This is a rather bizarre [[8bit Printer Ports|8bit Printer Port]] solution. Aside from the 8th data bit, it doesn't come up with any other extras: Data is only one-directional, and only Strobe and Busy control signals are implemented.
Compared with the much older single-wire [[Happy Computer 8bit Printer Mod]] (1985), the Amstrad Action approach is terribly overcomplicated. And aside from Another downside is that it the external circuit isn't even backwards compatible with normal 7bit printer software.
== Technical ==