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.

The Impressive Z80 Computer With The Unfortunate Name

We’ve seen a lot of retro builds around the Z80. Not many are as neatly done or as well-documented as [dekeNukem’s] FAP80 project. Before you rush to the comments to make the obvious joke, we’ll tell you that everyone has already made up their own variation of the same joke. We’ll also tell you the name is a cross between an old design from [Steve Ciarcia] called the ZAP80 and a reference to the FPGA used in this device.

[dekeNukem] says his goal was to create a Z80 computer without all the baggage of using period-correct support chips. You can argue about the relative merits of that approach versus a more purist build, but the FAP80 has a 5 slot backplane, VGA output, a PS/2 keyboard port and more. You can see one of many videos showing the machine below.

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Retrocomputing for $4 with a Z80

Sure, you’d like to get in on all the retrocomputing action you read about on Hackaday. But that takes a lot of money to buy vintage hardware, right? Sure, you can build your own, but who has time for a big major project? [Just4Fun] has a Hackaday.io project that disproves those two myths and gives you no more excuses. His retrocomputer? A 4MHz Z80 that can run BASIC with 64K of RAM, all built on a breadboard with 4 ICs. The cost? About $4.

Of course, that’s with some power shopping on eBay and assuming you have the usual stuff like breadboards, wire, small components, and a power supply. While it will gall the anti-Arduino crowd, [Just4Fun] uses an Arduino (well, an ATmega32A with the Arduino bootloader) to stand in for a host of Z80 peripheral devices. You can see a video of the device below, and there are more on the Hackaday.io project page.

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Mark 8 2016 Style

In the mid-1970’s there were several U.S.-based hobby electronics magazines, including Popular Electronics and Radio Electronics. Most people know that in 1975, Popular Electronics ran articles about the Altair 8800 and launched the personal computer industry. But they weren’t the first. That honor goes to Radio Electronics, that ran articles about the Mark 8 — based on the Intel 8008 — in 1974. There are a few reasons, the Altair did better in the marketplace. The Mark 8 wasn’t actually a kit. You could buy the PC boards, but you had to get the rest of the parts yourself. You also had to buy the plans. There wasn’t enough information in the articles to duplicate the build and — according to people who tried, maybe not enough information even in the plans.

[Henk Verbeek] wanted his own Mark 8 so he set about building one. Of course, coming up with an 8008 and some of the other chips these days is quite a challenge (and not cheap). He developed his own PCBs (and has some extra if anyone is looking to duplicate his accomplishment). There’s also a video, you can watch below.

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By the Glow of the CRT

If you are a certain age, you probably remember writing software (or playing Adventure) bathed in an amber or green light from an old CRT terminal. If you are even older, you might have found it way better than punching cards, but that’s another story. [Tobi] wanted to relive those days (well, sounds like he is too young to have lived them to start with) so he hooked up a VT220 terminal to his Linux box.

This isn’t that surprising. Linux’s forefather, Unix, expected these kind of terminals (or a hard copy TeleType) and all the trappings for working with a glass terminal are still in there. You do have to deal with a few configuration items that [Tobi] works through.

In fact, it appears that he wrote his blog post using vi on that very VT220 using a text-based Web browser to research the links. He has a lot of resources for connecting a terminal of any sort (or even a terminal emulator) to a Linux computer.

There’s been a lot of interest in old terminals lately. You see a lot of old VT100s lying around. I personally have an ADDS Regent 100 that occasionally connects to several of my computers. You can see it in the video below.

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Hackaday Links: October 30, 2016

Diablo. Mech Warrior. Every LucasArts game. There are reasons to build an old PC, and no, emulation cannot completely capture the experience of playing these old games. [Drygol] set out to create a retro PC and succeeded brilliantly. The built features an old desktop AT case (when is the last time you saw one of them?), a 233MHz Pentium with MMX technology, an ancient PCI video card, and an old ISA Ethernet card (with AUI connector). Incoming upgrades will be an ATI 3D Rage PRO, PCI SoundBlaster, and hopefully Windows 98SE.

Right now, we’re gearing up for the Hackaday Superconference next weekend. It’s going to be awesome, and we’re going to announce the winner of the Hackaday Prize. We have another contest going on right now – the Enlightened Raspberry Pi Contest. The name of the game here is documentation. Build something, document it on hackaday.io, and you get some cool prizes.

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Raspberry Pi Boots CP/M

Retrocomputing is an enjoyable and educational pursuit and — of course — there are a variety of emulators that can let you use and program a slew of old computers. However, there’s something attractive about avoiding booting a modern operating system and then emulating an older system on top of it. Part of it is just aesthetics, and of course the real retrocomputing happens on retro hardware. However, as a practical matter, retrocomptuters break, and with emulation, you’d assume that CPU cycles spent on the host operating system (and other programs running in the background) will take away from the target retrocomputer.

If you want to try booting a “bare metal” Z80 emulator with CP/M on a Raspberry Pi, you can try EMUZ80 RPI. The files reside on an SD card and the Pi directly boots it, avoiding any Linux OS (like Raspian). It’s available for the Raspberry Pi Model B, A+, and the Raspberry Pi 2 Model B. Unlike the significant boot times of the standard Linux distros on the earliest models of Pi, you can boot into CP/M in just five seconds. Just like the old days.

The secret to this development is an open source system known as Ultibo, a framework based on Open Pascal which allows you to create bare metal applications for the Raspberry Pi. The choice of Free Pascal will delight some and annoy others, depending on your predilections. Ultibo is still very much in active development, but the most common functions are already there; you can write to the framebuffer, read USB keyboards, and write to a serial port. That’s all you really need to make your own emulator or write your own Doom clone. You can see a video about Ultibo (the first of a series) below.

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