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HP41c Printer 82143A connector details - Printable Version

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HP41c Printer 82143A connector details - Prabhu Bhooplapur - 06-16-2011

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

Re: HP41c Printer 82143A connector details - Katie Wasserman - 06-16-2011

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

Re: HP41c Printer 82143A connector details - Eric Smith - 06-16-2011

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