The Commodore 64 (C64) holds a particular place within the historical past of non-public computing. Launched in 1982 by Commodore Worldwide, it rapidly turned an iconic machine and an emblem of the house laptop revolution. The recognition of the Commodore 64 was unparalleled, and even to at the present time, it stays the best-selling laptop mannequin of all time. Its affordability, versatility, and intensive software program library made it a beloved alternative for each gaming and productiveness.
Throughout its prime, the Commodore 64 was a game-changer on the earth of computing. Priced competitively at $595, it was accessible to a variety of shoppers. Its superior graphics and sound capabilities, particularly for its time, made it a dominant pressure within the gaming trade. Numerous classics, akin to “Maniac Mansion,” “Pitfall,” and “Summer season Video games,” had been developed for the C64, charming a whole era of avid gamers.
At the moment, the Commodore 64 continues to be cherished by a devoted group of lovers and collectors. Its legacy lives on via varied emulators, {hardware} remakes, and preservation efforts. The retro computing scene thrives with people who tinker, modify, and develop new software program and {hardware} for the C64. A variety of on-line communities nonetheless present platforms for sharing data, discussing initiatives, and reliving the nostalgia related to this iconic machine.
The enlargement port can be utilized for cartridges (📷: Linus Åkesson)
Linus Ã…kesson is most positively counted among the many modern-day followers of the Commodore 64. In reality, he loves this traditional laptop a lot that he spent over three years constructing what he calls the Commodordion — a playable accordion constructed from a pair of Commodore computer systems and a stack of floppy disks. If that isn’t love, we don’t know what’s!
Whereas the Commodordion is magnificent, even when not particularly helpful, it does have one notable disadvantage. The software program that powers the pc is loaded from a cassette tape drive emulator. It really works, positive, however it’s gradual and entails some guide steps to get it up and operating, to not point out that cassette tape-based storage is notoriously unreliable.
Due to his familiarity with the pc, Ã…kesson knew {that a} customized cartridge would resolve the issue. They’re quick, dependable, and don’t require any guide steps in addition. However to interface with the enlargement port, a customized PCB is required. Positive, it’s cheap to have a customized PCB produced as of late, nevertheless it usually takes a number of weeks to get one in your palms. So Ã…kesson thought-about extra DIY-friendly choices he might construct with elements he already had readily available.
A stripboard appeared like a pure possibility, and the 0.1″ spacing between pads even matched up with the pinout of the Commodore’s enlargement port. However there was one large drawback with this concept — the stripboard solely has contacts on one facet, however the enlargement port has contacts on either side. Undeterred, Ã…kesson studied the pinout of the enlargement port, and realized that he may be capable of get by utilizing solely the pins on the highest facet of the connector.
The finished customized cartridge (📷: Linus Åkesson)
At first look, this would appear not possible as a result of the handle pins are on the underside portion of the connector. How can the pc ask for information from particular reminiscence addresses with out specifying the handle, in any case? Ã…kesson realized that, as long as information is being accessed sequentially, you don’t want to know every handle. You possibly can merely current one byte after the opposite on the information bus as they’re requested. However how have you learnt when they’re being requested? Straightforward sufficient, simply watch the chip choose line for the ROM chip — when it goes low, put the subsequent byte on the bus.
Within the spirit of working with what he had readily available, an ATmega88 microcontroller was utilized to service the pc’s requests, along with a tristate buffer to take away it from the information bus when information was not being requested. This microcontroller has 8 KB of flash reminiscence, which is enough for the Commodordion’s wants anyway, however it’s not quite a bit, even for a Eighties laptop. So, the accessible reminiscence had for use properly, with this system being tightly packed in.
The answer for this drawback was to incorporate a small bootloader that writes itself to the pc’s RAM. This bootloader then sequentially grabs program information from the customized cartridge to load into system reminiscence. Utilizing this DIY cartridge, the Commodordion can boot up immediately after powering up.
Ã…kesson has produced a really detailed write-up with step-by-step directions for anybody that wish to reproduce the work. If you’re not serious about accordions, how a few theremin? Or perhaps you wish to do some machine studying together with your Commodore?
