This is totally by-product inside 6809 project since it is working by Z80. Here you see very simple (simplest? ) Z80 system with PS/2 keyboard and monitor support. Left board contains LPC810 working as serial console, and right one AKI-80, which I bought just by 500JPY. ( Raspberry Pi Zero comparable ?? ;-)
"AKI-80" was sold by Akizuki denshi tusho in Akihabara (Japanese site), Tokyo in early 1990's. This board had some evolution from original AKI-80 (this board), AKI-80 gold (32kB SRAM) and Super AKI-80 (including RS-232C interface). They still sell Super AKI-80 by 4980JPY (including monitor ROM and C compiler for Z80) but this time I got "dead stock" of original AKI-80 just by 500JPY. They already stopped sales of non-super AKI-80 but full information (Japanese) still can be found at their site.
My board was just "board" and without any additional parts (X'tal, capacitors, auto reset IC) and I put several modifications (so not auto-reset)
This Z80 is not simple surface mount package but...
IT IS Highly integrated version of Z80 (TOSHIBA TMPZ84C015) containing Z80-SIO, PIO, CTC, and CGC just in one chip! Unfortunately this Z80 is already out-of-production but even now you can find 2nd source by Zilog at digikey. (Indeed, this is quite rare case, Zilog sells Toshiba's original product...) As a consequence of high integration, minimum computer, consisting serial I/O, can be made just with additional RAM for main memory and ROM for firmware. This time (sometimes happens to me, though), I just write EP-ROM by hex file released by great programmer (NOT ME) at http://www.amy.hi-ho.ne.jp/officetetsu/sbc/sbc/devel/devel.html (TBZ80.zip). Console is made of LPC810, this is also not my original one (information can be found at http://www.recfor.net/blog/mycom/?itemid=907 Seriously this is great masterpiece of LPC810 application!!!) and working well between PS/2 keyboard, Monitor, and AKI-80. Connection between AKI-80 and LPC810 console can be derived from this image( in this link MAX232 is connected. Instead of it, just connect with LPC810 console..) In fact, this image is a part of Japanese book and full information about this type of RETRO computer can be found by this Japanese book, written by TinyBASIC author of above link.
Actual operation can be found in the following movie.. I would thank all the original authors for releasing their great works on the web. Have fun!