Many things have combined to make very high-frequency RF gear much more common, cheaper, and better performing. Case in point: [dereksgc] is tearing apart a 20 GHz low-noise block (LNB). An LNB is a downconverter, and this one is used for some Irish satellite TV services.

The scale of everything matters when your wavelength is only 15 mm. The PCB is small and neatly laid out. There are two waveguides printed on the board, each feeding essentially identical parts of the PCB. Printed filters use little patterns on the board that have particular inductance and capacitance — no need for any components. Try doing that at 2 MHz!

The LNB is a single-band unit, so it only needs to worry about the two polarizations. However, [dereksgc] shows that some have multiple bands, which makes everything more complex. He also mentions that this LNB doesn’t use a PLL, and he’d like to find a replacement at this frequency that is a bit more modern.

After the teardown, it is time to test the device to see how it works. If you want to experiment at this frequency, you need special techniques. For example, we’ve seen people try to push solderless breadboards this high (spoiler: it isn’t easy). Maybe that’s why many people settle for modifying existing LNBs like this one.

Since the latest release of ‘piolib’ we can do things like drive NeoPixels on any pin on the Raspberry Pi 5 which rocks, and means we can tackle the next, more complex, project: driving HUB75 RGB Matrix displays these require even MORE timing freakiness: using 10 pins, and ‘manual’ PWM means we have to constantly blit out the color dithering. Historically this was done with mmap’d memory to the GPIO controller bitbanging, which required a full core and could jitter depending on load. But now we can use the PIO peripheral! We can drive massive display arrays at high speeds and color depths using just about any pins. The future is looking bright – video.

A different one today! Cromemco was founded in 1974 by Stanford Ph.D. students Harry Garland and Roger Melen to develop a series of peripherals for early microcomputers, such as the Cyclops digital camera and the Dazzler color graphics interface. In 1976, they came out with their first full microcomputer, the Z-1, which used the same chassis as the IMSAI 8080 but fitted with a 4 MHz Zilog Z80 processor instead of the Intel 8080.

The Z-1 was very flexible for the time, with 8 KB of static RAM and 22 S-100 bus expansion slots. This allowed the computer to immediately function upon power-up, without manually loading a boot program. Cromemco’s vibe from what I could read was a commitment quality and reliable system, its systems found wide acceptance, and by 1986, more than 80% of major-market U.S. television stations were using the system for news and weather graphics. The company continued to keep going until it was acquired by Dynatech Corporation in 1987.

Adafruit team member Franklin’s story …

After reading Byte magazine and Jerry Pournelle’s Chaos Manor articles I bought a Cromemco motherboard, (Cromemco named for CROthers MEMorial Hall – the Stanford residence where the founders lived, came into existance in the mid 1970s, and grew to become a major player in the S-100 business systems market.) Cromemco began by making S-100 boards. Their first system called the Z-1 was based on an IMSAI chassis with Cromemco boards, however they quickly moved on to building their own complete systems. I hand soldered the S-100 daughter boards and placed them in a TEI case but had no way to program it. Jerry wrote about Tony Pietch who was in Cal Tech close to me so I looked him up and contacted him. He agreed to burn ROMs for XMON and, with XMON and Tarbell Basic I had a working computer. That was sometime in the late 70’s.

So of course I needed to find out more about Jerry Pournelle and Chaos Manor! One of the first bloggers!

Pournelle’s journalism focused primarily on the computer industry, astronomy, and space exploration. From the 1970s until the early 1990s, he contributed to the computer magazine Byte, writing from the viewpoint of an intelligent user, with the oft-cited credo, “We do this stuff so you won’t have to.”He created one of the first blogs, entitled “Chaos Manor”, which included commentary about politics, computer technology, space technology, and science fiction.

Have first computer memories? Post’em up in the comments, or post yours on socialz’ and tag them #firstcomputer #retrocomputing – See you back here tomorrow!