Alpha version (Prototype)
Its divided into two cards.
Dragon Memory Card
This card contains a Dual Port SDRAM Chip connected directly to Dragon Computer expansion bus. And can accessed directy from Dragon Computer from address $C000.
USB Data Transferd Card
This card contains ATMEGA8515 microcontroller and Latch 74HC573 for attach DP-SRAM as a external microcontroller RAM.
This version serial works at 300 baud.
Beta version (Manufactured PCB)
The first single PCB board that contains all Memory+Data transferer. PCB are manufactured by PCBWay and designed with KiCAD.
Firsts test are go well, but I needed ajust SUT_CKSEL to Ext. Crystal/Resonator High Freq; Start-up time: 16K CK + 4ms and activate BODEN and CKOPT. (FUSES: 0xC1, 0xAF). This is a important note because other timming configuration not works very fine with this type of external RAM.
Finally adjusts serial speed to 9600 baud.