dave, As an industrial automation/process control guy I'd like to see a detailed video on how modern industrial transmitters keep a stable constant current loop indifferent to a reasonable (0-1387ohm) resistance.

The joystick port in the SoundBlaster, which later became the PC standard, was directly connected to the bus with a single I/O address. There was no timer, only capacitors. To read the axis positions, software would write to the port to reset the capacitors, and then read the port in a tight loop until the bits flipped. There was no precise enough timers on the PC, so the time was measured using a counter in the loop. Of course this doesn't allow any inference during the loop, which meant disabling all interrupts for devices like the keyboard and soundcard. Which doesn't work that well in a modern multitasking operating system...

Fun fact: The Tandy 1000 series, up to the RLX (which was, I think, the last model based on the PC-Jr) could use a joystick in lieu of a mouse in DeskMate.

I recall that joystick being branded "CH Products" and "Kraft".

Would you be interested in maybe making a video about an LCD controller board design? Or be able to point me in the direction of something I could read to learn more about it?

9:00 - Why did they need 4 channels? I thought there was only 2 pots in the joystick? Or was this for "controllers" that had 2 sticks?

When and how was MIDI implemented in the game port?

So the Tandy 1000 is not compatible with the Microsoft sidewinder gamepads because they use a trick to read the trigger pulse out of the analog input through the discharge transistor of the 555 timer.

I still miss using BASIC to make little jingles on that crappy paper cone speaker. Back when computers came with programming manuals.

Would it be possible to make an external adapter to convert any PC analogue joystick to a BBC micro? I don't know enough about electronics

I HAD ONE OF THOSE!!

It's a Kraft joystick. I had one a lot like that, until my little brother cannibalized it to build a steering wheel and gas pedal to play Stuntz.

I believe CH made the IBM joystick, and produced an identical product under their own brand - they may have bundled that original game card as well.

That’s exactly what an Apple II joystick looks like. I wonder who came first.

Software timing? I would have used some 7400 series counter and an oscillator that is gated by the 555 timer, then fetch that counter value and toss into a buffer for the software to enjoy. Though, it would need two 8 bit counters per joystick, and two AND gates too... But no more software timing!

Did not Apple have a joystick for its first computers? I think I remember it having a rather smooth fluid feel, it had x/y trim pots on each side. But I think the biggest thing I liked was that you could disengage the centering springs of the stick so it would stay wherever you put it instead of it moving back to center. Both x and y axis.

Does it have a what-not-gate?

RC Hobby still uses PWM signal for radio transmitter joysticks and servo/motor controlling :) 50Hz, 1000-2000us width signal. Fortunately, "drones"/multirotors are pushing it to digital communication :)

Awa, Dave, you could have stuck a signal generator on there to force the triggering. Output would go to buffer .. shouldnt cause lockup.

Please teardown ye olde Microsoft Precision Pro and show us how that 'patented optical technology' works.

I have an old Genius joystick that my mom wants to use to play Wolfenstein3D (I got the exact model she used to play when I was a kid), but I'm having trouble getting it to work with the USB adapter I found. If anyone knows of a universal or customizable/calibrating type of gameport-to-usb adapter, I'd be super thankful!

I got a free gameport joystick on the internet. I thought it would work with my Creative cards, but windows did not have drivers. It turned out to be more or less a digital joystick with an analog startup. So I made sort of a driver using various thing so it works again and is mentioned on my youtube channel. My stuff works for the Microsoft Sidewinder Precision Pro exclusively be warned.

You mentioned the tolerances on the pots wasn't that great, so I guess that was part of the calibration routine you used to have to run? It was looking for the pulse length corresponding to center, min and max on each channel for your specific stick? I always figured it was more to do with small mechanical differences causing variations in where the stick would center physically, but the values of the pots not being consistent makes a lot of sense.

I think that could be made a lot less software intensive with only 3 extra chips. An 8-bit binary counter driven by the main clock, AND gated with each output channel of the 558 AND one output line of a binary-to-decimal decoder on the main bus. The binary value written to the bus selects the channel that will be delivered via the AND gates (along with the system clock) to the binary counter which will cunt as long as the 558 output is high and transfer that accumulated value to the data bus. I don't know if the main clock would be running at a good speed for this to work but another local oscillator could be used. If you were willing to wait 256 cycles for a full 8 bit resolution position, you could queue up a joystick read 256 cycles ahead of time and do something else. Although I imagine the maximum delay would still be less than the software loop. Another bonus would be waiting a different number of clocks to achieve different resolution counts if some application favored response over precision. The sample rate could be arbitrary for each sample. You might also be able to mix the buttons in there to grab 1 axis (6 bit) + 2 buttons depending on an address value mixed with some more AND gates. I bet there are other clever ways to chain 2 4-bit counters and some extra decode logic to allow 2 axes to be sampled in one read (at 4-bit resolution). Side note: do stand-alone ADCs work this way? I always thought they had a series of comparators (one for each bit) with a precise binary sequence of thresholds. They would all receive the input signal in parallel and the pattern of comparators that were on represented the binary translation of the the analog input.

