It was 1974 and an Engineer from the Department of Neurophysiology named Alberto Caro had designed a device for the experimental work of the department that could be controlled by our CID-201-B computer, compatible with the PDP-8, which I referred to in the article "CONCATISO. My first program.".

Due to production priorities, the Central Institute for Digital Research (ICID) did not give us what would later be named as MEDICID-2 and for that reason, with great inventiveness, the engineers and technicians of our Department set about the task of designing and building a prototype that allowed us to advance in our investigations, and in 1975 the equipment was ready.

The MEDICID-1 had digital input outputs (0/1) and analog inputs outputs using 12 and 8 bit analog converters respectively. For communication with the computer I had, let's say, a very low-level "kind of digital serial communication" where everything had to be controlled step by step. Nothing to do with what would later become serial communication standards, such as RS232-C, which is controlled by high-level commands.

In other words, MEDICID-1 had to be controlled in machine language on practically everything.

With a lot of inventiveness and looking for every last screw, where for example the  "mechanical parts" were all made of plastic. It was possible to "start" this MEDICID-1, and I emphasize that "it was started" because it was necessary to check "by hand" every signal, every control pulse, all communication with the computer, which we also remember that only it has 32 Kilobytes. The only high-level integrated circuits that we had were precisely the analog-digital and digital-analog converters, which we obtained through donations, as well as almost all the rest of the elements.

Only an Engineer, an Electronics Technician, and I, as a Programmer, participated in the construction and start-up of this MEDICID-1.

Let us remember that in 1975 the production of printed circuits is not what it is today so all the equipment was soldered "by hand". Also all startup software was programmed ad-hoc in machine language. These two things made it difficult to start up because we were not sure about anything, but we managed to stabilize everything little by little.

How much we would have given to have an Arduino from now, 2020 !. Young engineers ask me  What am I going to do with only the 64 Kilobytes of the Arduino? And I answer them: You can't imagine what we did with 32 Kb!

Well, in other articles I will refer to the application programming (as it is called now) that this MEDICID-1 had, and I will also refer to the results we obtained with it, from a Ph.D. Thesis to experimental work with cats and monkeys.

Thanks for your attention,

Octavio Báez Hidalgo.