Recent content by Roland Huisman

Using the board as-is, is a nice idea. I have piles of these 1702A roms and I have also a reader/programmer for it. I will see if I can find documentation. My first idea was to clone a sbc kind of board. But I'm not familiar with these boards at the moment...

cool :) interesting to see the clock on the background. Taking hours and hours to boot or do something interesting... It is fun, but I think I would like to build something more period correct... :unsure: And no, not a calculator ;) I guess there is a 4004 monitor from those days. (like for...

I have two boards with National semiconductor 4004 CPUs on it. These boards are from an EPROM programmer which were built into a development machine. The machines are gone, the original programmer brand is pro-log. But to be honest, I don't care about the original boards, I just would like...

Recently I had contact with one of the makers from my Mark 8. Last November I got an email with compliments of Jon Titus (!) and I sent that too the original makers of my Mark 8. Two brothers Jaap and Henk. Henk replied to me that Jaap has passed away. Jaap was the person where I actually got...

I had a few people trying to get their hands on my Mark 8 too. Trough my website, mail and forum. I don't care, asking isn't prohibited. But my answer is no. After talking to some others it was clear that a few were just people with a lot of money. Buying everything special, and after that it...

I was thinking about a similar construction for just one emulator... Maybe it is possible to make a 3D print to mount it into a SCSI enclosure... But that discussion might be better in the emulator topic itself... Regards, Roland

Okay, that gives a better idea about what is available. So what do you have for materials or power supplies? Maybe we can be a bit creative here. If you have a fixed 8...9VDC supply that can deliver about 5 amps, we can make that current limited by connecting a car head light bulb in series with...

The crowbar will trip in a few milliseconds. But this is not the way to debug a failing power supply and the thytistor might be a short circuit by now. The thyristor is not made to short that power capacitor over and over again. Fixing such a power supply needs a bit of TLC and a current...

Hi Maurice, You don't need the K303 if your M710 board version is M710H or higher. You could ask the previous owner if he has a M7810 Regards, Roland

Hi Vince, that sounds nice but let's see how things go. The older model M710 with a K303 is also fun. But finding that K303 is another thing... Nice! I've seen that page before but didn't spot the K303 earlier. The K303 seems to have three potentiometer pcb's with a capacitor on its back...

When measuring the sync I've got nice pulses. But the output from the M7050 had a different timing. Each time skipping one pulse. :unsure: No wonder it skips characters... So I borrowed the M7050 from my other PC05, and guess what? That solved the problem...! The strange thing is that d both...

So I started this topic about 3 years ago. The four M040 were the last parts I needed to make the PC05 complete again. Never found them on Ebay, but sometimes it helps to ask again. And guess what, on the same day some weeks later I received eight of them. :oops: Well there are 2 versions, and...

Tripping CB1 means your 5V power has a problem. Does it trip without the cards? Please leave the cards out of the PDP when testing a trouble making power supply! I've stripped everything out of the schematic that hasn't to do anything with regulating the 5V. What I would suggest is that you...

Good to hear it is switched on now! Mine makes a lot of noizzzzze too. That is a thing with these ferroresonant transformers. I pulled the fans plugs to hear what the transformer is doing... For reference, another 8/A on youtube, (not mine) Here you can also hear that typical buzzing of the...

The temperature protection works in the opposite way. The relay is activated, that is why the PDP8/A doesn't power up. (It actually powers up and then is switched off by the relay) You can pull the fuse from the protection circuit on the backplane, then the PDP8 will power up. Doest it work thát...