nynyny7

In all fairness it needs to be said that the libc's implementation has to consider portability to more "exotic" architectures. For example, not every CPU allows to make unaligned 32-bit or 64-bit writes, or it takes a huge penalty for such writes.

At least the drive I accidentally tried the same had a mechanical stop. Although banging the head against it 170 times or so wasn't exactly beneficial for its alignment.

Even today, one is better off not to write undocumented values to registers. True story: I had to investigate a SW bug report concerning a modern, fairly popular microcontroller. (I won't name which.) Sometimes data in RAM changed without our code writing to it. Turns out that our startup code accidentally wrote to a 'reserved' bit in a register, activating some kind of internal RAM test mode. This was confirmed by the µC's manufacturer.

Fascinating read, although I take issue with its title that implies that it's a bug in the chip. Maybe a bug in the author's code (when he wrote wrong values to the register), definitely not a bug in the chip but a feature. If you write undocumented values into a register, undocumented stuff happens. A lot of ICs have undocumented test modes that are used by the manufacturer.

I didn't measure it, but literature has a value of about 0.3 V for a germanium diode's forward voltage.

Simple: The germanium diode was the first suitable diode I found in my parts collection. :-)

A regular silicon diode will not work. An appropriate Schottky silicon diode will do the job; see the Infineon app-note in the "PPS" of the website. Also, the point-contact (regardless of the semiconductor material) reduces the diode's junction capacitance, making it faster, i.e., more suited for RF applications.

Note that you can have a fully open-source retro experience by using EmuTOS (a free operating system for Atari computers) with Hatari: https://github.com/emutos/emutos

PS: Similar product evaluations exist for a lot of components from the Z80 series, including the CPU. But only on paper, because they haven't been scanned: http://smithsonianchips.si.edu/ice/s3.htm Maybe you can convince the National Museum of American History's archivists to scan more of them.

Yes of course. It says so in the title: "Zilog Z80-CTC".