HP-85 HP-IB Interface

What this project covers

Bring-Up Phases

The interface is being developed and validated incrementally, with each phase establishing a known-good foundation for the next:

1. 01

   Pre-Power Inspection

   Verify component placement, wiring continuity, resistance, and the absence of shorts before connecting power or HP-IB equipment.

2. 02

   Power and Electrical Validation

   Confirm stable supply rails and verify safe signal levels across the 3.3 V controller and 5 V HP-IB logic domains.

3. 03

   Controller and Firmware Bring-Up

   Load diagnostic firmware on the Teensy and confirm local GPIO, timing, and serial diagnostic output.

4. 04

   HP-IB Signal Validation

   Exercise the data, handshake, and management lines individually through the level-translation circuitry.

5. 05

   Handshake and Addressing

   Validate listener and talker addressing, the DAV/NRFD/NDAC handshake, and expected controller interactions.

6. 06

   HP-85 Integration

   Connect the interface to the HP-85 and verify controlled communication using repeatable BASIC test programs.

7. 07

   System Qualification

   Run sustained transfers and compatibility tests with modern hosts and representative HP-IB devices.

Each phase limits the number of new variables introduced, allowing electrical, firmware, and protocol faults to be isolated before full HP-85 integration.

Current milestone

Current version

v0.2.0

Active phase

Phase 2 — Power and Electrical Validation

Last verified

Stable supply rails confirmed

In progress

Level-translation and HP-IB signal validation

Next milestone

Begin controller and diagnostic firmware bring-up

Visual record