IBM PC Family  -  Copying a BIOS ROM to a file


WARNING:   The copy is how the CPU sees the data.
In some cases, that copy will be unsuitable for creating a replacment ROM.
See note 1 below.


EXAMPLE:  8 KB sized ROM at address C8000

1. Boot from a DOS boot disk that contains DEBUG.COM
   
2. Execute DEBUG.  DEBUG will present a dash ("-") prompt.  When you see that prompt, enter the following commands (shown in brown):
   
 
- n myc800.bin (Comment: Resulting file will be named MYC800.BIN)
- r bx (Comment: We will now set BX=0000H/CX=2000H as count of bytes to write to file, 00002000H = 8K)
BX 0000  
: 0 (Comment: BX = high-order file size = 0000)
- r cx  
CX 0000  
: 2000 (Comment: CX = low-order file size = 2000)
- m C800:0 2000 0100 (Comment: Copy 8K bytes from C800:0 to offset 0100 in local segment)
- w 0100 (Comment: Write from offset 0100 in local segment to file)
Writing 2000 bytes  
- q (Comment: Quit to DOS)
 
   
3. You will see a file named MYC800.BIN





Note 1 Read the "Be aware ..." paragraph in this.