A music medium designed by Sony as a portable replacement for music Compact Discs. In 1994 Sony announced a data version which can hold 140 MB or about 100 MB using error correction. These will be competitive with 128 MB magneto-optical disks. Mini Discs may be either a re-writable or mass-produced read-only type. Sony have also announced a standard data format.
The transfer rate is similar to CD-ROM which is slow compared to the current magneto-optical drives (which are similar to an old hard disk, with writing noticeably slower than reading). Pre-recorded read-only Mini Discs can be mass manufactured on a modified CD press - this and the standard format mean it could take off as a software distribution medium.
An article in the December 1994 PCW quotes access times of about 300 ms and data transfer rate of about 150 kb/s (i.e. about single spin CD rate).