Recent Posts

Ben Sinclair's avatar

New DLV11 Serial Board

Someone on the cctalk mailing list was kind enough to send me a known working DLV11 serial board. This one passes the interrupt test and seems to work!

My CPU test is still failing, but I've at least eliminated one potential problem.

Ben Sinclair's avatar

MFJ 9420

I boxed up my Icom IC-7100 to sell, as I want to swap it for the new Yaesu, so I've been using my MFJ 9420. The 9420 is a cheap 10W SSB rig that works surprisingly well!

It has a smooth analog tuning knob, a smaller fine tuning knob, and that's about it for controls. The top firing speaker actually sounds good too.

Paired with my MFJ loop I was able to make some SSB contacts today, and even got into a pileup or two.

Ben Sinclair's avatar

A New Project

I've just started building my own 6502-based computer, similar to computers built by hobbyists in the 1970s.

I selected the 6502 CPU because it seems simple to understand, there is plenty of documentation, and a large community exists around it. The chip pictured is actually a 6504, which is a 6502 in a smaller package. It won't be able to address as much memory because it lacks the pins to do so, but it will be easier to wire up.

Hopefully it will work!

Ben Sinclair's avatar

My IBM System 360

I recently purchased the name plate from an IBM System 360, which is one of my favorite machines. There are only around 30 known systems remaining, so I was happy to at least find a name plate.

One interesting note about this purchase... I ran across a mention in Resurrection (a computer history magazine) about a huge warehouse of System 360 machines in Texas. The IBM Hursley Museum was in touch with the owner, but he stopped talking to them.

My name plate was shipped from Texas, and the seller said he was parting out full systems from a warehouse, so it had to be the same person. I gave the museum any contact information I had, and hopefully they will get in touch again. These are very rare machines that need to be saved.

Here's a photo of a colorful IBM System 360 installation. Note the name plate above the console in the upper left.

IBM System 360

Ben Sinclair's avatar

The PDP-11 AUX Switch

One thing that tripped me up with my PDP-11/23 was the aux switch on the front panel. I assumed it simply controlled the auxillary AC power plug on the back, which is what some of the documentation says. You might use it to power an RL02 drive, for example.

I didn't realize that it can optionally control the line clock interrupt. My system suddenly started acting very strange, and was no longer able to boot XXDP via the TU58. It turned out I had flipped the aux switch, which was setup to control the line clock interrupt. After some help from the cctalk mailing list and the documentation, I found that the BVD11 can control the line clock interrupt via software if you set a certain jumper. Now I just leave the aux switch alone!