Gabriel Caffarena

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Jun 06 2019

A telegram about the datagram: Short history of OSI

Short history of OSI This post is based on the article  “The Internet that wasn’t” by  Andrew L. Russell [Russell13] published in IEEE Spectrum in 2013. The author is Assistant Professor of History at the Stevens Institute of Technology, N.J., USA and he wrote a prior article in 2006 about OSI history [Russell06] and felt …

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Apr 30 2019

About timing diagrams of Moore finite state machines

About timing diagrams of Moore finite state machines Finite state machines (FSMs) in the context of digital electronics are circuits able to generate a sequence of signals (i.e. outputs) that react according to the current state of the system and the values of input signals. The goal of this post is to explain how to …

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Mar 30 2019

Fast binary conversion – Part II

[Fast binary conversion – part I] In this post we continue talking about fast binary conversion, this time focusing on signed numbers, in particular two’s complement (2C) numbers .  We introduced binary in a previous post (Sinistar), and two’s complement was only briefly tackled: ” In 2C’s representation, the most significant bit (the one most …

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Feb 24 2019

Fast binary conversion – Part I

Binary is the basis of digital systems and it is important to be fluent when it comes to obtain the decimal value of a binary number. In this post we will start dealing with fast binary to decimal conversion for numbers up to 16 bits. This will be handy if you work in the domain …

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Feb 01 2019

Torres Quevedo and the first computer

(originally published in Spanish in November 2018) I am in the middle of intensive reading up on the inventions of Leonardo Torres Quevedo, and, even though is a bit early, I would like to share my findings, especially those related with the world of computing. Additionally, I am Spanish and I talk all the time …

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Nov 06 2018

Sinistar: the arcade of the eternal youth

There is nothing like finding an arguably fun example to support any of the arid concepts populating the fields of digital electronics, computing and signal processing. Some time ago, I came across a fantastic video published by the IEEE Spectrum Magazine (Five Infamous Arcade-Game Glitches), devoted to programming mistakes (i.e. glitches) in arcade videogames: Asteroids …

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Oct 08 2018

Total recall: “6502: igniting the digital revolution” (2017)

The 6502 was pure magic out of transistors. The creators of this microchip are truly digital heroes that achieved the unthinkable: creating a low-cost microprocessor in 1975 that shaped the electronic industry. This device was used in legendary machines, such as Atari VCS 2600, Apple II, Commodore 64, Nintendo Famicon, etc. An animated GIF is …

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Sep 05 2018

(RetroMadrid2018) 4- and 8-bit pioneers: the creation of the microprocessor [the talk I couldn’t give]

(Also available in Spanish. Use the language switch) Please find a video (in Spanish) of a talk I planned to give in RetroMadrid 2018 (a Spanish event for retrocumputing), but that eventually I got sick and I could not attend. The talk covers the following points: Review of my previous talk (history of 6502) in …

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