Hello 6502!

The first time that I got my "Propeddle" to run.

The Propeddle is a Software-Defined Computer, originally intended to be a Commodore PET/CBM replica, but it will be possible to re-create many other 6502-based systems too. It uses a Parallax Propeller and a 6502 processor, and the schematic was based on Dennis Ferron's 6502 laptop. The name is a contraction of "Propeller" and "Peddle" after Chuck Peddle, the head designer of the 6502. This is my first Propeller project and I've gotten this far in about 2 weeks, working a couple of hours every evening.

What you're seeing is an early version of the schematic (largely identical to Dennis Ferron's project) running a modified version of the VGA_Hires_Txt driver on the Propeller. That driver serves as a memory-mapped monochrome (1 bit) text screen at 40x25 characters with a PETSCII font, which is mapped into the 6502's memory space. The top of the screen is Dennis' 6502 debugger demo program. The listing on the left is meaningless in this demo, but the listing on the right is the program that's running on the 6502: NOP / INC $6380 / JMP $FC00. Location $6380 is a memory location on the screen (it's mapped at $6000 for now), so you see the character at that location changing because of the code running on the 6502.

The LED on the breadboard is controlled by the propeller and blinks each time the 6502 fetches an instruction from memory (SYNC output). This happens about 30 times per second because I have the 6502 running at about 100Hz for this test.

My 6502 was borrowed from a MicroKim. The 32K SRAM chip was borrowed from a memory expansion board of the MicroKim, and the Propeller (although breadboarded now) is still part of a Pocketerm. All these can be purchased online as kit from Briel Computers. Thank Vince!

I will have to make some optimizations to Dennis' software: The "Run6502" module is well written and works great for the general case but doesn't allow running the 6502 at normal speed: Reading the address bus (8 bits at a time), reading and writing the data bus, deciding whether to feed the 6502 fake NOPs for data transfers, enabling and disabling the RAM control lines and generating clock pulses is just too much to do for one cog in 1 microsecond.

I've made quite a few changes to the project since I made this video. Check out the links below for more information. Eventually, I want to make the hardware available as a kit.

Home page: http://www.propeddle.com
More information: http://www.savagecircuits.com/forums/showthread.php?677
Follow me on Twitter at http://www.twitter.com/jacgoudsmit

Category:

Science & Technology

Tags:

• 6502
• Commodore
• PET-2001
• CBM 4032
• Propeddle
• Parallax Propeller
• MicroKim
• Pocketerm
• Briel Computers
• Dennis Ferron
• Prop-6502

[xadam2dudex]

u shoulda just bought an old c-64

[jacgoudsmit]

@xadam2dudex Anyone with $30 and an eBay account can do that. That's no fun at all :-)

[w1k]

hmmm, i dont know if this is a good idea..

[xadam2dudex]

@jacgoudsmit u spent a bunch of money just to make a hello world program

[29riteshkakkar]

nice work.............

[joecassara]

Great work!