PIC Retrocomputer Boasts VGA, PS/2 Keyboard

You might think that our community would always strive to be at the cutting edge of computing and use only the latest and fastest hardware, except for the steady stream of retrocomputing projects that appear. These minimalist platforms hark back to the first and second generation of accessible microcomputers, often with text displays if they have a display at all, and a simple keyboard interface to a language interpreter.

Often these machines strive to use the hardware of the day, and are covered with 74 logic chips and 8-bit processors in 40-pin dual-in-line packages, but there are projects that implement retrocomputers on more modern hardware. An example is [Sebastian]’s machine based upon a couple of PIC microcontrollers, one of which is an application processor with a PS/2 keyboard interface, and the other of which handles a VGA display interface. The application it runs calculates whether a 4-digit number is a prime and displays its results.

His write-up gives a fascinating overview of the challenges he found in creating a reliable VGA output from such limited hardware, and how he solved them. Though this one-sentence description makes a ton of work sound easy, horizontal sync pulses are generated as hardware PWM, and pixel data is streamed from the SPI bus. The VGA resolution is 640×480, upon which he could initially place a 10×10 block of text. Later optimizations extend it to 14×14.

Sometimes it’s not the power of the hardware but the challenge of making it perform the impossible that provides the attraction in a project, and on this front [Sebastian]’s retrocomputer certainly delivers. We’ve featured many other retrocomputers before here, some of which follow [Sebastian]’s example using modern silicon throughout, while others mix-and-match old and new.

Does This Demo Remind You of Mario Kart? It Should!

Here’s a slick-looking VGA demo written in assembly by [Yianni Kostaris]; it’s VGA output from an otherwise stock ATmega2560 at 16MHz with no external chips involved. If you’re getting some Super Mario Kart vibes from how it looks, there’s a good reason for that. The demo implements a form of the Super Nintendo’s Mode 7 graphics, which allowed for a background to be efficiently texture-mapped, rotated, and scaled for a 3D effect. It was used in racing games (such as Super Mario Kart) but also in many others. A video of the demo is embedded below.

[Yianni] posted the original demo a year earlier, but just recently added detailed technical information on how it was all accomplished. The AVR outputs VGA signals directly, resulting in 100×120 resolution with 256 colors, zipping along at 60 fps. The AVR itself is not modified or overclocked in any way — it runs at an entirely normal 16MHz and spends 93% of its time handling interrupts. Despite sharing details for how this is done, [Yianni] hasn’t released any code, but told us this demo is an offshoot from another project that is still in progress. It’s worth staying tuned because it’s clear [Yianni] knows his stuff.

Continue reading “Does This Demo Remind You of Mario Kart? It Should!”

FPGA Computer Covers A to Z

[F4HDK] calls his new computer A2Z because he built everything from scratch (literally, from A to Z). Well, strictly speaking, he did start with an FPGA, but you have to have some foundation. The core CPU is a 16-bit RISC processor with a 24-bit address bus and a 128-word cache. The computer sports 2 megabytes of RAM, a boot ROM, a VGA port and keyboard, and some other useful I/O. The CPU development uses Verilog.

Software-wise, the computer has a simple operating system, a filesystem, and basic programs like a text editor and an image viewer. Development software includes an assembler and a compiler for a BASIC-like language that resides on the PC. You can also run an emulator to experiment with A2Z without hardware. You can see a “car game” running on A2Z in the video below. You can also see videos of some other applications.

Continue reading “FPGA Computer Covers A to Z”

VGA Monitor Becomes Drawing Toy

We hate to break it to [Rob Cai], but he’s built a VGA drawing toy, not an Etch-a-Sketch. How do we know? Simple, Etch-a-Sketch is a registered trademark. Regardless, his project shows how an Arduino can drive a VGA monitor using the VGAx library. Sure, you can only do four colors with a 120×60 resolution, but on the other hand, it requires almost no hardware other than the Arduino (you do need four resistors).

The hardware includes two pots and with the right firmware, it can also play pong, if you don’t want to give bent your artistic side. You can see videos of both the art toy and the pong game, below.

Continue reading “VGA Monitor Becomes Drawing Toy”

Bitbanging VGA Fits In under 1 kB

Don’t throw those old VGA monitors away, turn them into works of art with [danjovic] and VGA Blinking Lights. This circuit uses a PIC16F688 to generate VGA video. Not just a random spray of monochrome dots either. VGA Blinking Lights puts up an ever-changing display of 48 colored squares.

blink-thumbOriginally created for the square inch contest, VGA Blinking Lights could hide behind a quarter. [Danjovic] dusted his project off and entered it in The 1 kB Challenge. The code is written in PIC assembly. The final hex used to generate the squares clocks in at 471 words. Since the PIC uses a 14 bit word, that’s just over 824 bytes. Plenty of space for feature creep!

Video is generated with a twist on the R2R DAC. [Danjovic] tweaked the resistor values a bit to obtain the correct voltage levels for the VGA standard. The color of the squares themselves are random, generated using a Galois Linear Feedback Shift Register (LFSR).

With only a handful of components, and a BOM cost under $5, this would be a fun evening project for any hardware hacker.

1kb-thumb

If you have a cool project in mind, there is still plenty of time to enter the 1 kB Challenge! Deadline is January 5, so check it out and fire up your assemblers!

Chibiterm Is A Tiny Low-Cost VGA Terminal

A common sight in the days before cheap PCs conquered the world was the dumb terminal. A keyboard and a monitor with a serial port on the back that was usually hooked up to a minicomputer or even a mainframe, these were simple devices. Anything that came into the serial port was rendered on the screen, anything typed on the keyboard was sent out through the serial port. They didn’t need to contain a microprocessor. If you are old enough, you may remember electronics magazines of the 1970s and early 1980s publishing terminal designs based entirely on 74 series logic.

The serial terminal might seem like a redundant historical footnote when viewed from 2016, but they can still find a use among those working with systems such as small embedded microcontrollers that only possess a serial port. To address this application, Hackaday.io user [K.C.Lee] has created a low-cost terminal module for a VGA monitor and a PS/2 keyboard based around an inexpensive STM32F030F4 processor.

Continue reading “Chibiterm Is A Tiny Low-Cost VGA Terminal”

Bootstrapping an Amiga 2000 Graphics Card Because Vintage is Pricey

If you have a computer on your desk today, the chances are that it has an Intel architecture and is in some way a descendant of the IBM PC. It may have an Apple badge on the front, it may run Linux, or Windows, but in hardware terms the overwhelming probability is that it will be part of the Intel monoculture. A couple of decades ago though in the 16- and early 32-bit era you would have found a far greater diversity of architectures. Intel 3-, and 486s in PCs and clones, Macintosh, Commodore, and Atari platforms with the 68000 family, the WDC 65C816 in the Apple IIGS, and the Acorn Archimedes with an early ARM processor to name but a few.

In the tough environment of the 1990s most of these alternative platforms fell by the wayside. Apple survived to be revitalised under a returning Steve Jobs, Atari and Commodore withered under a bewildering succession of takeovers, and Acorn split up and lost its identity with its processor licensing subsidiary going on to power most of the mobile devices we take for granted today.

Surprisingly though some of the 16-bit platforms refused to die when their originators faded from view. In particular Commodore’s Amiga has lived on with new OS versions, new platforms, and community-supported hardware upgrades. News of just such a device came our way this morning, [Lukas Hartmann]’s MNT VA2000, a graphics card for the Amiga 2000 using a GPU implemented on an FPGA.

Continue reading “Bootstrapping an Amiga 2000 Graphics Card Because Vintage is Pricey”