Testing DRAM From a Commodore 64

dram

A few months ago, [Josh] was given an old Commodore 64. He needed to make an AV cable and find a new power supply, and even after testing these new parts out, [Josh] found it still wouldn’t boot. Not one to look a gift horse in the mouth — or perhaps he enjoys the challenge — he set out on restoring a thirty year old circuit board.

He replaced a few chips and the caps, but found he had no way to test the DRAM chips. Compared to SRAM or Static RAM used by other computers of the era, DRAM is a bit harder to interface, requiring a capacitor in each memory cell to be refreshed a few dozen times every second. With a bit of help from his good friend [CNLohr], [Josh] figured out a circuit to read and write to his chips and build a small board based on the ATmega8U2 microcontroller for testing purposes.

Hackaday Links: September 1, 2013

hackaday-links-chain

[Anton] has been doing some Commodore 64 Datasette experiments. He managed to connect the C64 audio traces to his smartphone and use it for tape playback.

Not wanting to actually disassemble his Mendel 3D printer, [SteveDC] figured out how to make extenders that increase his build height by about 40%.

We have fond memories of owning an 8088 PC. We did a lot of experimental programming on it but never anything as impressive as getting the TCP/IP stack to run on it. Then again, we’re not sure there was such a thing back when we owned the 10 MHz hardware. That’s right, the microcontrollers we mess around with now days are much faster than that old beast was.

When he goes running at night [Tall-drinks] straps a pico projector to his chest. We guess you’d call the readout a heads-up display… but it’s really more heads-down since it’s projecting on the pavement.

See how things heat up as a Raspberry Pi boots. This video was made using a thermal imaging camera to help diagnose a misbehaving board.

We don’t have very many trinkets on our desk (that would steal space normally reserved for clutter). But be would happily make room for this motorcycle model made from VCR parts (translated).

Making a Commodore 64 portable

making-a-c64-portable

This is [Wpqrek's] Commodore 64 modified to go on the road with him. The elderly machine has a special place in his heart as it was what he learned to code on. He performed a series of hacks which house everything necessary to use the machine inside the original case.

Obviously the hack that has the most effect when it comes to portability was swapping a display for the small LCD mounted above the number keys. This was a pretty simple process because the screen, originally intended for a rear view camera in a vehicle, already had a composite video input. To emulate the floppy disc drive he’s using an SD card via an sd2iec board which he laid out himself. Rounding up the alterations is a stereo SID. The second channel uses the pre-amp circuit cut from a second C64. This audio hardware will let him do cool things like playing some classic Zeppelin.

You can get a video tour of these alterations after the break.

[Read more...]

Playing Led Zeppelin on a C64

In the C64 demoscene there are a ton of awesome software hacks that push the Commodore 64, the 1MHz 6510-based computer from 1982, to its limits. Most of these C64 demos are very much limited by the hardware inside the C64, but the demoscene is always coming up with new ways of pushing the envelope. [No Quarter] just sent in one of these software hacks that propel the capabilities of the C64 into the realm of absurdity by playing full length songs directly from the floppy drive.

Playing a song on the C64 begins with an Amiga and a Perfect Sound digitizer to convert the digital audio file into a 4-bit sample. Once this sample is transferred over to the C64 where it was manually timed so streaming it off a 1581 disk drive would result in the song playing at the correct pitch. It’s an amazing work of optimization; the audio data is streamed off the disk just as fast as it’s played from memory, an amazing data throughput rate for the ‘ol C64

After the break you can see [No Quarter] playing Led Zeppelin, Bon Jovi, Shania Twain, and Extreme. A very, very cool project and with the addition of a C64 hard drive makes it possible to have a media player for the C64.
[Read more...]

A nostalgic look at what a 13 year old can do with a C64

[Armin] recently pulled out his Commodore 64 and looked back on the projects he did as a kid. The surprising thing is that we’re not talking quite as far in the past as you might image. He was 13 in 2002 and the family didn’t have a PC. But more than a decade before his father had purchased a C64 and [Armin] dug into the manual to teach himself how to code. This week he connected the old hardware to his video capture card to give us a demonstration on what he accomplished.

He had seen Windows 95 at the local computer club and figured why not program a clone of the software for the machine at hand? He called it Windows 105 (because that number is higher than 95) and worked out ways to mimic programs like DOS, Corel Draw, Notepad, and some of the programs from Microsoft Office. They didn’t include all the functionality of the real thing, but the look was there.

The story does have a happy ending. [Armin's] parents saw what he was doing and managed to pick up a PC for him to play with. Now he’s a professional programmer looking back on the formative years that got him there. We’ve embedded one of his demo videos after the break for your enjoyment.

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Hardsync – DDR Reimagined for the C64

hardsync

For those of you that like to play dance games, but [DDR] for the [PS2] uses too modern hardware for your tastes, [Hardsync] may be for you. Although the chiptune-style music coming out of the [C64] may not appeal to everyone, one would have to imagine that a game like this could have been a huge hit 30 years ago.

As for the hardware itself, it does indeed use one PS2 element, the dance mat. It’s hooked into one of the C64 joystick ports. In this case, the cable was cut, but it would also be possible to make a non-destructive adapter for it so as not to interfere with any future PS2 fun.

The program is made so that fellow retro-dancers can make their own songs. Each song is a discreet file, and can be reconfigured to your own personal mix. Be sure to check out the video after the break of this old-school dance machine in use after the break! [Read more...]

Dumping a C64 kernel

[Blark] picked up a couple of Commodore 64 machines on Craig’s List so that he could play around with the SID chips inside. But there’s some other fun stuff in there and his attention was drawn to the PROM which stores the kernel. He thought it would be a fun adventure to build a ROM dumper capable of storing binary images.

In the video after the break you can see that when powered up the dumper immediately starts streaming hex values to the terminal. The system is set up to feed a Python script which packs the data stream into an image file. The reading is done by a PIC 18F4520, streaming the data in at 9600 baud with a generous delay between each address read to get the cleanest read possible. He had a bit of help from the AVR Freaks to get to this point.

We’d guess he’s going to pull the image off the chip several times and compare results to filter out any possible data corruption. From there we’re not sure what he’ll do with the files but there’s always the possibility of making is own emulator using this kernel image.

[Read more...]

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