[Jeff] says that designing your own 6502 computer is a rite of passage, and he wanted the experience. His board can accept a real 6502 or the newer CMOS variant that is still available. There are a few modern conveniences such as USB power and provisions for using a USB serial port.
We are spoiled today with microcontrollers having everything in one package, but with this class of CPU you need your own memory, I/O devices, and other support chips. [Jeff] took a traditional approach, but picked components that are still easy to obtain. Some designs now push all the support functions to a more modern processor like an Arduino, which is very simple to do, but doesn’t feel as authentic, somehow.
For software, there are several versions of BASIC, one based on Ohio Scientific’s variant. There’s also a monitor image. With 32K of RAM, this would have been a respectable machine in its day. The BASIC interpreter dates from 1977. There are plenty of old BASIC games from those days and [Jeff] shows a famous version of poker running on the board. The 6502’s assembly language isn’t that bad, either.
We love these old retro builds. If you don’t fancy all the support chips you can, as we mentioned, use another processor. Or, try an FPGA.
9 thoughts on “Everything Old Is New Again: Another 6502 Board Is Born”
Could we get a quick rundown of the specs, w/o having to Wade through a video, please? 32K RAM is all that was divulged there.
Here, hold my coffee..
2MHz max clock (1.832 on board)
32K static RAM
16K ROM via 27128 UV erasable
Serial via a 6850 through an external FTDI-USB
6522 VIA broken out to header
No native video generation
It’s missing the obligatory DIN41612 connector ;)
6502/65C02 can be a lot of fun. The instruction set is very RISC-like in many ways being a single-address architecture. They could be a lot more fun at 16 or 20 MHz and with no-wait static RAM.
What is available these days for fast 6502? Accelerators in the 1980’s topped out at 10MHz IIRC and the Western Design has a 65C02 at 14MHz possibly doing 18 or 20MHz (https://www.westerndesigncenter.com/wdc/w65c02s-chip.php). Maybe some gate array implementations that are faster?
Here you have the ~73MHz FPGA 65C02 implementation: https://github.com/MorrisMA/MAM65C02-Processor-Core. Anyway working Commodore 65, MEGA65 is under development on https://mega65.org with, I believe, it has 40MHz 65C02 implementation. Few 6502 cores you can find on the webpage: https://opencores.org.
Good info. The 73MHz is the microcode rate so 65C02 instructions are equal to an “18MHz 6502”.
There’s nothing I like seeing more than another 6502 board, let alone one that runs both the original chips or CMOS!
It’s also a pleasure to read the words “Ohio Scientific” these days, top hackaday article 10/10.
(This is the part where I end up re-reading all the other articles tagged 6502 here, or spend the rest of the day tinkering with my own boards…)
Ohio Sci. Most affordable and expandable backplane ever. 18 slots on this one https://hosting.photobucket.com/albums/i382/Comedicles/BitsnPieces/LandOfLostProjects/OSI_zpsbz9wbuvz.jpg
Where can we buy this product and it accessories?
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