Well, I must confess: I love programmable calculators, although I have no such machine. I was too young and those things were so expensive here, in the former Eastern Bloc. But some people had them, primarily the well-known TI machines, like TI-57, TI-58, etc. I read a lot of articles with great titles, like the "Lunar landing for a TI-57", I have dreamed about being Neil Armstrong with a pocket calculator, but there were a lot of SBR, STO, RCL, and GTOs in those listings... You know it: The majority of all retro feelings is the strange smell of those old times, spent in a basement, reading m ..read more

Okay, I have no new project now, so I decided to publish some of my saved pages as tips for you. C compiler for 6809 Pierre Sarrazin made a cross compiler for C language, called CMOC. It runs under Linux or Cygwin and is published under the GPL3 license. It has limited features (no stdlib, limited floats, etc.) The primary target is the CoCo, but you can compile programs for Dragon, Thomson, Vectrex, or OS-9 and FLEX operating systems. Space Invaders Cardbox Rob Cai found some old intercoms with a CRT mini display, so he decided to make a mini Space Invaders arcade machine. Just take that dis ..read more

One of the biggest challenges for retro computer makers is the terminal. You know, that part with a keyboard and a display. Building an SBC is easy: you use the 7segment display and 20-25 push buttons in a matrix, and everything is OK. But what about more sophisticated machines, with text output, or graphics, with a full QWERTY keyboard...? You can use, of course, a PS/2 PC keyboard, but it hasn't an authentic retro feeling. On the other hand, PC keyboards are deadly cheap. You can still make a membrane keyboard as the ZX-80 has, it's cheap enough, but... you know... You can cannibalize old c ..read more

or should I say: "my to-read list"? There are a lot of projects around. They bring a lot of inspiration, thoughts, and ideas, ... For example, this one, named PERSEUS-9: PERSEUS-9 (photo by Hackaday.io) It is a two-board computer, based on a 6502 CPU, and to be honest, the computer itself is a simple basic 6502 computer, combined with a 6502-based terminal. But I really do love the design. I love that aluminum case, that keyboard, and of course: that display! Yes, it takes 35 pieces of HCMS-2912 LED matrix displays. 33USD each. It means the display costs more than a thousand bucks. Awwwww. Bu ..read more

I have to confess: I had a lot of fun with ESP8266 modules. It's a perfect replacement when you need an Arduino with connection. Later, when ESP32 came, I plan to use those modules, but I had no time, because of work, etc. Now I have time, I have energy, so let's play. And the best way to start playing with an electronic module is to make something totally obsolete, like, umm... Yes, like a retro computer! So I started googling "ESP Spectrum", and voila! There were some results. And one of the most interesting projects navigates me to the ESP32 VGA kit. Or, to be honest, ESP32 + VGA + keyboar ..read more

Bryan Sparks, President of DRDOS, clarified the license of CP/M: Let this paragraph represent a right to use, distribute, modify, enhance, and otherwise make available in a nonexclusive manner CP/M and its derivatives. This right comes from the company, DRDOS, Inc.'s purchase of Digital Research, the company and all assets, dating back to the mid-1990’s. DRDOS, Inc. and I, Bryan Sparks, President of DRDOS, Inc. as its representative, is the owner of CP/M and the successor in interest of Digital Research assets. Of course, it was "opened" a long time before, but with an unclear clause, mention ..read more

What else to start with but the physical wiring of the 6809… Perhaps unsurprisingly, there is some similarity to the 6502 processor. This is logical because, as we've said several times, both the 6502 and 6809 are based ideologically on the same predecessor, the 6800. Pin description The processor has both main buses, the data bus (D0 - D7) and the address bus (A0 - A15). There are no surprises here. The signals are not multiplexed and are fully available. The /RESET input is used to initialize the processor to its default state. The input is a Schmitt flip-flop circuit, so a simple circuit ..read more

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Who doesn't know one-bit music! Well, actually, um, all the Atari and Commodore players whose computers had multi-channel sound generators. It was us on the Spectrum who had to make do with a single wire, where it was either 0 or 1, and depending on how fast you fiddled with it (programmatically), that's the sound it made… Of course, it wasn't particularly glorious, but it worked, and when you gave it a little bit, the results were really interesting. How could you give it? A little theory to start with… Yeah, it's necessary! Sound, as it is known, is a wave transmitted through the air or oth ..read more