Firmware file overview

Antminer-s21-aml-nand-v1.2.6-rc2-install.tar.gz

Antminer - firmware name
s21 - ASIC model
aml - control board type based on aml processor.
nand - firmware installation type directly into device memory.
v1.2.6-rc2 - firmware version.
install - firmware type (install - for installation, update - for updating already installed firmware).
tar.gz - file extension must remain unchanged.

Antminer-s19-xil-aml-1.2.6-rc4-instal.tar.gz

Name - Antminer Version - 1.2.6-rc4

Downloaded firmware files should not be unarchived.