This is the PARTNER-N64 PC development kit for the Nintendo 64. This unit was made for Nintendo by the company Kyoto Microcomputer (KMC). An in-depth video demo of this dev kit is shown further below. These cartridges provided real-time debugging features, however many developers still preferred using the SN-Systems “SN64” development kits.
The Partner-N64 debugger system does require a specially modified N64 console, in order to work correctly. This special N64 console gave the Debugger software control over the hardware to activate two specific features: Trigger a Halt of the game for executing Breakpoints (IRQ), and Trigger a Reset of the N64 console (RESET).
There were two versions of the Partner-N64: Partner-N64PC for IBM compatible computers running Windows 95/98, and Partner-N64NW for developers using Silicon Graphics (SGI) Workstations. The Partner-N64 development kits provided debugging features for the N64, as well as for the failed 64DD development system.
An important note: There were actually two versions of the 64DD. One was the Retail version with a Black colored bezel. The second was the 64DD Development version, only available to Nintendo 64 developers, identifiable by its Blue bezel. These prototype models were made by ALPS ELECTRIC CO LTD.
Source: Hacker News · Summarized by HeadlinesBriefing