Morrow Rev.1 Motherboards (MD-1 and MD-2 MicroDecision Computers) I/O Map --------------------------------------------------------- Port Function ---- -------------------------------------- 0F5 Motor Check Port 0F6 ROM Enable/Disable (output=enable, input=disable) 0F7 VFO Count Set Port 0F8 Motor and Shift Control 0F9 not assigned 0FA UPD-765 Status (Floppy Disk Controller Chip) 0FB UPD-765 Data (Floppy Disk Controller Chip) 0FC 1st Serial Port Data 0FD 1st Serial Port Status 0FE 2nd Serial Port Data 0FF 2nd Serial Port Status Morrow Rev. 2 Motherboards (MD-3 MicroDecision Computers) (Kohjinsha and Korean Motherboards, same schematic, different layout ) I/O Map Addendum ------------------------------------------------------------- Port Function ---- ---------------------------------------- 0F0 see below 0F1 see below 0F2 see next below 0F3 8253 Timer/Counter Used As Baud Rate Generator Ch. 1 and 2 0F4 Centronics Parallel Printer Port: Data Port 0F5 Centronics Parallel Printer Port: Status Port read bit 3 for ACK = 1 write bit 7 for STB = 0 read bit 4 for BUSY = 1 All Rev. 1 Ports remain the same except 0F5Hex, not needed for motor check. -Steve Walz rstevew@armory.com http://www.armory.com/~rstevew