Tandy 600 Programmer's Reference Manual page 182

INT
59h,
Function 7
-
Configure Serial
Device
Entry:
AH
=
7
(function
code)
AL
=
Configuration
parameters
bits
0-1
-
number
of
data
bits
00
=
5
01
=
6
10
=
7
11=8
bits
2-3
-
number
of
stop
bits
00
=
1
01
=1.5
10
=
2
11
=
not
allowed
bits
4-6
- parity
selection
000
=
none
001
=
ignore
010 = even
011
=
odd
100
=
mark
101
=
space
bit
7
-
XON//XOFF
flag
=
XON/XOFF
disabled
1
= XON/XOFF
enabled
BH
=
XON
character
BL=XOFF
character
CX
=
baud
rate/100
(except
110
baud, which
is
specified
by
CX
=
0)
Exit:
FLAGS.
C
=
return
code
-
no errors
1
-
illegal
configuration
parameter(s)
INT 59h, Function
8
-
Return Receiver Status
Entry:
AH =8
(function
code)
Exit:
AL =
Standard
BIOS
error
code
CX
= number
of
bytes of free
space
in
queue
DX
= number
of
bytes
in
queue
INT 59h, Function 9
-
Fetch Receiver Data
Entry:
AH =9
(function
code
Exit:
AL=
Standard
BIOS
error
code
FLAGS.Z=0
-
data available (data
is
in
AL)
1
-
no data available
AH =
data
byte
(if
FLAGS.Z
=
0)
177