Department of Computer Science and Information EngineeringNational Cheng Kung University, TAIWAN
HANEL
OTHER MODES OF THE 8255Printer Signal(cont
’)
Indicates that the printer is in the state selected.
OUT
SLCT
--
13A “high”signal indicates that printer is out of paperOUT
PE
30
12A “high”signal indicates that the printer cannot
receive data. The signal becomes“high”in thefollowing case: (1)during data entry, (2) during printing operation,(3)in“off-line”status, (4)duringprinter error status.
OUT
BUSY
29
11Approximately 0.5μs pulse;“low”indicates datahas been received and printer is ready for data.OUT
ACKNLG
28
10““
IN
DATA 8
27
9““
IN
DATA 7
26
8““
IN
DATA 6
25
7““
IN
DATA 5
24
6““
IN
DATA 4
23
5““
IN
DATA 3
22
4““
IN
DATA 2
21
3These signals represent information of the 1st to8th bits of parallel data, respectively. Each signal isat “high”level when data is logical“^1 ”, and“low”when logical“^0 ”IN
DATA 1
20
2STROBE pulse to read datain. Pulse width must bemore than 0.5μs at receiving terminal. The signal
level is normally“high”; read-in of data is
performed at the“low”level of this signal.IN
STROBE
19
1Description
Direction
Signal
Return
Table 15-3. Centronics Printer SpecificationSerial