Emulating A Complete Commodore 64

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?

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

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

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

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.

Adding Character To The C64

The venerable Commodore 64, is there anything it can’t do? Like many 1980s computer platforms, direct access to memory and peripherals makes hacking easy and fun. In particular, you’ll find serial & parallel ports are ripe for experimentation, but the Commodore has its expansion/cartridge port, too, and [Frank Buss] decided to hook it up to a two-line character LCD.

Using the expansion port for this duty is a little unconventional. Unlike the parallel port, the expansion port doesn’t have a stable output, as such. The port contains the data lines of the 6510 CPU and thus updates whenever RAM is read or written to, rather then updating in a controlled fashion like a parallel port does. However, [Frank] found a way around this – the IO1 and IO2 lines go low when certain areas of memory are written to. By combining these with latch circuitry, it’s possible to gain up to 16 parallel output lines – more than enough to drive a simple HD44780 display! It’s a testament to the flexibility of 74-series logic.
It’s all built on a C64 cartridge proto-board of [Frank]’s own design, and effort was made to ensure the LCD works with BASIC for easy experimentation. It’s a tidy mod that could easily be built into a nice enclosure and perhaps used as the basis for an 8-bit automation project. Someone’s gotta top that Amiga 2000 running the school district HVAC, after all!

Building a Replica Final Cartridge III

The Commodore 64 was the computer of the 8-bit era, and remains the highest selling computer of all time. In addition to disk and tape drives, it also had a cartridge interface. A popular extension cartridge was the Final Cartridge III, which offered a variety of disk utilities and a GUI. [Greisi] was in possession of a no longer functional cartridge, and decided to reverse engineer the device.

[Greisi] started by desoldering all the ICs and mapping out a schematic for the board. The design centers around common parts for the era, such as a UV-erasable EPROM and some 74-series logic. [Greisi] decided to then modernise the design and make some improvements. Adding a fuse should avoid the cartridge catching on fire, and a bunch of decoupling capacitors on all the ICs should reduce noise. A FLASH chip is used instead of the old school UV-erasable part, which makes writing to the device much easier.

It’s a great build performed in a stunningly tidy workshop, and [Greisi] has provided the schematics and PCB designs to the public here. That means that many more users can build their own Final Cartridge III without having to hunt for original hardware which is growing scarcer. You can learn more about the Final Cartridge III on Wikipedia.

We’ve actually seen the Final Cartridge III before – used in this blinkenwall installation. Video below the break.

[Thanks Adrian!]

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