A method 20 and computer apparatus for using available 
firmware flash ROM space as a diagnostic drive. The computer apparatus has a nonvolatile 
random access memory, an Extensible 
Firmware Interface (EFI) and a basic input and output 
system (
BIOS). To implement the functionality provided by the present invention, a command shell of the EFI is modified to include the EFI driver and operates to configure available flash space normally reserved for 
firmware (
BIOS) as a diagnostic disk drive. The modified EFI and the EFI driver are stored in the 
flash memory. When the computer 
system 10 is initialized (booted), the EFI driver configures the available space in the 
flash memory that is not allocated to the 
firmware as the diagnostic disk drive. Diagnostic programs are loaded into the diagnostic disk drive, which are selectively run by a user, such as by using the command shell. The method may also be configured to include 
data compression and decompression routines to increase the quantity of data that may be stored in the configured disk drive space, or 
encryption routines for security purposes. The diagnostic disk drive space may be used to store 
power on self test (POST) error logs in files that may be read by the 
operating system during its boot process and displayed by an event viewer.