What does the power on self-test check?
The power on self test was introduced with RISC OS 3.0 and later versions of the OS. On power up your machine checks the hardware for physical faults before letting you use it, hopefully signalling important errors to you before further hardware damage can result. The purple screen at power on indicates that the self-test has begun. A brief ROM, RAM, VIDC and IOC test is performed and then the screen colour changes to blue and a limited memory test [1] is performed, along with a second test of the VIDC and IOC. When the screen returns to purple, the machine is testing for an ARM3 (or better). At the end of this sequence the screen colour is set to green (for pass) or red (for fail). If the tests have all passed then the machine starts to boot and the RISC OS 3 welcome screen is displayed. If any test fails, the screen will remain red and the disc drive light will blink a fault code. A short flash is used to indicate a binary ‘0’ and a long flash indicates a binary ‘1’. The bits are gro
The power on self test was introduced with RISC OS 3.0 and later versions of the OS. On power up your machine checks the hardware for physical faults before letting you use it, hopefully signalling important errors to you before further hardware damage can result. The purple screen at power on indicates that the self-test has begun. A brief ROM, RAM, VIDC and IOC test is performed and then the screen colour changes to blue and a limited memory test [1] is performed, along with a second test of the VIDC and IOC. When the screen returns to purple, the machine is testing for an ARM3 (or better). At the end of this sequence the screen colour is set to green (for pass) or red (for fail). If the tests have all passed then the machine starts to boot and the RISC OS welcome screen is displayed. RISC OS Select introduced some more tests (and screen colours). For detailed documentation on Select system initialisation, see select.riscos.com/prm/startup/systeminit.
