The Arduino SD library uses 512 bytes of RAM to store an entire sector and some extra RAM; serial ports libraries and printf stuff also suck some memory: this is why the free RAM of the ATmega dropped from 8k to about 6600 bytes. I bet the largest block available should be a bit less than six kilobytes.
Current status:
- 4x40 display: works, but I was unable to do anything more than 7-bit text. I tried to build custom characters but it just didn't work, even in the lower half display
- piezo beeper: works
- microSD: works
It's almost time to work out a keyboard.
Next step will be implementing some BASIC interpreter. Man, I hate BASIC, but now I can't figure anything better. A Forth interpreter is just lame; a Pascal interpreter seems useles; a C interpreter could be too complex. I also hate prehistoric stuff like COMIT, Algol, SNOBOL and exotic stuff like Logo, PL/M, REXX.
Well, I'll have to design my own interpreter and editor. It should have the same basic features of a common home-computer of the 80's: execute commands directly or after editing a program listing, easy to learn and use, integers, floats and strings operations, no baroque features, no Commodore PEEK/POKE-bloat.
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