Adding HDMI to a stock Macintosh Classic

Well, hello everyone and welcome back to Adrian's digital basement in today's video. I want to play around with this a little bit, it's the rgb to

hdmi

, an open source project that allows you to take a Raspberry Pi along with this top hat board that has a cpld. and convert analog signals or retro computer video signals basically to HDMI. I showed this in a mail call. This was submitted by aaron who runs the retro hacksack channel so check out the description. The video in the description below I'll link to that video so you can see it, I kind of show this a little bit there.

I've also done some work on this with the laser 128, but what I really want to show is if I can get this to work with a Macintosh. Classic, you can also notice this Sony Trinitron TV on my desk. I have a series of videos on the second channel here or take a look at some cool TVs like this one, so check it out. I'll put a link in the description for that. so you can jump on my second channel if you haven't already anyway without further ado let's get straight to the point. One thing about these old Macs is that they don't have any video output, not without special cards that aren't. very common nowadays and even with those special cards the video output is not standard, but on a machine like this, which is actually good, the case is also a Macintosh

classic

, but there really is a Macintosh

classic

here because it is a combination of several very classic machines.

The classic one and two machines don't have an expansion slot, so there's actually no motherboard here, so I'll have to find one to put in here, but the classic one and two machines don't even have a built-in video expansion. so now there is no way to connect an external monitor to these. If you've ever seen any of the old Apple keynotes from back when the Macintosh was a new computer, apparently they had a way to get Macintosh video from one of these. on large projection screens, I'm not quite sure what they were doing to make that happen, but I'm thinking I can use something like rgb to

hdmi

here to very easily get the video output from this and display it on my monitor now, why what should i do?

I want to do this, you know, who knows, is there really a reason? No no. I guess if you had a bad screen and wanted to replace it with an LCD, you could use this internal to the computer and put an LCD screen in here. replace the crt and that would work or if you are like me and maybe want to display classic mac video on a larger screen you could do that, you could put it on your 65 inch OLED screen if you wanted or also another possibility is maybe video. Capturing is something you want to do.

I actually have an Elgato USB 3 capture device in there that I intend to use on video to better display video from computers rather than having to shoot the CRT which looks pretty terrible, so let's see if I can get that done. This works with Mac's first step: open it with the lid removed from the machine. I have inserted a classic Mac motherboard. I like the classic motherboard for this type of testing, specifically because it can boot from the ROM disk, which is very useful. Because there is no hard drive or floppy drive in this machine, as you can see, I'm just going to turn this thing on to make sure it still works.

I am holding down the xo option command which I think should boot from the ROM disk and I have installed the battery on the board so once this computer boots I can access the boot devices and set it to permanently boot from the ROM disk to do it without having to hold down this awkward key combination. There it is, actually. booting like I said there is no hard drive or anything here just a big empty space there are boot devices and we choose the boot disk for the rom drive while I'm at it I'm going to lower the brightness the crt is very very bright . very loud, so now if we turn off the computer, wow boy, this mouse doesn't work very well, at least not without a mousepad, turn off the machine and wait a moment, turn it back on, it should go straight to the finder without having to hold held down.

I said without holding down the awkward key combination, that's good advice - it's booting right up so let's talk a little bit about the way rgb to hdmi works, as I mentioned before it's a raspberry pi zero I guess you could use any pi. but this is the one you are running and it has an OS like bare metal, it doesn't just run linux like a normal pie so it boots very quickly, this at the top here is the hat, it's called the hat because it's on top the raspberry pi board and it's basically what digitizes the video signal that's connected through this nine pin connector here, but it could be anything, it actually digitizes it and sends it through the gpu gpio pins to the pi.

There are buttons here to control. the menu and such, there is a reset button, a couple of LEDs, but the cpld is doing the heavy lifting like clock synchronization and when I say clock synchronization, the horizontal and vertical synchronization pulses that come through this cable here, everything must be perfectly synchronized. so that the digitized signal is pixel perfect and I guess the cpld actually makes that happen, so by default the cpld board here, when you just have one cable connected like this, is set to capture digital signals, so what is rgb as in red, green, blue, but if you think of digital rgb, you're thinking of cga or ega and really what that means is that all the signals that come in through this connector here are five volts, the various video signals for red, green and blue, there is a intensity bit and the horizontal and Vertically sync well all the five volt signals on the Mac, the motherboard here goes to the CRT that is connected to this analog board here through of this cable and this cable here, all the signals that this Mac generates are also 5 volts, so the video signal that This is a monochrome machine, so it's just one bit of video along with the horizontal sync and vertical.

