of I/O read/writes.
- * The NC200 does not have a TC8521 Real Time Clock, instead it
has a MC146818 Real Time Clock. The MC146818 is no longer produced now,
but is part of many PC designs.
- * The NC200 has a NEC765 compatible floppy disc controller. The disc
interface was designed by Ranger Computers.
bit 7 A15 bit 6 A14 bit 5 A13 bits 4-0 Not Used
Address = 20 Write only
Memory card wait state control
bit 7: memory card wait state control: 1 for wait states, 0 for no wait bit 2: ?? bit 1: ?? bit 0: NEC765 Terminal Count input (1=TC active, 0=TC inactive)
Address = 70
bit 2: Backlight: 1=off, 0=on bit 1: ?? bit 0: on/off control: 1 = on, 0 = off
Address = A0
bit 7: memory card present 0 = yes, 1 = no bit 6: memory card write protected 1 = yes, 0 = no bit 5: lithium battery 0 if >= 2.7 volts bit 4: input voltage = 1, if >= to 4 volts bit 3: ** unknown use ** bit 2: alkaline batteries. 0 if >=3.2 volts bit 1: ** unknown use ** bit 0: battery power: if 1: batteries are too low for disk usage, if 0: batteries ok for disc usage
Address = B0 - B9 Read only
B0..B9 each key of the 64 on the keyboard
will set a bit in one of these bytes
while pressed.
bit 7: ** unknown use ** bit 6: ** unknown use ** (Real Time Clock Alarm?) bit 5: NEC765 FDC bit 4: Power off interrupt bit 3 Key scan bit 2 TC8251 Serial Interrupt (Tx Ready OR Rx Ready) bit 1 ** unknown use ** (not checked by OS - not used?) bit 0 ACK from parallel interface
Address = 80
Printer status
bit 7..1: * unknown use * bit 0: printer busy status
1 = busy
bit 7: ** unknown use ** bit 6: ** unknown use ** (Real Time Clock Alarm?) bit 5: NEC765 FDC bit 4: Power off interrupt bit 3 Key scan bit 2 TC8251 Serial Interrupt (Tx Ready OR Rx Ready) bit 1 ** unknown use ** (not checked by OS - not used?) bit 0 ACK from parallel interface
Read:
E0 = Status, E1 = data
Write:
E0 = not used, E1 = data
[[NC100 IO Specification]]