Secur-a-stor, SMD disk replacement, cdc disk drives

Overview
The Secur-a-stor disk system is a real-time SMD to ESDI interface converter with a built-in ESDI disk drive. The disk system consists of an SMD-to-ESDI interface adapter electronics board, a 5-1/4 inch ESDI fixed disk drive, front panel switches and indicators, rear panel SMD A and B dual port cable connectors, a fan and a power supply packaged in a 5-1/4 high 19 inch rack mountable chassis.

The Secur-a-stor disk system provides media removable capability via a disk drive mounted in a canister which slides into the chassis from the front and rests on slides attached to the chassis walls. All electrical connections between the drive unit and the main chassis are mad via a 96 pin DIN connector. A compact 5-1/4 inch drive can be handled easily as a removable unit. The DIN connector is a low insertion force (LIF) connector designed for high level of insertion cycle activity.

The Secur-a-stor 9766 SMD disk drive emulation allows the disk system to directly replace a removable pack CDC 9766 drive and operate compatibly with Encore, Class E and F, SMD disk controllers.

Encryption
The disk system provides a hardware data encryption for data security. This will prevent casual deciphering of data by either other disks units or non-disk systems.

The disk system encrypts each sector header field during disk format operations with a code unique to each disk system. The encryption code is generated from a 4 hexidigit thumbwheel switch on the front panel.

Media
The media provides a perfect media disk drive. It manages media defect reallocation locally. This capability is used to satisfy the requirements of a certified disk pack for removable drives. The WREN drive media defect information is stored in two disk address mapping PROMS. The media flaws are identified by track (head) address and cylinder address.

The two address mapping PROMS are physically located on a PC board in the disk canister assembly since the media defect information stored on these PROMS are unique to each drive. Thus, when the drive is removed from the disk chassis the defect list information stays with the drive.

SMD
The disk system supports the SMD interface characteristics for single and dual port feature. The SMD serial data and the associated timing signals are directly in real-time to their corresponding ESDI serial data and timing signals. The following is a summary of mayor SMD interface characteristics.

9.6768 mbits/sec or 1.2096 mbytes/sec.
20,160 bytes/track.
5/19 Others data heads.
823 Others cylinders.
Tag 1 (cylinder select). Tag 2 (head select). Tag 3 (control select).
Unit select tag and 4 unit select bits.
Hard sectoring and soft sectoring.

The difference in the number of heads per cylinder, i.e., 15 and 19 heads per cylinder for WREN V and 9766 respectively, requires the WERNE V to perform seek operations necessitated by disk address mapping.

Self Test
The disk system performs self-test upon a power –on condition. The result of the self-test will be indicated by the four led indicators on the SDM-to-ESDI-Interface adapter board.

Physical
The disk system is packaged in a self-contained 19 inch rack mountable chassis. The chassis has dimensions of 5.21 inches of height by 19.00 inches of width by 18.00 components including the WREN drive weighs approximately 34lbs. The system is mounted in a 19 inch rack with four bolts. It requires 5.25 inches of vertical rack space.