commodore 64

121 Articles

Sad Without A SID? This Comes Pretty Close

July 24, 2018 by 36 Comments

The MOS Technologies 6851, popularly known as the SID, is a legendary sound synthesiser integrated circuit from the early 1980s that is most famous for providing the Commodore 64 home computer with its ability to make noise. At the time it was significantly better than what could be found in competitor machines, making it a popular choice for today’s chiptune and demo scene artists.

There’s a snag for a modern-day SID-jockey though, the chip has been out of production for a quarter century and is thus in short supply. Emulation is a choice, but of little use for owners of original hardware so it’s fortunate that [Petros Kokotis] has produced a SID replacement using a Teensy 3.6.

The operation is simple enough, the Teensy provides all the requisite SID data lines via some level shifters for the host microcomputer, and uses [Frank Boesing]’s ReSID library to do the heavy lifting part of being a SID. You can download the code from a GitHub repository, and he’s posted a video we’ve put below the break showing a prototype in action with a real Commodore 64. The audio quality isn’t brilliant due to a phone camera recording from a very tinny speaker, but notwithstanding that it has the air of the real thing.

This isn’t the first SID we’ve seen here. How about a MIDI synth using one?

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Raspberry Pi Becomes Cycle Exact Commodore Drive Emulator

May 7, 2018 by 83 Comments

The Commodore 1541 disk drive is unlike anything you’ll ever see in modern computer hardware. At launch, the 1541 cost almost as much as the Commodore 64 it was attached to ($400, or about $1040 at today’s value). This drive had a CPU, and had its own built-in operating system. Of course, anyone using a Commodore 64 now doesn’t deal with this drive these days — you can buy an SD2IEC for twenty dollars and load all your C64 games off an SD card. If you’re cheap, there’s always the tape drive interface and a ten dollar Apple Lightning to 3.5mm headphone adapter.

But the SD2IEC isn’t compatible with everything, and hacking something together using the tape drive doesn’t have the panache required of serious Commodoring. What’s really needed is a cycle-accurate emulation of the 1541 disk drive, emulating the 6502 CPU and the two 6522 VIAs in this ancient disk drive. The Raspberry Pi comes to the rescue. [Steve White] created the Pi1541, an emulation of the Commodore 1541 disk drive that runs on the Raspberry Pi 3B.

Pi1541 is a complete emulation of the 6502 and two 6522s found inside the Commodore 1541 disk drive. It runs the same code the disk drive does, and supports all the fast loaders, demos, and copy protected original disk images that can be used with an original drive.

The only hardware required to turn a Raspberry Pi 3 into a 1541 are a few transistors in the form of a bi-directional logic level shifter, and a plug for a six-pin serial port cable. This can easily be constructed out of some Sparkfun, Adafruit, Amazon, or AliExpress parts, although we suspect anyone could whip up a Raspberry Pi hat with the same circuit in under an hour. The binaries necessary to run Pi1541 on the Raspberry Pi are available on [Steve]’s website, and he’ll be releasing the source soon.

This is a great project for the retrocomputing scene, although there is one slight drawback. Pi1541 requires a Raspberry Pi 3, and doesn’t work on the Raspberry Pi Zero. That would be an amazing bit of software, as ten dollars in parts could serve as a complete emulation of a Commodore disk drive. That said, you’re still likely to be under $50 in parts and you’re not going to find a better drive emulator around.

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Emulating A Complete Commodore 64

March 28, 2018 by 40 Comments

When the Commodore 64 was released in 1982, it was a masterpiece of engineering. It had capabilities far outstripping other home computers, and that was all due to two fancy chips inside the C64. The VIC-II, the video chip for the C64, had sprites and scrolling, all stuffed into a single bit of silicon. The SID chip was a complete synthesizer on a chip. These bits of silicon made the C64 the best selling computer of all time, but have also stymied efforts to emulate a complete C64 system on a microcontroller.

[Frank Bösing] has just managed to emulate an entire C64 on a Teensy 3.6. The Teensy uses an exceptionally powerful microcontroller, but this is a labor of love and code.

The inspiration for this project comes from a reverse-engineered SID chip that was ported to the Teensy 3.2. The SID chip is the make it or break it feature of any C64 emulation, but the Teensy 3.2 didn’t have enough RAM for the most recent versions of reSID. With the release of the Teensy 3.6, [Frank] figured the increased amount of RAM would allow a complete C64 system, so he built it.

