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3. Interfaces
3.1 Parallel interface (Centronics)
1) Data input method: 8 bit parallel method (Data0 ~ data7)
2) Control signal: /ACK, BUSY, -STB, -ERROR, PE, SLCT, /INIT
3) Input signal to printer
Data 0 ~ data 7: 8 bit parallel signal (positive theory: PT)
/STB: Signal to read 8 bit data (negative theory: NT)
/INIT: Signal to reset whole printer (NT)
4) Printer output signal
/ACK: Last output pulse signal of busy signal at 8 bit data request signal (NT)
BUSY: Signal to indicate printer busy status and it inputs new data at "LOW" (PT)
/ERROR: Signal to become "LOW" at printer's alarm status. All control circuit stops (NT)
PE: Output signal at no paper status (PT)
SLCT: Signal to indicate on-line status (PT)
5) Input/output signal conditions
Input LOW level voltage
Input HIGH level voltage
Output LOW level voltage
Output HIGH level voltage
6) Input/output circuit
(if requested)
Abbr.
V IL
V IH
V OL
V OH
VCC
100
74LV14
VCC
74LV574
3.3k
510
1SS319
47
74LV14
47
74LV32
Min.
Typ.
0
-
0.7Vcc
-
-
-
0.7Vcc
-
STROB
IN PUT
PD0~PD7
IN PUT
INIT IN
IN PUT
ACK, P E, SLCT, ERROR
OUT PUT
BUSY
OUT PUT
7
Unit
Max.
0.18Vcc
V
Vcc
V
0.7
V
-
V
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