Also, a thought just occurred to me: is there anything stopping one from using a simple eprom/eeprom as an address decoder, aside from general wastefulness of a complex and useful chip on boring housekeeping functions? This would give us software-controlled glue logic without exotic software or ...

I'd like to play with some PALS/GALS, but I don't really know where to start. Does anyone know of some kind of "complete idiot's guide to programmable logic"?

Do you really think there will ever stop being a market for something as ubiquitous as nand gates, flip flops, or decade counters? I see such a future being a long way off, even if it does mean us hobbyists' beloved wire-wrap-able, dead-bug-able DIP-style 74xxx chips aren't available, I would think ...

Indeed. It's got most of portC open if you don't want the "controller" buttons, and all of portA. The C API is really pretty remarkably clean and complete, for uC code(I'm used to staring at pages of assembly rather than prettified GNU C), but a 6502-facing interface for the complete capabilities of ...

http://avga.prometheus4.com/
This looks very cool. Someone's done all the tedious parts of writing an entirely interrupt-based software video generator for sub-$5 Atmel AVRs (plus the cost of a programmer), making it possible to add one-chip video to any project. Once I get my Hunley up and ...

http://socialkonstrukt.com/hunley-6502rev3.gif
How's this look? I'm still thinking about the keyboard. ASCII encoded keyboards seem to be in short supply. I think I'll start with a hex keypad, like the micros of yore, just a 4x4 matrix hooked straight to one VIA.

I'VE GOT IT!
http://socialkonstrukt.com/garthsdecode2.gif
This is exactly the memory map I was looking for, and still only two (simple, standard, cheap) chips! Plus, I could use inverters anyway to interface the LCD display, so the extra chip won't be going entirely to waste. My only concern is ...

I'm probably missing something, but that would seem to do it while still using just one chip. What am I doing wrong? It all seems to check out in my illegible scribbles and bleary eyes.
http://socialkonstrukt.com/garthsdecode.gif

Is there a way to modify this decoder setup to have 32k RAM and 16 ROM instead of the other way around? If you just switch them around, then the reset vectors is somewhere in a sea of RAM. The memory map I'm trying for is like this, or something similar, as long as I have more RAM than ROM.

$0000 ...

I'd like to use one of these 65xx family ACIAs in my project, but I can't seem to find a source for them. Where can I find these chips and, if it's simply not possible to find them without tearing apart old commodores or something, what would be a suitable alternative that is currently available?

Thanks a lot Garth. You're a nice guy.

Garth, could you shed some light on my previous question. Specifically, if you never read from the display, how do you ascertain whether its busy or ready to accept input?

Another question: Why, in Garth's 74x00 address decoder, does the RAM need to be gated with phase2, but the ROM doesn't?

What do you do about the busy flag? just do your own timing to figure out when it should be free again?

Garth, you said you have some experience with this type of lcd. If I'm running at 1mhz, would it be better to hang it off a VIA, or to put it straight on the bus. I ask because I'm digging through the datasheets, and it seems like the programming will be greatly simplified if it's directly on the ...