I want to build a https://github.com/rjw57/buri computer but I do not have access to either an ACIA or VIA chips, which i need for serial. As GPIO is not important for my use, I was wondering if I could program one of the larger atmegas to act as a serial chip. Has anyone had any experience with this? Thanks. Also, if anyone can suggest any way I could get the ACIA and VIA in hyderabad, india, please mention it.

Welcome! It looks like you can get an AVR to act as a peripheral to an 8 bit micro, at least at 1MHz, as the SwinSID project does exactly that. (I'm assuming it has to support both host reads and host writes.)

See
http://www.forum64.de/index.php?thread/ ... -atmega88/
where an ATMEGA88 is in play.
via
http://www.avrfreaks.net/forum/avr-para ... unications
http://www.avrfreaks.net/forum/interfac ... -direction
and see also
http://www.swinkels.tvtom.pl/swinsid/

(Others here may have more direct experience of this.)

Thanks. Those links are useful. Ill post my results, unless I find the VIA and ACIA in India somewhere.