They're all five volts, so in theory all we have to do is connect the motherboard output to this device on the horizontal vertical sync pin, so that's two. the video signal pin, so that's one more pin and ground, so we really only need four wires. Now this is ready to accept rgb. I'm just going to connect it, I think, to the green input here, which is kind of in common use. a monochrome signal and then you can set the palette to just say I'm looking at a black and white source and then we have to adjust all the timing and stuff because the timing it uses is not standard like cga or a lot of other computers but this is so flexible , this rgb to hdmi, this project is so flexible, this should work, so the first step to see if I can get this to work is that I need to take out this analog board so I can transmit those signals from that board to the rgb to hdmi if you want To see more about how to repair these types of Macs or take them apart, check out my Macintosh repair marathon series.

I went through several of these Macs. I took them apart, swapped parts to make working machines. In fact, this power supply board. it is not the one that originally came in this particular chassis. This was one of that original repair series and I have problems with the caps written on the back because yes this actually had some problems. Capacitors with many leaks. Oh, I think it's two screws and this. comes out, I had very leaky capacitors and changing them initially did not solve this problem. I actually had to soak this board in alcohol because a lot of electrolyte had gotten into the pin holes for the voltage regulation on this port it was causing all kinds of problems, but once I soaked it in alcohol and then used compressed air to remove all the alcohol and juice from the capacitor, it worked perfectly since I have to add the disclaimer that it doesn't work inside monitors and CRTs unless you know what. what you're doing there are high voltages here especially if you have mains connected that could be very dangerous for you so let's take a look at the wires that come from the connector that comes from the motherboard that goes directly to the board analog.

Here now you'll notice that I already have these wires soldered here. These are actually the signals I need for this experiment. These are here not for this experiment but for a different one where I was using a Raspberry Pi with an emulator to control this. board directly and the crt on the mac without the original motherboard, the idea is that you can run retrostation and emulate a mac or any other computer, but display the video on this crt, unfortunately that experiment didn't go so well, I put some posts on Twitter this was a while ago I did this experimentation I think maybe it was last year or even the year before the problem is that the dpi video output on the raspberry pi those are the videos on the gpio pins has a lot of limitations for the clock that you can use and frequencies and things like that and this analog board requires very specific timing it's not wide range like a vga monitor where it supports all types of frequencies it supports one frequency, one refresh rate, all of that has to be exact and unfortunately the cake just can't do it properly without problems.

I won't go into all those details, but that's why they're here because I actually had it working, but it just didn't work properly, not at all. It's pretty cool, but since these cables are still here from that project, I just need to connect little extension cables that extend them out of the machine and then we can try it. The only thing I don't know is that I'm not sure. which wire is which, so we're going to have to go to the schematics to see which of these wires is actually which signal, so I can write it down and wire it up correctly, so I have the Bowmark schematic. for Mac Classic and here I think we are on page two, it shows the various things that we need, so there is a brightness control that we are not going to touch and here we have 5 volts peak to peak, it is the composite video signal. now it says composite, but the reality is it's not actually composite, it's just the video signal, but 5 volts peak to peak means it's just regular digital rgb, same as cga, so it's fully cpld compatible which is on this plate.

Next we have horizontal sync. which we definitely need and then we have a vertical sink which we also need now the polarity of these can be an issue, but I don't think so because I think this project is so flexible that it can handle the various polarities that we will encounter. That is known once we connect this, from these three signals we will also obtain a ground wire. I need to know what colors are and the colors are written here so w for white v for violet and g and I think it's green yellow or not that's gray so here is green yellow which is like a green wire with a stripe yellow.

This is for the sound. We're not going to connect it, so I think I need to find a gray wire. Of these wires that I have soldered here, I have the brown one connected to the black wire that is going to be grounded. I have the red wire that goes to the white wire according to the schematics. The white is the video signal and then the orange wire goes to the gray with no purple wire, the purple is horizontal sync and the yellow wire goes to the gray wire which is vertical sync so I'm going to write this on a Google Sheet to keep track, so we have white. which goes to the red, the black wire goes to the brown wire, the gray wire, as we just determined, which goes to the yellow wire and the violet wire goes to the orange and these are the short little duponts that I have there now.

