If you’ve at any time used a house laptop or computer from the late 1970s or early 1980s, you’ll no question be common with the gradual speed of their user interfaces. Even listing the contents of a Standard software from RAM could just take many seconds, with the display updating just one line at a time. Video video games have been absolutely optimized for velocity, but could nevertheless deal with just a couple of slowly-shifting objects at the very same time. Plainly, participating in anything resembling comprehensive-motion movie on hardware from that period would be definitely not possible – or so you may possibly believe.
In simple fact, [Thorbjörn Jemander] has managed to persuade a Commodore PET to play YouTube films at a wholly realistic 30 frames for every second. He describes the course of action of building the “BlixTerm” components and program in his online video (embedded underneath), alongside with heaps of useful data on how to press digital units to their complete restrictions.
Obviously, the PET desires a little bit of aid from modern day hardware, in this scenario a Raspberry Pi Zero 2 W hooked up to the “User” expansion port. The Pi connects to YouTube by way of WiFi and hundreds the requested video, then downconverts it to a 640×200 grayscale stream and transforms each and every frame to an 80×25 grid of figures, making use of people from the PET’s ROM that most closely resemble the pattern wanted.
While it took pretty some energy to squeeze more than enough overall performance out of the Pi to do all of this in true time, the trickiest bit was acquiring the ensuing character stream into the PET’s movie memory quick ample. To do this, [Thorbjörn] intended a unique interface card with 2 KB of twin-port SRAM, which enabled the Pi to retailer its online video frames as before long as they have been all set on one facet, and the PET to load them at its personal speed from the other facet. With just sixteen microseconds out there to process each and every byte, the PET’s CPU can execute only 4 or 5 machine code guidance scarcely sufficient to load and retailer a solitary character and bounce to the next memory tackle.
The close result, as you can see in the video, is actually amazing. Even within the constraints of the Commodore character set, the ensuing graphic is obviously recognizable, when the frame charge appears to be to defy the hardware’s restrictions.
If you are a Commodore aficionado and wanting to know what the hell that unusual PET 600 product is all about, [Thorbjörn] made a online video about that as well it’s a rebadged 8296 aimed at the Swedish marketplace. We’ve in fact viewed a project to create are living movie on the PET ahead of, while at a a lot reduced body fee. Many thanks for the idea, [Keith Olson]!