Commodore 64 Mods Make A Mobile Computer

Some Commodore C64 owners and enthusiasts keep tinkering with their precious units, adding upgrades all the time. [wpqrek]’s latest upgrade to his C64 makes it totally portable – he added DC-DC converters to allow it to run off external battery sources.

He installed two separate DC-DC converters – one for 5V and another for 9V inside the enclosure. He opted for these high-efficiency converters because he planned to use batteries to power the device and wanted to maximize the juice he was extracting. He wired up a barrel jack socket to accept a 12V input, and another XT60 socket where he could attach a LiPo battery. A common 2200mAh RC battery is enough to power his C64 for 1.5 hours. To ensure the LiPo battery doesn’t get fully discharged, he’s added a simple buzzer circuit that starts beeping at around 3.3V.

How does just adding an external battery help make it portable? Well, he’s already added a small LCD display and a couple of other mods, that we featured in an earlier post. These earlier mod’s didn’t make the unit truly portable. Adding the latest hack does. Check out the video after the break.

16 thoughts on “Commodore 64 Mods Make A Mobile Computer

    1. Yea but this is about 12 lbs. lighter than the SX-64, has more storage (I saw an SD on the side of this one) and better speakers! Still if someone has an SX-64 laying around it would be a sweet hack.

  1. Sorry it looks a complete mess. Bad mod. Computer looks crap with that speaker hanging out of it. Could do a much better job if you tiny it up inside. You could of used laptop subwoofer and speakers and hide them inside. Sorry one ungly computer. Why don’t you just make a handheld c64? Would be a lot easier.

    1. The 9VAC RMS from the power brick was rectified to supply 12V/9V DC to the 6581/8580 SID chip. The AC was also used to provide the 50/60 Hz ticks for the Time Of Day clock (PAL/NTSC) – they didn’t use a VIC interrupt for the TOD tick because the crystal oscillator used for the various clock signals wasn’t as stable as the mains.

    2. You are correct. The 9 volt AC is used to supply power via a charge pump to the SID sound generator chip, provide 6.8V via a rectifier to the cassette motor, a “0” pulse for every positive half wave to the time-of-day (TOD) input on the CIA chips, and 9 volts AC directly to the user-port. Thus, as a minimum, a 12 V square wave is required. But a 9 V sine wave is preferred. (stolen from Wikipedia, because I couldn’t remember exactly).

      This means no TOD clock, and no paddles. A simple 555 circuit would be able to convert the DC to AC of course.

  2. Hi, I must say aesthetically not that great but the battery operated part of your mod is very interesting .
    Can you share more details (been on you site, I found nothing more than few photos and superficial descriptions) that will make other people capable to replicate the battery operated feature?

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