I'm going to hook up this extension cord, come on, focus, we go up there and I just need to write these colors. I didn't have one on hand that was the same colors, so I'm going to make the ground the black wire and then I'm going to make the white wire on the extension be the video signal and then I'm going to make it oh, that's weird, They are exactly the same colors. I'll have the gray lead the v-sync and I'll have the purple lead the h-sync. It was completely by accident that I chose the exact same colors as those coming out of the motherboard when entering the analog board.

That's curious. There's one more thing I'm going to need to put on the spreadsheet and that's the VGA pin and that's it. because on this device here this nine pin connector I have it set to the same pin as VGA so to know where to plug things in I'm going to write that in as well so that pin one is ground we absolutely need that so I'm going to write cga here so the ground wire goes to pin one and then where is vsync vsync on pin 9? We have hsync on pin 8 and of course the video signal.

I'm just going to connect this to pin 4. So with this information in the spreadsheet, I'm now ready to grab this 9 pin connector and this cable. I'm going to cut these ends off and weld it right here and then we can test it and that was.It's pretty quick and easy to solder this. I'm not going to put a hood on it and make it perfect if it works. I can do a better job of plugging this in permanently, but this is just for testing and now. It's just a matter of connecting these Dupont connectors together and these are knockoffs from China so they're not always the best quality so the white wire goes to the red wire.

So I made my little spreadsheet to help me keep track of the purple wire. It goes to the orange wire and the gray wire goes to the yellow. Now I'm just going to put this Mac back together. I'm going to make sure everything still works so that the Mac continues to work perfectly. I don't have this plugged in yet so I'm going to power this up first and use a power bank to do it. We should get the video output on my HDMI monitor here. Great, so everything works. There's the menu that I'm going to plug into this and let's see what happens, hopefully I don't have any smoke, so from the beginning we're looking at a little image so we can see back here that it's definitely picking up the

macintosh

, but it's definitely not it runs at the right resolutions and stuff like that, so I'm going to play around here and try to make this look good.

There are a lot of settings here and I'm not going to go through them all. There are many other videos on this, but I'm going to see what I can do to make it look good and after a lot of tweaking, I'm ready. Look at this. I'm going to turn on the Mac to see that cross hatch pattern is what's there. on a Mac Classic, when you turn it on, you never see it and there's the pixel-perfect Macintosh video showing on HDMI. If I look at the menus, I see that everything is very synchronized, open this and yeah, it's amazing, I mean.

I don't know what else to say, I love crts, don't get me wrong, I have a lot of crt videos on the channel, everyone knows that, but on the other hand, things like this are cool and I think for this video I'm going to try to split the video , capture the device, the old elgato, let's see how this looks captured, okay, hopefully, this should work. The Macintosh video outputs through my cable here to the rgb to hdmi, the hdmi cable goes from here to the elgato. hd 60s capture device and then the hdmi from this connects to the monitor, the usb 3 cable goes to my laptop that is off camera and is recording right now and here we go, I'm going to turn on the Mac, let's see what we get.

Okay, so the computer, the laptop that's there, I see the video being captured, so let's hope we have a pixel perfect Macintosh video capture. Now one thing I'm noticing is that there seems to be a line of pixels that is somehow duplicated or something, yes I can. just do it with the mouse pointer, you'll see right here that's not the mac, that's definitely there somehow, I'm guessing it's in the raspberry pi settings, so I'm going to open up the menu here so I can show you all the settings I'm going I'm going to talk to the maintainer of this project Ian and I'm going to upload I'm going to give you the configuration file so you can upload this and this will be part of the distribution, but in case that doesn't happen when you see this, you can put these configurations yourself , so here we go, my geometry menu.

