BigDumbDinosaur wrote:
Connect the 2692A's IRQ output, as well as a pullup resistor, to your wired-OR circuit.
Ah. So we'd be looking at something like this?
Attachment:
ÜSq0 IRQ sws 20130410 V2.jpeg [ 73.5 KiB | Viewed 1137 times ]
Hard to argue with the simplicity and size. Since this SBC is only going to have a 2692A and one VIA 65c22, that will be just fine. Thanks!
The clock speed -- I'll try to follow the recommendations of the high-speed primer (
http://forum.6502.org/viewtopic.php?t=2029), but start out with 1 MHz as a goal. Of course I'm hoping it will work at faster speeds, but at this point, getting it to work
at all is the primary goal
![Very Happy :D](./images/smilies/icon_biggrin.gif)
.
As for the discussion about F vs HC and metal vs carbon resistors -- is there some entry in the forum I might have missed about the other logic families as related to the 6502? I've read the Primer entry (
http://wilsonminesco.com/6502primer/LogicFamilies.html), but now I've seen HCT, ACH, and F mentioned. I can look the general information up on them (
http://www.eng.yale.edu/ee-labs/morse/compo/logic.html for example, or
http://www.beam-wiki.org/wiki/7400_Families), but that doesn't tell me what to use for a 6502. For example, if F is so much faster, why don't I just use it for everything? (Judging from my catalogues, I'm guessing the F family doesn't offer all the chips available as HC.)
I know there are a bunch of real EEs here who can rattle this stuff down dead drunk at four in the morning, but for those of us who are coming from a software side and secretly always thought that logic chips are just another form of lego, seriously, how hard can it be, something as simple as "use metal resistors for wire wrap" or "use HC unless you want to be very, very fast, then use F" would be an enormous help and hopefully cut down on noob questions like mine (cough). Sorry if this is already on the forum and I missed it.
On that note, I should like to take this moment to say a big thank you again for the enormous amount of information and great help provided here. I don't think I've learned as much this quickly since college, if then. It's very much appreciated.
(
EDIT: Corrected drawing, thanks to Arlet. This was actually a very instructional mistake, because it made me realize I've been thinking in terms of how "the signal" is flowing (from the 65c22 to the 65c02) instead of the actual electricity. Still annoying, of course.)