Port Allocations

HUNTER uses the NSC800 port map for all its I/O functions, including the keyboard, RS-232, etc. The following gives a list of the most useful ports which can be controlled from Basic using OUT or INP verbs or from machine code.

Address Decimal

Hex

Name

Description

1

1H

DSR

Bit seven is the DSR Input bit. 1 = Inactive, 2 = Active

2

2H

INPUTS

This port has a number of input functions: Bit 0 is Data In (Inverted from RS-232 line). Bit 1 = DCD. Bit 2 = Power low warning (1 = Power O.K., 0 = Power low). Bit 3 = TXCLK - also the Single Bit Input Port.

96

60H

ANGLE

Controls display viewing angle. Input value in the range 0-1FH

129

81H

V24OUT

Directly outputs to the V24 data line signal on bit 0. The output is voltage inverted i.e. 0 = +Ve, 1 = -VE

130

82H

RTS

RTS output bit

131

83H

POWHLD

Power control. bit 0 = 1 : HUNTER on, bit 0 = 0 : HUNTER off

132

84H

INVCON

V24 inverter control. bit 0 = 1 : Inverter on, bit 0 = 0: inverter off

133

85H

DTR

DTR output bit

135

87H

AUXPWR

Turns on the auxilary power to pin 10 on the D type connector. 1 = Power on, 0 = Power off

187

BBH

ICRPFG

NSC800 internal interrupt mask register. See NSC800 hand book.

224

EOH

PAGE

Memory paging register