Your 10.4 disc pre-dates the OS with which your Mac shipped; Macs cannot boot from such discs. True enough. I just dug up the grey install disks and they're 10.5.4 ryck
ryck
"What Were Once Vices Are Now Habits" The Doobie Brothers
iMac (Retina 5K, 27", 2020), 3.8 GHz 8 Core Intel Core i7, 8GB RAM, 2667 MHz DDR4
OS Sonoma 14.4.1
Canon Pixma TR 8520 Printer
Epson Perfection V500 Photo Scanner c/w VueScan software
TM on 1TB LaCie USB-C
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