Полигон-2

[q]

PRINT HEX$(INP(&H3F0))
9 Ok

PRINT HEX$(INP(&H3F1))
63 Ok

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[q]

Although 3.5" floppy disks were becoming common in the industry by 1987, the PS/2s were the first IBM models to use them as standard, relegating the 5.25" format to an expensive, optional external accessory drive. While the disk format itself was standard, IBM chose to use a non-standard form for the disk drives, resulting in very high repair costs as a standard drive could not be retrofitted to a PS/2. The IBM part was functionally identical to a standard 3.5" floppy drive, but about five times more expensive.[citation needed] In the initial line-up, IBM used 720 kB Double Density (DD) capacity drives on the 8086-based models and 1.44 megabytes High Density (HD) on the 80286-based and higher models. By the end of the PS/2 line they had moved to a somewhat standardized capacity of 2.88 MB. The PS/2 floppy drives were famous for not having a capacity detector. 1.44 MB floppies had a hole so that drives could identify them from 720 kB floppies, preventing users from formatting the smaller capacity disks to the higher capacity (doing so would work, but with a higher tendency of data loss). Clone manufacturers implemented the hole detection, but IBM did not. As a result of this a 720 kB floppy could be formatted to 1.44 MB in a PS/2, the resulting floppy only be readable by a PS/2 machine afterwards.

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