Specifications
Example
of
control
with
machine
language'
The example
of
program for controlling this printer with machine language
is
shown below. The
method
of
control varies, depending
on
the
ROM
unit used. The example shown below represents
reference subroutine program which constitutes the most basic part
of
the control.
• Control
as
printer for MZ-80B/MZ-80A
[Concept
of
printer control I
Start
.------+1
Checks BUSY signal
Yes
Is
the
printer
ON
LINE?
Transmits control
code
or printing
data code to the
printer.
Is
there
transfer
data?
No
[Printing data transfer routine I
No
No
29
Start
BUSY signal
input
Low level?
Transfers data
code
Makes
DATA
STH
signal high.
BUSY signal input
High
level?
Makes
DATA
STB
signal low.
Return
IN
A. (FEH)
~
Ace. - Data code
/
OUT
(FEH), A
S Ace.
+-
SOH
/
OUT
(FEll),
A
IN A, (FE
H)
[
When
the
printer]
receives data
code,
BUSY
signal becomes
high.
S Ace.
+-
oon
lOUT
(FEH), A