Atari SX 212 Owner's Manual page 33

TABLE 3 S REGISTERS
Register
SI 5
SI 6
SI 7
S18
Function
Bit 4 off - command recog¬
nition enabled
on - command recog¬
nition disabled
Bit 5 reserved
Bit 6 reserved
Bit 7 reserved
Determines the modem's
operating parameters.
Bit 0 (same as bit 4)
Bit 1 (same as bit 5)
Bit 2 off = answer mode
on = originate mode
Bit 3 off = half-duplex
on = full-duplex
Bit 4 off = undefined if bit 5
is off or 300 bps
if bit 5 is on
on = 110 bps if bit 5 is
off or 1200 bps if
bit 5 is on
Bit 5 off = undefined if bit 4
is off or 110 bps
if bit 4 is on
on = 300 bps if bit 4
is off or 1200
bps if bit 4 is on
Bit 6 off - carrier signal off
on = carrier signal on
Bit 7 off - data terminal
ready signal
enabled
on - data terminal
ready signal
disabled
Reserved bit-mapped
register.
Reserved bit-mapped
register.
Reserved bit-mapped
register.
Default Range
off
0 to 255
on (1)
on (2)
off
on
on (16)
on (32)
off
off