WTI Lasernet PSU-81B Printer Sharing Unit 256K 8-Port Serial Parallel Output

WTI Lasernet PSU-81B Printer Sharing Unit 256K 8-Port Serial Parallel Output

The WTI Lasernet PSU-81B is a 256K printer sharing unit made by Western Telematic Inc. (WTI) of Irvine, California. It allows up to 8 serial computer inputs to share a single printer, routing print jobs to either a parallel or serial printer output. Output mode, baud rate, parity, scanning method, and no-activity timeout are all configured via rear-panel DIP switches, making setup straightforward without software drivers.

Specifications & What's Included

• Model: PSU-81B (Lasernet series)
• Manufacturer: Western Telematic Inc. (WTI), Irvine, CA — Made in the USA
• Buffer memory: 256K
• Input ports: 8 x DB25 serial (RS-232) — labeled 1 through 8 on rear panel
• Parallel output: 1 x Centronics/DB25 parallel connector
• Serial output: 1 x serial output connector
• Baud rate (DIP SW 1–4): 1200, 2400, 9600, or 19.2K bps — independent input and output settings
• Parity (DIP SW 5): None or Even
• Scanning method (DIP SW 6): XON/XOFF or DTR/DATA
• No-activity timeout (DIP SW 7–8): 1, 5, 15, or 30 seconds
• Output mode (DIP SW 9–10): Serial Only, Parallel Only, Both (PIN 5+ = Serial), or Both (PIN 5+ = Parallel)
• Front-panel controls: CLEAR, PAUSE, TOF buttons
• Front-panel status indicators: WAIT, MEM, RDY LEDs; 8 INPUT LEDs (one per port)
• Power: 115VAC, 60Hz; IEC inlet with rear-panel ON/OFF switch
• Certifications: UL Listed — EDP Equipment 10T9
• Form factor: Desktop
• Includes: Unit only — no interface cables included

Applications

Printer sharing units like the PSU-81B were standard infrastructure in offices and print rooms of the late 1980s and early 1990s, when laser printers were expensive enough that sharing one across multiple workstations was a practical necessity. Before network printing became ubiquitous, a serial-input print buffer/switch like this was how multiple computers — typically running MS-DOS or early Windows — took turns sending jobs to a single laser or dot-matrix printer. The 256K onboard buffer allowed a computer to hand off a print job quickly and return to work while the PSU-81B fed data to the printer at its own pace. The WTI Lasernet line was well regarded in that era for its configurable DIP-switch architecture, which let administrators tune baud rates, parity, and scanning behavior to match a wide range of serial host equipment. Today these units see use in legacy environments that still run older serial-output systems, CNC machines, or any serial device that needs to share a single printer or output port.