Nintendo 64 Test Cart ROM | Hacker News Reader

Nintendo 64 Test Cart ROM

gamingalexandria.com

149 pointsecliptik16 comments

I assume a Test Cartridge is some kind of developer tool from back in the day?

Sounds from the article like it was used in factories, maybe to verify that a new production line or hardware revision is building consoles that function correctly?

Related and also interesting: https://tcrf.net/Category:Nintendo_Console_Testing_Software

Worth noting that (AIUI) such test ROMs are often used these days to test the faithfulness of emulators.

Clever!

it was also used during warranty/return phase to validate customer concerns. The production line usually checked the boards via the JTAG pins.

Did they take the JTAG pins off? I'm wondering why you would test differently on the way out of the factory and back in for repair claims

It's a lot easier to pop a cartridge in than to disassemble the case to get at the JTAG pins.

I don't think there necessarily ever were pins. JTAG on a production line is normally hooked up via a bed of nails.

These are called pogo pins

https://en.m.wikipedia.org/wiki/Pogo_pin

these care called a bed of nails

https://en.wikipedia.org/wiki/Bed_of_nails_tester

In addition to what the others said regarding disassembly, it's a lot easier to distribute (and train remote technicians to use/maintain) a test cartridge to service centers around the world than to set up the $xx,000+ bespoke bed of nails test fixtures that you would use on the production line.

JTAG doesn't really exist on the N64 hardware, it's only present on the CPU and the pins are hardwired to VCC/gnd.

Even if it did work, it wouldn't be sufficient to test the rest of the system, which doesn't have any concept of JTAG.

The other major chip (RCP) does have an undocumented test mode, it allowed the verification guys at SGI introspection into various registers/state by exposing them onto the cartridge bus as gpio. I don't think this is written down anywhere though.

Wow; this was fascinating!

Interestingly the world class service number in the SNES Aging test is still active!

It's a production test suite, designed for use with a custom jig that plugs into all the various ports to fully test everything, not just the cartridge. The custom test jig named 'zaru' which if I recall is Japanese for a rice strainer (appropriate for go/no-go tests) can be detected by the test suite and unlocks all the tests. It even controls the operator pass/fail lights on the jig from this software.

Also, authorized Nintendo service centers got the carts as a way to diagnose customer issues, but obviously without the factory jig.

The funny part is that the stress tests parts actually render all sorts of interesting 3d models that engineers inside SGI grabbed at random. The Utah teapot, a rocking chair, a cow, a VW beetle, the SGI logo itself. All rendered into an off screen framebuffer and checksummed.

There’s a ton of these designed in modern times for emulator development. I’m not specifically sure about this one though.

> I’m not specifically sure about this one though.

Curiously, details is in the article being discussed.

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