| Number | Name | Date | Kind |
|---|---|---|---|
| 4062049 | Dirks | Dec 1977 | |
| 4593192 | Slattery et al. | Jun 1986 | |
| 4752911 | Prevost et al. | Jun 1988 | |
| 4833554 | Dalziel et al. | May 1989 | |
| 4870643 | Bultman et al. | Sep 1989 | |
| 4912580 | Hanson | Mar 1990 | |
| 4956733 | Dalziel | Sep 1990 |
| Entry |
|---|
| IBM Technical Bulletin vol. 30 No. 8 Jan. 1988 "Security Device for a Disk Drive". |