6502.org

Quick question about this, is it safe to turn the machine on to verify it works without any kind of clock generation for phi2? The emulation mode light should turn on at least verifying the CPU has some functionality, and that's what I'd like to do, but I haven't for fear of problems with that. I know the 65c816 is fully static, so there *shouldn't* be any issues, but I'd just like to confirm before I blow something up.

Is it even worth doing? With no Phi2 applied, the amount of functionality you can verify will be small to nil. Are there other goals, or do you simply wish to observe the state of the E (Emulation Mode) output pin? Anyway, no, you won't blow anything up. Just be sure (as always) to avoid any case where the input of a MOS or CMOS chip isn't pulled to a valid logic level, either high or low. In your test it sounds as if certain clock inputs will be left unconnected. These can float to invalid levels, and that can result in unexpected behavior and higher power dissipation.

-- Jeff

Right, it's more just to verify that I've not connected anything improperly (there's a re-settable fuse that should blow if I did). The power dissipation is a problem though, and that's what I was worried about with the clock left floating. I suppose I'll just wait till the parts come in, rather than risking it now.

So I'm writing an assembler based on this information and a few other resources, in here, it seems to say that (dir, X) addressing mode for say ADC can only be used with X, and (dir),Y only with Y, is this true? or are X and Y interchangeable here? I plan on using this assembler to build bytecode for my machine from text files, also, I'm going to look at writing an emulator that has some peripherals like the text panel on mine, to play around with and use for testing.

I actually just answered my own question. Since using X or Y in an operand makes that a different opcode then it necessarily cannot be interchangeable, since those other opcodes do not exist. Sorry for the dumb question, when I get this finished I'll get it uploaded somewhere around here, I'm writing it in java so it should work fine on any system.

Just got through re-reading some of the programing information Garth has on his site, and took a look at his feature requests for any new assemblers being made. This assembler is turning into a slightly larger project than I had hoped when I started it 12 hours ago, but I still intend on finishing it, and trying to tie in all the requests Garth has, I'll start a thread on it soon so people can chime in if they're interested.

I got the eeprom in today and I'm having some trouble programming it, I've started a thread here to discuss it, any help is appreciated, I'm losing hair by the minute.

Thanks for starting a new thread!

So I haven't been back to this thread for a bit, thought I'd post a bit of status on the project.

I wrote the display driver, and have the RTC working, so last night I got the display showing the current time and date:
(the month was set wrong in the image, I fixed that afterwards)

Today I'm going to see about setting up a rudimentary audio driver that will use VIA2's Timer 2 clock output to output square wave frequencies for a set amount of time.

I'll set up a git repo soon to share my assembly code, after I've finalized it a bit more.

So, quick question, I'm using some leftover push buttons for a simple user input board. I've got 9 of them, and I've arranged them into 3x3 rows and columns. My plan is to do a matrix keyboard here, and I'd like to set up some hardware debounce to simplify initial software for them (although I will be implementing software debounce as well). My question is, should I be using a capacitor to ground from one column of button signals? I'm using 0.1uf caps that I have laying around. I'm just not sure if I need a cap at every button, or exactly what the organization should be with it.