The data output swing from 0V to -12V and the tape motion pulses must be negative going. This circuit will shift these signals for the IBM PC Parallel Port. The transistor can be any general purpose switch such as the 2N2222 and the diodes are standard signal types.
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| IBM PC Parallel Port | ||||
| I/O Address | Bit Number | Name | ( I )nput / (O)utput | DB-25 Pin Number |
| LPTbase+0 | 0 | DATA0 | I/O | 2 |
| 1 | DATA1 | I/O | 3 | |
| 2 | DATA2 | I/O | 4 | |
| 3 | DATA3 | I/O | 5 | |
| 4 | DATA4 | I/O | 6 | |
| 5 | DATA5 | I/O | 7 | |
| 6 | DATA6 | I/O | 8 | |
| 7 | DATA7 | I/O | 9 | |
| LPTbase+1 | 3 |
INPUT0 ~Error/Fault |
I | 15 |
| 4 |
INPUT1 SLCT (Online) |
I | 13 | |
| 5 |
INPUT2 Paper Out |
I | 12 | |
| 6 |
INPUT3 ~Acknowledge |
I | 10 | |
| 7 | ~BUSY | I | 11 | |
| LPTbase+2 | 0 | ~STROBE | I/O | 1 |
| 1 | ~AUTOFEED | O | 14 (Blue/Violet) | |
| 2 | RESET | O | 16 | |
| 3 | ~SELECT | O | 17 (Yellow) | |
| 5 |
Data Direction Control
for LPTbase+0 Register 0=Output 1=Input |
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| Signal Ground | 18, 19, 20, 21, 22, 23, 24 and 25 | |||
| LPTbase I/O Address | Printer Port |
| 0x378 | LPT1 |
| 0x278 | LPT2 |
| Visitor # |
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