A small character-based LCD should serve as a cheap and easy to use output device for a minimal SBC[*]. The idea is that you send 8-bit data and the display device itself has the character definitions, typically in a 5x8 grid. The cheapest offerings are not pixel-addressable - no bit mapped graphics, although the character definitions can be modified. Sizes range from 2 lines of 8 characters to 4 lines of 20 characters.

For examples from $10 and up, see here.

A quick look at a datasheet implies such a device can be directly hooked up to the 65xx data bus, if the clock speed is no more than 2MHz. Or, at the cost of writing some software, it could be driven by a VIA or perhaps a trivial 8-bit parallel port - it can use a 4-bit data bus which needs only 7 lines for the interface. (An output-only port will have to wait out the display's busy period between commands, whereas a bidirectional connection can poll a busy bit.)

Anyone have any experience to share, or specific recommendations?

(I looked also at 7-segment LEDs, but the $2 directly connected ones demand that the software multiplex the digits, and the ones with a serial interface cost $13)

Cheers
Ed

[*] This thread seeks to build a minimal SBC for educational purposes. Part of the discussion is about I/O for such an SBC. Serial I/O to a host PC is relatively simple and cheap, but means hooking up to a powerful and expensive device.

As for implementing lcd displays with Hitachi controllers, i always like to cheat there, so every time i use a mcu, as for my sbc i have that interface of mine, that is very simple to use.
In one of by collage classes we discussed toes lcd displays, and the professor mentioned that they are a bit tricky to initialize, that they require some exact sequences to be sent to them at power up, if not they won't work.
By using a mcu, you can get rid of initializations and handling issues, and also you can use it as a ps/2 interface, and hook a cheap ps/2 keyboard.

I have a couple here of 4x40, and I've seen them in catalogs with lines up to 2x80.


so with a 4-bit interface, you only need 6 port bits, not 7. I'm using 6 on my workbench computer, just leaving enough time that I know each operation is done before doing the next, since I can't read the busy bit.


I've used them many times. I address them at the top of http://wilsonminesco.com/6502primer/displays.html, which also has a link to some code at http://wilsonminesco.com/6502primer/LCDcode.asm. This includes the initialization which can trip you up if you're not forewarned about it. For the web page, I simplified the code from what we actually used which loaded a lot of special characters. The different sizes of displays work pretty much the same, with just small differences in how individual characters are numbered. Electrically, 4x40 is really two 2x40's parallelled except for the individual Enable lines brought out so you only talk to one at a time.

_________________
http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?

Thanks Garth - that's good info. Good point about needing only 6 lines as a minimum, and thanks for confirming that this works in practice!