I'm going to use the mouse pointer on the Mac, you'll see all the settings here, a really important setting. This is 15.6672 megahertz for the clock rate, which is what the Mac runs at. The lines for the box are 370. The line length is weird, it says 1024 because I had it set exactly for the length of the line, which I don't know. I remember it's not 512 because it has the front and back porch there, something like 570 or 560 or something like that. I don't know why the default value went back to 1024. I'll fix that, maybe I forgot. To save the setting change, I made some other important settings: It's a positive horizontal signal pulse, but it's a negative vertical pulse and what's awesome is that this project allows you to set exactly the polarity of those pulses that it usually worked with, actually with it set to more. h and plus v, but because I wasn't starting the sink in exactly the right place, I was starting it at the end of the sink pulse instead of the beginning, it was cutting off several bottom lines of the image, but with it set correctly, now works perfectly in the sampling menu, we have one bit per pixel, which of course is important because we are running it with one bit per pixel, there is no color, I guess you can have the video signal in any of the rgb panoramas rg or b and you will get black and white, but of course I have it in green, if I change it to four or eight bits per pixel we will get a green image on this machine, the frame rate is 60 hertz, but it is actually 60.15, which is the actual frequency at which the Mac runs with a one-to-one pixel aspect ratio.

Now the aspect ratio is not quite right because this Mac is not actually one to one due to the exact resolution which is 512 by 342 I believe. 512 by 384 would be one-to-one, but the original Mac doesn't work in one-to-one. I'm going to try adjusting the line length to be the correct line length again. I must have changed it and then forgot to save my settings, so the correct line length at least on the Macintosh Classic and I'm sure it's the same on all Macs is actually 704, so let's set that to 704, that's it, oh yeah, I was pressing the looking back button on the feed summary clock too much.

The error is now 27 parts per million, so it's a lot better than it was and it didn't fix this weird extra double line that happens here in the middle, so I'm not exactly sure what it is. I'm going to change the scale. from auto to something else, I'm going to change it to soft interpolate, okay, so the aspect ratio is now much more correct. Well, it seems to be more correct and also that extra duplicate pixel is gone, so really that setting if you're going to run in full scale mode, which is what I was using auto versus smooth mode, it's totally up to you.

I like the way this seems to be honest for two reasons: the aspect ratio is now correct, but the other reason is that the size fills the screen correctly too, there are no longer borders on the top and bottom, it literally goes straight to the edges, it's so cool, let's turn this off and plug in a dirty device so we can boot. to something other than the ROM disk, here is the scuzzy to SD and I have a 25 pin connector here so I can plug it directly into the Mac and the nice thing about when you do it this way is that on most Macintoshes dont do it.

I have to provide power to the scuzzy to the SD card and that's because the termination power coming out of the Mac supplies five volts through the scuzzy cable is actually enough to power this thing up, so I'm going to power it up. You'll notice the light is flashing there and that's because this thing is actually powered with an SD card okay so we've got some games here let's see where my favorite crystal quest is and you can see a perfect screenshot of this game running on real hardware though how. The good thing is, of course, this machine is slow, very slow, here we go, oh, there are all some of my scores.

Yes, I actually reached level 38, the first score. I mean, I did it a while ago. Now the sound you will have to listen to. My microphone and I don't have a mouse pad, so this isn't ideal if you haven't played this game before. I highly recommend it. It's so much fun when I was a kid. I played this game a lot. You have to push. the space bar to activate your smart bombs, which is right there, is also a color game, but I haven't hit anyone here. I generally don't try to shoot things, I just shoot them to get out of the way, so that's glass. search on an hdmi capture from real hardware can anyone tell me if that has happened before?

So yeah, this is working incredibly well. The rgb to hdmi project is incredibly cool. I can't say enough about how great it is and I have thoughts on others. places where I can use it to output hdmi on those too if it can work on this because of the flexibility of rgb to hdmi it can work on tons of other older machines so I want to thank again aaron from retrohack shack for providing me with this rgb to hdmi, I definitely need to go find more of these to make. I think uh, Noel at Knoll's retro lab ended up just making some PCBs so he could make them himself.

It's an open source project, so it's completely something you can build yourself if you can't find someone to sell you one that's already made. It has some surface mount components, so be prepared to do some SMD soldering. Anyway, I hope you found this video interesting. I know I had a great time doing it. If you did, I would appreciate a thumbs up, subscribe to the channel, don't forget to check out my second channel and I want to say a huge thank you to all my sponsors who have been supporting me and it's absolutely amazing, you'll see. his name moves up on this side.

Hopefully I'm pointing the right side because I always point the wrong side and I put your comments in the comments section below and you know all the other YouTube stuff, which is all the usual stuff and that's the way it's going to be. Stay healthy, stay safe and we'll see you next time. Bye bye. Look, this is crazy.