Return parameters
Register A
OOH
Normal open
A = 02H Busy (i.e., used
by
another program)
A = 04H Parameter error
Register
HL
contents are
not
changed
,------------,
_ 7
654
3
2
Z flag
Z flag
Z flag
1 0
1
o
o
(HL)
--
Flag (1B)
GET
Pointer
(2B)
1
L Lopen
Get
data
PUT
Pointer
(2B)
Receive
buffer
full
Buffer
Addr.
(2B)*
DeD
Buffer
Size
(2B)*
Parity
error
'----
Receive
over
run
'----
Framing error
'-----DSR
RSIOX (CLOSE)
Function: Closes the RS232C interface.
Entry parameter
Register B = 20H
RSIOX (INSTS)
Function: Checks whether there is any
data
in the receive buffer.
Entry parameters
Register B = 30H
Register
HL=
9 byte block address which is used
to
store return information.
Return parameters
Z flag = OlH Normal completion
Register A =
OOH
No
data
in the receive buffer
A =
FFH
Data
has been received
Register BC =
LOC
- Number
of
bytes
of
received
data
Register
HL
= Return information (See Open)
NOTE:
The meaning
of
LOC
relates to the value
of
PUT(Pointer) and GET(Pointer)
(see diagram under
RSIOX
(OPEN)).
5-24
If
PUTP
~
GETP
then
LOC
=
PUTP
-
GETP
If
PUTP
<
GETP
then
LOC
=
PUTP
-
GETP
+ Buffer size
Z flag = 0 Abnormal end
Register A = 03H - Interface
not
open
Register BC Unknown
Register
HL
Unknown
RSIOX (OUTST)
Function: Checks whether
output
is
enabled.
Entry
parameters
Register B = 40H
Register
HL
= Address
of
the block which is used
to
store reurn information
Return parameters
Z flag = 1 Normal completion
Register A =
OOH
Output
disabled
Register A =
FFH
Output
enabledl
Z flag = 0 Abnormal end
Register A = 03H Interface
not
open
Register
HL
= Not changed (For the
HL
contents, refer
to
the
OPEN
function.)
RSIOX (GET)
Function: Reads in one byte
of
data
from the receive buffer.
Entry
parameters
Register B = 50H
Register
HL=
Starting address
of
the block which is used to store return in-
formation
Return parameters
Z flag = 1 Normal completion
Register A = Receive
data
Register
HL=
Refer
to
the
OPEN
function.
Z flag = 0 Abnormal end
Register A = 03H Interface
not
open
A =
OOH
CTRL-STOP was pressed
Register H
L=
not
changed
5-25
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