IBM System/7 Functional Characteristics - All about the IBM 1130 ...

FUNCTIONAL DESCRIPTIONThe IBM 5022 Disk Storage Module is a bulk data storage device that provides the System/7with direct-access storage capability. Models 1 and 2 of the disk storage module can storea maximum of 2,457,600 data words; models 3 and 4 can store a maximum of 1,228,800data words.Models 1 and 2 of the disk storage module incorporate two disks, one above the other.The upper disk is contained in a disk cartridge (Figure 15-1) that protects the disk whenit is removed from the drive and used for offline storage. Models 3 and 4 incorporate asingle disk that cannot be removed.As many as 12,288 words (model I or model 2) can be transferred to or from the diskwithout repositioning the read/write elements of the module. Data is transferred to andfrom the disk at a maximum rate of 99,500 words per second. Models 1 and 3 differ frommodels 2 and 4, respectively, only in the time required to move the access mechanism. Thistime difference is described later in this chapter under "Seek Time."Direct program control (DPC) for data operations is standard equipment on all.fourmodels. An optional feature, 5022 Disk Cycle Steal (CS), is available. CS allows transferof up to 3,072 words with only one read or write command. DPC is mutually exclusivewith CS.Figure 15-1. Disk cartridge15-2 GA34-0003