Hi Guys .
before I say anything here is a set of photos showing the board
Top Side :
Back Side
board size is 100x90 mm
chips used , top side
1.) atmega 128 - keyboard , SD card (fat32) , 2 serial ports (one ttl and one over ft232 (missing chip on the back side ),real time clock and few I/o pins , atmega is also controlling Reset and NMI and 3 LED's
2.) 74573 latch
3.) 2K x8 dual-ported ram ( $F800 - $FFFF)
4.) Atmega88 with SwinSid firmware (max clock 1.5 MHZ)
5.) WDC65816
6.) DS1307 (real time clock )
7.) XC95216 cpld in 160 pin package (*)
8.) 64KB x16 ram for color and screen storage (c64 text mode)
9.) 512KB x8 for font/graphic/system storage-memory
so on the top edge we have sound , usb(rs232) ,SD card ,PS2 keyboard and 8bit VGA connectors.
on the back side we have
1.) 74ls07 to translate voltages 3.3V to 5V - SD card interface
2.) audio amplifier
3.) ft232 chip (missing)
4.) 3.3v voltage stabiliser
5.) 32MHZ crystal oscillator ( overclocked atmega88)
the red wire you see is a link between battery and RTC chip.
at the boot atmega is searching for the rom.bin file on the sd card , if file presents contend is copied to the ram and system is started
work in progress.