in one chassis. There are twelve models of the IBM 3380 family: six A-units, five B-units and one C-unit. A-units (heads of string) contain additional logic to perform string controller functions and connect to IBM directors or equivalent integrated attachments. The C-units connect to an IBM channel rather than a director. B-units connected to A-units or C-units. A string of 3380s with 16 actuators could provide from 10.08 gigabytes to 60.5 gigabytes, depending on model configuration. The last models were withdrawn by IBM in May 1996 representing a production run of 15 years; a run longer than most disk drives IBM 3390 The IBM 3390 Direct Access Storage Device series was introduced November 1989, offering a maximum storage of up to 22 gigabytes in a string of multiple drives. Cost of a storage system varied by configuration and capacity, between $90,000 and $795,000. Packaged in Hard Disk Assemblies with 2 actuator-head units and one set of platters, a model 1 HDA provides 1.89 GB before formatting and a model 2 provides 3.78 GB/HDA. The Model 3 enhancement to the drive family, announced September 11, 1991, increased capacity 1.5 times to 5.67 GB/HDA and the Model 9, announced May 20, 1993, further increased capacity 3 times to 11.3 GB/HDA, totaling 34 GB in a single cabinet, or 544 GB per storage subsystem. The 3390 Model 9 was the last Single Large Expensive Disk (sometimes called SLEDs) drive announced by IBM. IBM 9340 and 9345 IBM 9345 The IBM 9345 HDD first shipped in Nov 1990 as an RPQ on IBMs SCSE (SuperComputing Systems Extensions). Developed at IBM's San Jose, California laboratory under the code name Sawmill. It was an up to 1.5 GB full height 5-inch HDD using up to 8 130 mm disks. It was the first HDD to use MR (Magneto Resistive) heads. IBM 9340 In October 1991 the 9345 DASD was announced as part of the IBM 9340 channel-attached, count key data (CKD) DASD subsystem family which attached to IBM mainframes including the ES/9000 processor family. The 9345 DASD Model 1 had two 1.0 GB HDDs while the Model 2 had two 1.5 GB HDDs. For most practical applications, the 9340/9345 was functionally equivalent to a 3990/3390, although without non-volatile RAM cache of the 3990 and with a somewhat shorter maximum block length than the 3390. The OS's IOS component learned of this device's characteristics through a special