If you're interested, I used a Syntax Highlighter plugin that I found on the web somewhere (the site's URL is now for sale) and added a 6502 highlighter. I forget how it all works together, but if you want to play with it, start here:

http://scottchidester.com/#PluginManager ...

I don't know if you're still on this project, but I've got an SBC that uses a 6850 to talk to a PC at 9600 baud described here:

http://chidesters.org/scott/meadow/Mead ... r_Doc.html

I've seen it done incorrectly in many projects, but they still probably work. This is the correct way:

Thank you, that is an interesting article, and pretty much affirms what I thought was happening (at a basic level at least). I'd suspect that the combination arithmetic/shift instructions are caused by the same phenomenon... that the PLA is generating control signals for the ALU and shift registers ...

That's a little more detail than the original shot I found!

My project is a little old, and very basic (it was just a hobby board), but it interfaces a 6502 with a 6850. You can't beat the 6850 for simplicity, but the 6551 is definitely better.

Here's the link to the project: http://chidesters.org/scott/meadow/Meadow_6502_SBC_User_Doc.html

(P.S. to the ...

I've had success interfacing and programming a 6850 with a 6502. It was very straightforward. I could show you what I did if you're interested.

It's TRON.

-Scott

I have limited experience with the 7805, but I once hooked one up backward. After I inserted it correctly, it output nearly 5V with only the voltmeter loading it, but as soon as I loaded it with anything, the voltage dropped dramatically.

Knee-jerk analysis warning...

I'd assume that it would forget the interrupt--remembering it would require the implementation of a flip-flop in the 6502, and it seems like the 6502 is just as simple as it could possibly be. As you said, interrupt sources typically hold the line low until they've ...

I haven't tried your sort algorithm, I'm only commenting on the O stuff. O(1) I believe would mean that the algorithm takes a fixed amount of time no matter how many elements there are (which, as you might imagine, nobody really talks about because it's silly). O(n) is linear, and O(n^2) is square ...

This BBC handling of error messages seems to agree with the suggestion made earlier that OS calls can be made using the BRK instruction. Apparently the BBC uses an error code following the BRK, which on a different system could just as well be a request for a system service, like using INT 21 in MS ...

I haven't figured out a good or successful way to throttle the CPU to 1/2MHz yet

The best technique is to run, say, 1000 cycles of your simulation, then wait until the next 1ms time.

That sounds obvious, but there are two important things to consider.

First, you should use a blocking function ...

The short answer is yes. You're probably talking about "writing" the chip once by sticking it in an EPROM programmer, or using JTAG. Under normal operation of the system, it is then feasible to not even allow writes to the chip by physically not connecting the write-enable pins.

As for OSes writing ...

Flash memory cells can only be written to on the order of 100,000 or 1,000,000 times before they "burn out." This makes them fine for mass storage, such as one would use a hard disk for, but inadequate for RAM, which needs to handle trillions and quadrillions of writes. Flash is also a little slower ...