Recent content by DougIngraham

The vendor selling just the one machine didn't include any details. The one with the 4 machines I emailed and got to add more photos. The comments below are about the machine shown from them. Also missing is a console interface and some sort of access to any other peripheral. And without a...

What I remember is that a disk is considered inserted if the sector holes are being seen as the disk turns. This works in these drives because the spindle always turns. If the cone isn't clamping properly or the belt is slipping, or maybe the sensor isn't sensing. I've got one that has to...

If I am understanding you correctly then the answer is no. The DECmate computers are intended to talk to their internal video memory when a 604X IOT is seen and receive keyboard input from the attached keyboard when the 603X IOT instructions are encountered. It is not possible to make OS/8 or...

Consumer 3D printing can be broken up into roughly two groups with some overlap. A tool for making parts. A hobby in and of itself involving the seemingly continuous upgrades to the printer systems. A friend of mine who introduced me to 3D printing and had 3 printers was firmly in camp 2 but...

The Ideamaker slicer is another good one. I have not tried but have had the Orca slicer recommended to me.

As opposed to other types of ROM? Pretty much. There is a floating gate in the EPROM which gets a charge applied when programmed. As time passes this charge diminishes or bleeds off. The UV eraser light causes an acceleration of this. I think the some of the 2732 parts suffered much more...

Even though you were able to read out the EPROMs and verify they match does not mean the VT100 can read them at speed. One of the problems is that as time passes the access time gets longer and longer. You can present an address and eventually the correct pattern will show up on the data...

From your new info I am changing my mind and think it must have been an 8/i or an 8/l. This is because of the chassis outside the CPU. This would be the device controller chassis connected to the CPU via a set of Posibus cables. This does not exclude the 8/e because there is an interface card...

In 1974 and 1975 there were three possibilities for 8 models that would have been TTL compatible. The 8/e would be the most likely as there were many more of them manufactured by that time than the other models. The 8/i and then 8/l would be next. Both of those were out of production by 1974...

Volker, DEC originally used two washers to make the spacer fit. They used an assembly order trick when putting it all together to make it go smoothly. I spent way to much time when I last replaced the fans figuring it out. The spacing on currently made fans is enough different that I ended...

Looking at what I can this was off in the weeds at the point the photo was taken. There is no way it should be executing at that location until after OS/8 is up and running. I look forward to hearing what the diagnostics tell you.

I agree that the ICs and placement seem way too similar. It is clear that the PCB is routed differently so not a direct copy of the PCB artwork. Since you can't expand memory beyond 4k without an M837 (or an M8317 in an 8/a), was this one of those situations where DEC would not sell an M837...

I appear to have confused myself. Somehow I thought E15 was a DEC384. It looks like the Signetics 314 is a 7 input NOR gate. The pinout looks correct so is probably the right part. What is the diff between the no suffix and the A suffix? The forum software let me correct a mistake in my...

Volker, Good job finding the problem! I see that E15 decodes the OSR portion of the operate instruction. 7404 actually 1111XXXXX1X0 is the pattern it is looking for. Did you have a spare DEC384 to replace it with? This would best be described as a 7 input AND gate with inverted inputs from...

From the electro mechanical standpoint I would have preferred the reed switch unit. From an esthetic standpoint I would prefer the Reed switch unit. It just looks better. But I bet it cost quite a lot more as well. It will be interesting to know what broke?