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Download Technical Drawing for DB25 Male Parallel Port Loopback Tester Plug
DB25 Male Parallel Port Loopback Tester Plug
Parallel Port Loopback Tester
This loopback plug is designed for legacy parallel-port diagnostics and is commonly used with DOS-based PC diagnostic software, motherboard test utilities, industrial computer maintenance tools, and IEEE1284 troubleshooting applications.
Product Features
- Advanced IEEE 1284 control-line loopback diagnostic plug
- DB25 male parallel port loopback tester plug
- Used for external parallel port diagnostic testing
- Compatible with standard DB25 female parallel ports
- Useful for PC repair, legacy systems, and industrial computer testing
Loopback Wiring
Signals Pins Strobe / Select In 1, 13 Data0 / Error In 2, 15 Auto FD / Paper End 12, 14 Init / Acknowledge 10, 16 Select Out / Busy 11, 17 All other pins Open
Compatible Diagnostic Software
- IBM PC diagnostics utilities
- Norton Diagnostics / Norton SysInfo
- CheckIt diagnostic software
- QAPlus hardware diagnostics
- Legacy DOS parallel-port testing utilities
- IEEE 1284 bidirectional port diagnostics
- Super I/O hardware diagnostics
Best Compatibility
- DOS / FreeDOS environments
- Real motherboard LPT ports
- ISA or Super I/O based parallel ports
Limited Compatibility
- Generic Linux loopback utilities
- USB-to-parallel adapters
Common Applications
- Legacy PC parallel-port diagnostics
- Industrial computer maintenance
- Printer-port troubleshooting
- Motherboard and Super I/O testing
- DOS hardware diagnostics
- Repair bench and service-center testing
- Parallel-port verification for legacy systems
Legacy PC Diagnostic Hardware Specialists
PCCables.com supplies loopback adapters, diagnostic plugs, serial testers, and hard-to-find connectivity products for technicians, engineers, OEM repair, industrial maintenance, and legacy computer systems.
PCCables.com has tested this loopback plug on legacy IBM PC/XT-class systems using original IBM diagnostic software and DOS-based hardware test utilities.



