HP41c Printer 82143A connector details

Hi, I am looking for the connector cable details of the HP82143A peripheral printer. Has anyone got the cable details or the circuit diagrams? Thanks for your help. Prabhu


Get a copy of Tony Duell's hand drawn schematics for this, it's got what you need. It's available here.


Do you mean the contacts on the module end that plugs into the HP-41? Those are described briefly in the HP-41 service manual, available on the MoHPC DVD set, or on TOS. See also "Inside the HP-41C" by Kelly McClellan, PPC Journal V6 N6 P4, September 1979, and "HP-41C Bus Interfacing" by Jim De Arras, PPC Journal V7 N3 P20, April 1980.

It's a 56-bit serial bus at 6.0-6.5V CMOS levels. Level shifters are needed interface to any normal logic, whether at 3.3V or 5.0V levels.

  1. Vbat - battery positive
  2. B4 - tied high or left open by port block in calculator, along with B3, to tell module which port it is plugged into, for port addressing
  3. Vcc -regulated power (6.0-6.5V)
  4. B3
  5. GND - ground reference
  6. PWO - power on reset
  7. DATA - 56-bit serial data word - 14 BCD or hexadecimal digits, little-endian (LSB first, LSD first)
  8. FI - flag input, used by peripheral to indicate that service is requested, during one digit time
  9. ISA (or IS/IA_ - instruction and address - serial 16-bit address (bit times 14 to 29), 10-bit ROM data (bit times 44 to 53)
  10. SYNC - high for bit times 44 to 53 (when instruction should be presented on ISA line), except during second cycle of two-cycle instructions
  11. Phi2 - bit clock - active-high - a bit time is generally between the falling edge of Phi2 and the next leading edge of Phi2
  12. Phi1 - bit clock - active-high - occurs near end of a bit time for use to strobe inputs (such as DATA, ISA, and SYNC)

If you mean the signals on the captive cable between the module and the printer, that's also a serial bus, but entirely different than the 41C bus. There's a description in the "Peripheral Interface Chip" (NPIC) internal HP documentation. The signals are:

  • GND
  • Vcc
  • DD0 - bidirectional data
  • DD1 - strobe provided by printer
  • DD2 - direction select, printer to NPIC when low, NPIC to printer when high
  • DD3 - printer power on, from printer to NPIC

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