Okay, I have been planning this for a long time (well about 6-7 months now). My idea is to make a "computer". Let me explain, I want to build a "computer" with a micro controller. My plans are to use a combination of point to point soldering and wire wrap. I want to mount this on I assume what is perfboard (board with many holes and no conductive stuff on it). I plan to use a PICAXE 18X. I want to implement a expansion bus, with an array of maybe 2-3 edge connectors. I would use a ULN2803A darlington driver between the edge connector and the micro-controller correct? I also plan to put on another different pin size edge corrector to contain the eproms for software. I am also planning to stuff this whole board in to a normal computer case. I haven't really spent much time looking in to the circuit for the eprom, The one I am looking at is the 24LC512 made by Microchip, because I know of another guy who used to one with this microcontroller and it seems to be able to suit my fine. I want to construct a circuit on a small 2inx.5in perfboard, which will contain 4 of these, what is required for this? Does anyone know of what I would need to get VGA out of this micro-processor?
http://www.multilabs.net/ezVID_20.html using basic, I doubt you would have enough processing power to bit bang VGA. I think if you're serious about this, you might want to switch over to assembly, but still, I kinda fail to see your goal...
I've thought about doing that to. Microcontrollers are computers all in one unit. The program storage, CPU, ram, control pins, etc all in one unit. I've been kicking around the idea for a while myself but not sure where to start. I've found PICputer www.picputer.com which is a basic interpreter in a PIC. The above video link is neat. I saw they also have VGA www.multilabs.net/ezVGA_SM.html. Still kicking around the idea in my head. If I come up with anything I'll post it.
crazy: you may want to look into the LX Geode processor from AMD. Essentially its a large scale integration chip, in layman's terms, a computer on a chip. These are meant to compete with VIA's C7 stuff but i think AMD's are actually a bit better. And of course they are full 32-bit compatible with linux and xp. As an alternative to the LX processor you could look at a via epia box. However if you are hell bent on writing drivers for a pic i would look into an atmel AVR in fact ive seen a few kernel attempts floating around for avr, should be able to google it. -chorlick
you'll have quite a problem driving full VGA off a PIC, especially if you are trying to do other calculations, even the 18 series. you could consider using an FPGA or CPLD interfaced to the PIC as a 'graphics' processor, though even if you know what you are doing with FPGAs youll need a hefty amount of time to do such a thing, assuming you have the budget (£150 ish) try Digilent, the FPGA development board im using for my university dissertation actually has a VGA and PS2 port included, and the user manual has some info on how to use them. if i were you though i'd say screw that, and use a graphic LCD or alphanumeric LCD... whatever you can do with a PIC, you wont be alble to make particularly impressive graphics anyway...
Try the Propeller chip from Parallax http://www.parallax.com/propeller/index.asp It's a 32Bit Micro with !!8!! Cores and the ability to directly drive VGA Displays. It should have enough power for you! (And most important it doesn't cost a fortune)
Figure that at 640x480, 24 bit color, and 60Hz, you have 18432000 pixels to push in a second. Your color depth will be the determining factor in how fast your microcontroller needs to go. You will need some DACs that can also go that fast to output on each color line. If you only want monochrome, all three lines can be tied to one DAC. Speed is also affect by how much data you can write out of the microcontroller at a time, but if you can manage monochrome with one microcontroller, you could try having three so one can handle each color channel. Then you only need to worry about something that can feed the output buffer fast enough There are tricks you can use to cut down on the refresh rate and resolution internally, but VGA will need the horizontal and vertical sync pulses to indicate at least a 640x480 image at a minimum of 60hz horizontal refresh rate, so whatever you use to drive the display should be able to handle this.
I don't know about VGA, but I know you can drive an LCD display from a Gumstix. I'm sure with a little hacking (And a TDMS chip, or whatever it is) you could convert the TTL LCD signals to VGA...
Just a heads-up, If you follow a previous suggestion of using the Parallax Propellor ( http://www.parallax.com/propeller/index.asp ) The graphics libraries that they have for their high level compiler is here: http://ww1.parallax.com/Default.aspx?tabid=65
I just interfaced a PS/2 keyboard to a microcontroller as part of a final project for a class. It's pretty easy. Info here: http://www.seas.upenn.edu/~cameronp/ese350/hardware.html#keyboard