0:23-1:03 5 times "actually" ;) Now i know where did my "twice a sentence actually" came from.

And if you put an LDR you could "measure" light hahaha I did a scanner with that and a plotter

Why did they need 4 pulses from the joystick instead of just 2, one for each pot?

You can use POKE in BIOS BASIC to write to the joystick address.

Externally that joystick looks exactly like the Color Computer one. Except the CoCo used an ADC.

15:00 Isn't that integral schematic one of the more primitive ADCs?

Looks like the Kraft joystick for the Apple //. Apple // joysticks and paddles were analog and predated the PC versions.

Dave, you should start upload your stuff on dtube too.

I've lost count of the times I've had to clean or replace the potentiometers in game controllers when they start to develop stick drift, and the worst part is most people just buy a new controller when this happens.

The problem with that is 1) it takes a "long" time, and 2) you never know how long it's going to take and 3) you can't read paddle one and immediately after read paddle 2 or 3 or 4 because the readings might be wrong, IIRC

The amazing 555, is there anything that it can't do?

Woz invented that circuit in 1976 and used it in the whole AppleX series.

I'm not educated in electrical circuits at all. I want to learn enough so that I can build a joystick control system which will control a 12v trolling motor on my kayak. I want to increase the speed as I push the stick forward and go in reverse as I pull the stick back. At the same time I want to be able to steer the kayak by rotating the motor by moving the stick left and right. And finally, if I fall overboard, the motor should stop as the stick automatically goes to the neutral position. I'm guessing the type of analog joystick shown in your video might be able to do this when connected to servos or actuators to rotate the motor. Am I on the right track?

So how does a Joystick nowadays work, if there are still those? Do they still have a potentiometer for determining their position? Or are there other methods that are more clever for digitally reading the X- and Y- position of a joystick? I think maybe some capacitive thingy with two coils on each axis that move in relation to each other and change the capacity of the circuit, or something like that?

Use DOS debug and out to port 201H (if I remember correctly) that will trigger the 555 DOS debug commands montcs.bloomu.edu/Information/LowLevel/DOS-Debug.html Example in DOS run debug enter O 201 xx ( output port byte )

Ah, the 15 pin PC joystick port. Almost as ubiquitous as the Atari joystick port. Although, more long-lived I suppose. It's actually kinda surprising how many systems ended up with Atari ports or minor variations on it. To this day the best input device for most 8 bit computers (though you have to watch it with some, especially those which deviate from the Atari spec somewhat) often turns out the be a mega drive gamepad. Granted, in existing games only one button and the d-pad works; and given how the IO for most ports works (And the Atari port in particular), with custom software routines the best you'll get is the d-pad and two of the 4 buttons. (2 of the 7 buttons on the 6 button version.) It wouldn't be hard to create a simple adapter that lets you use more buttons, but as is without rewiring either the controller or the port, this somehow just works. It shouldn't, because it doesn't quite match. But it works anyway because the Sega controller expects +5 volts on a pin that according to official atari specs does nothing, but in fact is generally pulled high (eg. gives +5 volts) in most systems. The reason you can't use all the buttons even with custom software is related to this; the Sega specification uses one of the pins as a 'select' switch. Pull it high and you read Button B and C, pull it low and you can read A and Start. It just so happens that the pin chosen for this is the pin that in the Atari specification is used as the power pin. So it's always high. Which is why you get two buttons but cannot access the others; there's no software control over that pin. (There are 4 pins that can be set as either input OR output, but those are the ones that give the D-pad inputs on the Sega controller. - and in fact by default the joystick inputs on a standard Atari joystick as well. Part of why this works at all - the D-pad maps to the same pins as an Atari Joystick, and the B button maps to the atari controller's Fire button. The C button maps to what is officially an unused pin, but which IS readable in software - Except no existing software reads that pin, for obvious reasons.) Kinda weird how many systems used that same standard, or near enough to it, in the end. Nintendo's logic for how to read a game controller is quite different. Though in their case one of the things that might not be obvious is that the NES and SNES controllers have the exact same pinouts and behaviour; Obviously the SNES has extra buttons, but beyond that the only difference is that the two have physically different connectors... For a short summary of the differences, the Atari specification, while it has some variations for stuff like paddles and the like, really just treats the 9 pins as +5 volts, ground, and 7 inputs. - two are unused in the official spec, but you register an input by puling the relevant pin to ground. The Sega controllers are almost identical, barring a change in which is officially the +5 volt pin, and using up the unused pins for extra functions. That's all there is to a Master System controller, but a Mega Drive controller then uses a 'select' pin to swap between two possible interpretations of what the pins mean. An Atari controller therefore is just a bunch of buttons wired such that they pull specific pins to ground as needed. A sega controller is the same but in the Mega Drive adds a bit of logic to switch between multiple sets of buttons. (the active set pulls pins to ground, the inactive set is ignored.). The 6 button controller contains a microcontroller and uses a special timing sequence of the select pin to access the additional buttons. the way Nintendo does it is effectively a simple serial port; Compared to the atari and sega approach (excluding the 6 button controller) this is slightly more complex. But, it's not compex circuitry. The controller simply contains a pair of 8 bit shift registers, which are hooked up to form a 16 bit shift register. The console sends a latch signal to lock the shift registers into a specific state (the combination of buttons when the latch was enabled), then sends a clock signal to shift out the bits one by one, then releases the latch signal. A completely different approach, which is somewhat more complex, but also more adaptable in the long term; All you need to do to get more capable controllers is either add more shift registers or use a microcontroller in the gamepad (depending on the complexity), and redefine what format the serial data that gets returned is in. The n64's controllers have a much faster bus, and have been reduced to just 3 wires from 7 (obviously the fact that the n64's memory cards attach to the controller has implications for what the transmission protocol is capable of; But the SNES controller ports have been adapted to attach some kind of flash storage to, as were the NES ports before them.), but the principle is similar. The gamecube controller still follows roughly this principle... The wired Wii controllers have switched to using an I^2C bus, but it's still roughly the same concept... All this stuff is surprisingly interesting when you look at it up close. (in case you're wondering why I haven't mentioned anything else besides Atari and Nintendo... - well, like I said, the atari standard was VERY influential in the 80's. While a bunch of systems didn't follow the spec all that closely, they still broadly followed the idea of the port, and changes were usually just swapping the meaning of some of the pins around...)

