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 BSAVE/BLOAD File Format Explained for BASIC; 7-Byte Header - Q34407
 
 A file saved with the BSAVE statement has a 7-byte header with the
 following hexadecimal format:
 
    ww xx xx yy yy zz zz
 
    ww:     A signature byte equal to 253, which tells MS-DOS and other
            programs that this is a BASIC BSAVE/BLOAD format file.
    xx xx:  The segment address from the last BSAVE.
    yy yy:  The offset address from the last BSAVE.
    zz zz:  The number of bytes BSAVEd.
 
 This information applies to:
 
  - The Standard and Professional Editions of Microsoft Visual Basic
    version 1.0 for MS-DOS.
  - Microsoft QuickBasic versions 3.0, 4.0, 4.0b, and 4.5 for MS-DOS
  - Microsoft Basic Compiler versions 6.0 and 6.0b for MS-DOS
  - Microsoft BASIC Professional Development System (PDS) versions 7.0
    and 7.1 for MS-DOS
 
 This information is provided as is. The BSAVE format is not guaranteed
 to be the same in a future release.
 
 More Information:
 
 Microsoft GW-BASIC Interpreter (versions 3.2, 3.22, and 3.23) uses
 the same 7-byte header string, and also repeats the 7-byte string,
 appending it after the final data byte. BASICA (provided in IBM's or
 Compaq's ROM BIOS on some computer models) does not repeat the 7-byte
 string at the end. GW-BASIC and BASICA both terminate the file with
 ASCII 26, also known as a CTRL+Z character (1Ah). Visual Basic,
 QuickBasic and the Microsoft BASIC Compiler does not append a CTRL+Z
 character or repeat the 7-byte string at the end of the file.
 
 To determine whether a file was BSAVEd by GW-BASIC, BASICA,
 Visual Basic, or QuickBasic, compare the length of the memory saved
 against the file length. The difference is 15 bytes in GW-BASIC,
 7 bytes in Visual Basic, 7 bytes in QuickBasic, and 8 bytes in BASICA.
 
 Despite the slight format differences, files BSAVEd under any of the
 four above BASIC dialects correctly BLOAD into each other's BASIC.