The void left by the parallel port
The parallel port was great for simple bit-bash interfacing and I miss being able to do such hacking on contemporary PCs. I remember fondly a hacking war story from the late 80s. I had just purchased a Mephisto 68000 dedicated chess computer for my own recreational enjoyment. The embedded dev lab where I worked won a new contract and the hardware dudes decided a 68000 was the way to go. Not content to wait weeks, maybe months for first hardware, I decided to get some early experience by hacking at my chess computer. Basically I opened it up, reverse engineered the keyboard scanning hardware (which was implemented with standard jellybean CMOS logic), and commandeered a couple of inputs and outputs for my own purposes. I hooked these up to the printer port of my PC.<p>Then I worked out a simple serial bit twiddling scheme to exchange bytes a bit at a time and coded it up in C as a kind of software serial port. On the PC side I ended up with something that looked just like a simple terminal that happened to talk out the printer port. On the Mephisto side, I replaced the 64K byte EPROM with a 128K byte EPROM. I changed the cold boot vector to point at &quot;my&quot; 64K, which first checked to see if the printer port was hooked up. If it was hooked up, then the CPU stayed in &quot;my&quot; area and ran a monitor I had coded up for the occasion. If it wasn&#x27;t hooked up it vectored back to the original boot code and the chess computer worked as well as it ever did. I layered a loader on top of everything and enjoyed loading simple cross compiled C programs on my new 68K computer, (complete with 16K RAM).