Cheap FPGA boards are readily available, as are VHDL implementations of classic CPUs like the 6502, 6809, and Z80. Up until now, we haven’t seen anyone take these two parts and combine them into a complete system that turns an FPGA board into a complete 8-bit retrocomputer. Thanks to [Grant]’s work, it’s now possible to do just that (server on fire, here’s a google cache) with a $30 FPGA board and a handful of parts.
In its full configuration, the Multicomp, as [Grant] calls his project, includes either a 6502, 6809, Z80, or (in the future) a 6800 CPU. Video options include either monochrome RCA, RGB VGA, or RGB via SCART. This, along an SD card interface, a PS2 keyboard, and the ability to connect an external 128kB RAM chip (64k available) means it’s a piece of cake to build a proper and complete portable retrocomputer.
What’s extremely interesting about [Grant]’s project is the fact the data and address lines are fully exposed on the FPGA board. This means it’s possible to add whatever circuit you’d like to whatever retrocomputer you can imagine; if you want a few NES gamepads, an IDE interface, or you’d like to design your own primitive video card, it’s just a matter of designing a circuit and writing some assembly.
If you’d like to build your own, search “EP2C5T144C8N” on the usual sites, grab a few resistors and connectors, and take a look at [Grant]’s documentation and upcoming examples.
Via 6502.org forums
As a kid, [Boisy] cut his teeth on the TRS-80 Color Computer. It was a wonderful machine for its day, featuring a relatively powerful Motorola 6809 CPU. Although his CoCo was theoretically more powerful than its Commodore and Apple contemporaries, the graphics and sound capabilities of [Boisy]’s first love paled in comparison to his friends 6502-based machines. A little jealously and thirty years go a long way, because now [Boisy] is adding a 6809 microprocessor to the 6502-based machines Atari put out.
[Boisy]’s goal for his Liber809 project was simple: Put a 6809 CPU in an Atari XEGS and get NitrOS-9, the Unix-like OS for the TRS-80 CoCo running on his Frankenputer. After a few months of work, [Boisy] completed his goal and more so: the Liber809 also works on the Atari 1200XL.
To put [Boisy]’s work in perspective, it’s like he took a Macintosh from 1993 and made it run on an Intel 486. While that’s not a terribly accurate analogy, we hope our readers will understand the fortitude needed to make a computer run on a completely different processor.
After the break, you can check out a neat demo app written by [SLOR] from the AtariAge forums showcasing a 6809 running in a machine designed for a 6502. Awesome work for all involved
Continue reading “Giving An Old Atari Computer A Much Needed Upgrade”
[Matt Sarnoff] is designing his own 8-bit computer from scratch. This means not only designing the hardware but also writing his own kernel and custom libraries. Since we last saw this 8-bit machine hes added both video and sound output which has allowed him to start developing some software for his computer (see it play Conways game of life after the break).
Sticking with the retro theme of his computer he uses a TMS9918 chip to output the video and a YM2149 for audio. The YM2149 was the audio chip used in the Atari ST allowing him to play songs generated for that system with a little bit of hacking to account for the fact that the Atari ST ran at 8MHz where his Motorola 6809 only runs at 2MHz.
Via [Retro Thing]
Continue reading “Update: 6809 Computing”