Intel 8052AH revisited part 1 - a little system archaeology

Back in the mists of time, during that period when the 8-bit system was in decline and the gradual rise of the 16-bit home computer - when the PC was still almost exclusively a Business System,
there was a corps of small computer enthusiasts who liked to play with microcontrollers.

I had expanded my home micro (a Dragon 32) beyond all recognition with a combination of wire-wrapped interfaces and recycled SRAM (and other) cards from embedded control systems.

It was all well and good but it was, ultimately, a slow and cumbersome system. It lacked the tiny footprint and the built-in features of a microcontroller.

Then in November 1987, Elektor Electronics published an article and design for a single board computer based arount the Intel 8052AH-BASIC chip. An 8052 microcontroller with a built-in BASIC interpreter.



The original Elektor Electronics 8052AH-BASIC SBC. Not mine - my board has been modified a couple of times, and is rather tattier than this one.

A board was bought and chips were purchased - and soon enough, there was a 4" by 6" computer on my workbench. It was used to power a number of projects over the years with the aid of a couple of protoboard interfaces.

Even after going over to PCs, I kept the board, carefully preserved in an anti-static bag and bubble wrap.

I always intended to re-work the interfaces, and to expand that machine - just because I can.

I also happen to have a project in mind that is ideal for control by an expanded 8052 control board. More on that when I get that far.

With the advent of low-cost PCB prototyping services, it has suddenly become possible to design and have made double-sided PCBs that are both properly produced and are not going to rot because of un-coated copper tracks.

For the last couple of months I've been on a bit of a binge designing the PCBs and a card cage to finally do that upgrade. It has been fun - that is to say frustrating as anything, and has required some finesse in obtaining the obsolete parts required for the project.

The most ridiculous aspect of the whole thing, though, is the terminal.

I don't want to use my PC as a terminal for the machine, so I am building an embedded serial terminal with a VGA output. It uses an ESP32 .... a 32-bit, multicore microcontroller that outclasses the 8052 in almost every way possible, except that it isn't a bus-based system.

I intend to publish the project as each stage reaches, if not completion, then the point at which the PCBs are ready to be ordered.