Jumper Configuration

This page explains the function of each jumper on the SolderDemon rosco_m68k mainboard and how to configure them safely.

Incorrect jumper configuration can lead to unstable operation or permanent hardware damage. Please read carefully before changing any settings.

JP1 / JP2 — FTDI Power (Legacy Connection)

Purpose:
JP1 and JP2 allow the board to receive power directly from the FTDI module.

⚠ Important Rules

• Never short both at the same time.
• Do not use JP1/JP2 if external 5V power is connected.

Failure to follow these rules may damage:

• The rosco_m68k board
• The FTDI module
• Your power supply
• Connected equipment

Current Requirements

When powering the board via FTDI:

• The system requires at least 500mA for the mainboard alone.
• Many computers and FTDI adapters cannot reliably supply this current.

If the current requirement is not met:

• The board may behave unpredictably.
• In rare cases, permanent damage may occur.

If you are unsure, use a proper external power supply instead.

JP3 — Flash Write Enable

Purpose:
JP3 enables hardware-level write access to the Flash ROM.

Behavior

• Shorted → Flash ROM writing enabled (required for firmware updates).
• Open → Flash ROM writing disabled at hardware level.

Even though software protections exist, leaving JP3 open prevents any accidental writes at the hardware level.

Recommended Usage

• Keep JP3 open during normal operation.
• Short only when intentionally flashing firmware.

This provides an additional safety layer.

JP4 — Expansion RAM Mode

Purpose:
JP4 modifies memory mapping behavior for compatibility with the original rosco_m68k memory expansion board.

Behavior

• Shorted → Enables compatibility mode for original memory expansion board.
• Open → Standard configuration (recommended for most users).

Recommended Usage

Unless you are using the original rosco_m68k expansion RAM board:

→ Leave JP4 open.

Quick Reference Table

If in doubt, leave all jumpers open and use a regulated external power supply.