In this weekend, I'm doing a small inventory checks of old computer-related stuff in my collection. To find what works, what doesn't, what has doubles, what can be sold or exchanged. Taking photos and making list of everything, sometimes with descriptions.
But returning to the topic. Today I opened a box with "PRINTER PORT ACCESSORIES" text and, among parallel port switches and serial-parallel converters I found a 256K printer buffer with 2 printers-one computer switch, made in early 1990s by some Polish company. Much heavier than Taiwanese ones and requiring 500mA power supply. I decided to open it and see how it works and what takes half an amp. I expected SRAM, some TTL, I've previously seen digital printer switches done entirely on TTL chips, maybe some microcontroller.
No, I was totally wrong. There was, stuffed on two PCBs, a complete ca. 2.5MHz Z80 system with 256kB of dynamic RAM (aligned in switchable banks) and 16kB of ROM! Port switching with 8255! Spectrum has 16kB of ROM! This is a printer buffer which theoretically can run BASIC!