001
06.09.2025, 18:16 Uhr
Ordoban
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There should be a beep 8s after reset/switch on, and a shorter beep 2s later.
(if you get nothing here, the CPU is not even running, or the buzzer is broken)
(if you get a pulsing permanent tone here, the CPU cannot access the RAM)
After 10 more seconds there should be on more beep and some outputs starting on the screen.
(If you get more than one beep here, the CPU cannot access the graphics, or the graphics report an error)
Even more 15 seconds later there should be action on the floppy drives.
Since you report that you not always get the fist two beeps, I would think the ZVE (Main-CPU) is not running stable.
I would start by measuring the main (5V) supply, the CPU clock, CPU Reset signal, CPU S0-S2 signals.
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Gruß
Stefan |
