Finding the specific "A799" driver can be tricky because HP sometimes classifies it under broader "POS" or "Receipt Printer" packages. Below are the most reliable sources.
often provides the most compatible "Universal MiniDrivers" for Windows 7, 8, 10, and 11. POS-Specific Drivers hp a799 thermal printer driver download link
Visit the HP Software and Driver Downloads Page Finding the specific "A799" driver can be tricky
Right-click the downloaded file and select . hp a799 thermal printer driver download link