tandy 1000 disk are found here: www.oldskool.org/guides/tvdog/system.html

Dave, I thought all of those computers of that era came with BASIC in ROM so would boot into a BASIC interpreter, well the IBM PC did. And you could have used a simple BASIC program to POKE the address of the joystick control and that would have generated the triggers you need with using game software or DOS. Something like this: 10 ADDRESS = ???? 20 POKE ADDRESS, 1 30 GOTO 20 the syntax maybe off but that all you needed. Replace the ???? with the address of the latch/controller.

I saw "55?" on the block in the thumbnail and was confused AF. Thank you for the thought-provoking clickbait.

12:50 all the way with LBJ up to 125 K

Why is this not appearing on my timeline?

I'm sure Woz didn't do it like the Tandy because he didn't like to mess with analog electronics very much

5 years too late, but you actually didn't need a boot floppy to test the joysticks: The PCjr has built-in diagnostics, including a joystick routine. Hit CTRl-ALT-INS after POST, and then press spacebar until the cursor is by the picture of a joystick, then hit ENTER. At that point, the ports will be constantly triggering to show an image you can use to calibrate the joystick positions.

The moment you realize that your Tandy TRS-80 Deluxe Joystick was an IBM clone....

Why didn't they use a DAC?

How does one go about knowing that NE558N V8407 S is generically known as just a 558 chip... with so much other stuff written on IC's how do you extrapolate what means what, i mean even date codes are written several different ways and are not always present on components, so how does one come to know weather they are looking at a modek number, part number, date code, manufacture specific model number that contains a generic model number, etc.? Is that just experience, or is there a method to the madness that is reading component labeling? My guess is it's a mix.., some combination of methods that one gets a feel for which to apply in a given component type given the rough date and type of electronic circuit being looked at by way of experience. Am I close? My current method is to just type the type of component in to a google search and try following it with what's written on the component one Alphanumeric/numeric code than the next, than the next until i get a hit, but it doesn't always work. I did this with an ac fan relay recently and got some love from google, but sometimes i get no love so any hints would be appreciated.

Love 'dem EPLS and WWCD (Easy Peasy Lemon Squeezy, Winner Winner Chicken Dinner)

Hello, do you repairs? I am a 1 handed gamer. I have 2 of the old edimensional access ben heck designed controllers. It uses like 4 universal boards so you can move these little pods into different locations. I have 1 arrangement (eventually i like to make my own permanent controller, because i think the universal boards cause issues.) Anyways all 4 of my joysticks (both lefts and rights [use as lefts sometimes with remapping]) ill show input when not being touched or not resetting to 0 after letting go of joystick. Makes playing ro oncket league really hard. I order a ps2 potentiometer but the one that is in the access controller pod has a small 32 pin connector on bottom of it that connects it to the board. I cant even figure out how to get it out of the pod, im guessing you need to pop off the joy stick pad somehow or remove board from potentometer. I be willing to pay for getting new potentiometers in my access pods

Holly smoks you can buy a 5 1/4 Floppy Brand new!!! Guess i need a Floppy drive now. Good old times!

Hey I have a question for all of you enthusiasts out there, I have recently started hobby electronics and have opened a lot of old electronics and do these old electronics contain large amounts of lead and is it a risk touching then and leaving them about, I also have 2 cats and I want to know if this is safe

The joystick looks an awful lot like a Kraft.

every game: Calibrate Joystick *holds joystick to bottom left and press button* *holds joystick to top right and press button* Joystick calibrated!!! :D

who needs micros when you have 555 timers?

Wow :D