// // Official Kernal routine, described in: // // - [RG64] C64 Programmer's Reference Guide - page 299/300 // - [CM64] Compute's Mapping the Commodore 64 - page 232 // // CPU registers that has to be preserved (see [RG64]): .A, .X, .Y // SETTIM: // Disable interrupts for the duration of the routine, to prevent // jiffy clock update while changing it's values sei // Store the jiffy clock state sty TIME + 0 stx TIME + 1 sta TIME + 2 // Enable interrupts. More elegant solution would be pha + sei + ... + pla, // but (checked by running a test program) original ROM routine always // leaves IRQs enabled. cli rts