The new C64 emulator uses a Teensy 3.6, with a small add-on ‘shield’ (or whetever we’re calling them) to provide connectors for joysticks and the Commodore IEC bus. There’s audio out, support for USB keyboards, and support for an IL9341 SPI display or a regular ‘ol VGA display.

The entire development of this Commodore emulator has been documented over on the PJRC forums, and all the code is over on GitHub. It’s a fantastic piece of work, and as the video (below) shows, this is a real Commodore 64 that fits in your pocket.

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Can This Commodore 64 Be Saved?

December 21, 2017 by 29 Comments

If you are a certain age, there’s a fair chance your first computer was a Commodore 64. These machines are antiques now, and [RetroManCave] received one from a friend’s loft in unknown condition. He’s made two out of three videos covering the machine, its history, and its internals. Assisting is Commodore 64 expert [Jan Beta] who apparently owned one way back when. You can see the first two videos, below.

The machine isn’t as old as you might think — it is the “newer” case style (circa 1987). [Jan] gives a great overview of the different motherboards you might encounter if you are lucky enough to come across one of these in a dumpster somewhere.

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RetroModem For The Commodore 64

October 7, 2017 by 17 Comments

Retrocomputers are fun, but ultimately limited in capability compared to modern hardware. One popular pursuit to rectify this is the connection of early home computers to the Internet. To that end, [que] built the Retromodem for the Commodore 64.

The build starts with a case from an Intel 14.4 modem. A little fast for the Commodore 64 era, but anachronism is charming when done tastefully. Inside is an Arduino with an ethernet module to handle the heavy lifting of carrying packets to the outside world.  [que] took the time to wire up status LEDs for the proper vintage look, which really adds something to the project. They switch on and off to indicate the various settings on the modem – it’s great to see in the video below the break the “HS” LED light up when the baud rate is changed to a higher speed.

The project implements most of the Hayes command set, so you can interface with it over a serial terminal just like it’s 1983. [que] doesn’t go into too many details of how it’s all put together, but for the experienced code warrior it’s a project that could be whipped up in a weekend or two. For a more modern take, perhaps you’d like to hook your C64 up over Wifi instead?

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Hacked Headset Brings VR To The Commodore 64

September 14, 2017 by 6 Comments

The venerable Commodore 64 got a lot of people started in computers, and a hard core of aficionados keeps the platform very much alive to this day. But a C64 just doesn’t have the horsepower to do anything more than some retro 8-bit graphics games, right?

Not if [jim_64] has anything to say about it. He’s created a pair of virtual-reality goggles for the C64, and the results are pretty neat. Calling them VR is a bit of a stretch, since that would imply the headset is capable of sensing the wearer’s movements, which it’s not. With just a small LCD screen tucked into the slot normally occupied by a smartphone in the cheap VR goggles [jim64] used as a foundation for his build, this is really more of a 3D wearable display — so far. The display brings 3D-graphics to the C64, at least for the “Street Defender” game that [jim64] authored, a demo of which can be seen below. We’ll bet position sensing could be built into the goggles to control the game too. Even then it won’t be quite the immersive (and oft-times nauseating) experience that VR has become, but for a 35-year old platform, it’s not too shabby.

Looking for more C64 love? We’ve got a million of ’em — case mods, C64 laptops, tablets, even CPU upgrades.

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Fixing Bugs In Ancient BASIC Games

July 5, 2017 by 39 Comments

Before everyone learned programming on Stack Exchange, things were much different. Computer magazines had BASIC programs in them, which readers would type out, line by line, and hit RUN. In theory, this is a terrible way to learn programming; it’s simply rote recitation without any insight into what the code is actually doing. Of course, copying and pasting from Stack Exchange is exactly the same thing, so maybe these magazines were ahead of the curve.

[0xA000] recently came across one of his old computer magazines containing the type-in listing for Blindganger, a game where you wander a maze blindly. When [0xA000] typed this game into his C64 back in 1988, the game didn’t work. Thirty years later, he decided to give it another go and ended up fixing bugs in an old computer game.

When [0xA000] typed this game into his computer back in 1988, the map just didn’t work, and the final screen revealed a maze where the walls were where they shouldn’t be. A quick Google turned up a disk image of the same game that had the same problem. This bug was obviously in the section of code that draws the map at the end of the game, so [0xA000] started looking there. The offending typo in the code was an $F4 instead of an $F5, or 244 instead of 255. This shifted the colors of the map by 11 positions, meaning the locations marked as visited in the final screen were wrong. Whether this bug cropped up in development or was just a simple typo when typesetting the magazine doesn’t really matter now; after 29 years, this bug is fixed.