IBM drum storage#IBM 2301
{{Short description|Drum storage devices manufactured and sold by IBM.}}
In addition to the drums used as main memory by IBM in, e.g., IBM 305, IBM 650, IBM offered drum devices as secondary storage for the 700/7000 series and System/360 series of computers.
IBM 731
The IBM 731 is a discontinued storage unit used on the IBM 701.{{cite manual
| title = Principles Of Operation Type 701 and Associated Equipment
| year = 1953
| url = http://www.bitsavers.org/pdf/ibm/701/24-6042-1_701_PrincOps.pdf
| access-date = May 22, 2021
| publisher = IBM Corporation
}}
It has a storage capacity of 2,048 36-bit words (9,216 8-bit bytes).
IBM 732
The IBM 732 is a discontinued storage unit used on the IBM 702.{{cite manual
| title = Type 702 Preliminary Manual Of Instruction
| year = 1954
| access-date = May 22, 2021
| url = http://www.bitsavers.org/pdf/ibm/702/22-6173-1_702prelim_Feb56.pdf
| publisher = IBM Corporation
}}
It has a storage capacity of 60,000 6-bit characters (45,000 8-bit bytes).
IBM 733
The IBM 733 is a discontinued storage unit used on the IBM 704{{cite manual
| title = IBM 704 electronic data-processing machine
| year = 1955
| url = http://www.bitsavers.org/pdf/ibm/704/24-6661-2_704_Manual_1955.pdf
| access-date = May 22, 2021
| publisher = IBM Corporation
}}
and IBM 709. It has a storage capacity of 8192 36-bit words (36,864 8-bit bytes).
IBM 734
The IBM 734 is a discontinued storage unit used on the IBM 705{{cite manual
| title = 705 Data Processing System Reference Manual
| year = 1959
| url = http://www.bitsavers.org/pdf/ibm/705/A22-6506-0_705_Reference_Man_May59.pdf
| access-date = May 22, 2021
}}
It has a storage capacity of 60,000 6-bit characters (45,000 8-bit bytes).
IBM 7320
The IBM 7320 is a discontinued storage unit manufactured by IBM announced on December 10, 1962{{cite web |last1=IBM Corporation |title=DPD chronology |url=https://www.ibm.com/ibm/history/exhibits/dpd50/dpd50_chronology2.html |website=IBM Archives |access-date=Dec 6, 2019}} for the IBM 7090 and 7094 computer systems, was retained for the earliest System/360 systems as a count key data device, and was discontinued in 1965. The 7320 is a vertically mounted head-per-track device with 449 tracks, 400 data tracks, 40 alternate tracks, and 9 clock/format tracks. The rotational speed is 3,490 rpm, so the average rotational delay is 8.6 milliseconds.{{cite manual
| title = IBM 7320 Drum Storage
| year = 1962
| url = http://bitsavers.org/pdf/ibm/7090/G22-6717_7320_7631_1962.pdf
| series = 7090/7094 Data Processing Systems
| publisher = IBM Corporation
}}
Attachment to a 709x system is through an IBM 7909 Data Channel and an IBM 7631 File Control unit, which can attach up to five random-access storage units, a mix of 7320 1301, and 1302 DASD. One or two 7631 controllers can attach to a computer system, but the system can still attach only a total of five DASD. When used with a 709x, a track holds 2,796 6-bit characters, and a 7320 unit holds 1,118,400 characters.{{efn|The actual capacity depends on the contents of the format track, but with full track formatting it is 2,796 6-bit characters/track and 1,118,400 characters/unit.}} Data transfer rate is 202,800 characters per second.
The 7320 attaches to a System/360 through a channel and an 2841 Storage Control unit. Each 2841 can attach up to eight 7320 devices. When used with System/360, a track holds 2,081 8-bit bytes, and a 7320 unit holds 878,000 bytes. Data transfer rate is 135,000 bytes per second.{{cite manual
| title = IBM System/360 Component Descriptions - 2841 Storage Control Unit, 2302 Disk Storage, Models 3 and 4, 2311 Disk Storage Drive, 2321 Data Cell Drive, Model 1, 7320 Drum Storage
| id = A26-5988-0
| edition = First
| date =
| chapter = IBM 7320 Drum Storage
| section-url = http://bitsavers.org/pdf/ibm/2841/A26-5988-0_2841_2311_2321_7320_Descr.pdf#page=44
| page = 41
| quote = The drum is divided into 400 data tracks; each track has a read/write head and may contain up to 2,081 bytes of data. The maximum data transfer rate is 135 thousand bytes per second.
| url = http://bitsavers.org/pdf/ibm/2841/A26-5988-0_2841_2311_2321_7320_Descr.pdf
| ref = {{sfnref|IBM 7320}}
| access-date = Dec 6, 2019
| series = Systems Reference Library
| publisher = IBM
}}
The 7320 was superseded by the IBM 2301 in mid-1966.{{Cite book|title=IBM's 360 and Early 370 Systems|last1=Pugh|first1=Emerson W.|last2=Johnson|first2=Lyle R.|last3=Palmer|first3=John H.|publisher=MIT Press|year=1991|isbn=0-262-16123-0|location=|page=[https://archive.org/details/ibms360early370s0000pugh/page/272 272] |url=https://archive.org/details/ibms360early370s0000pugh|url-access=registration|author-link=Emerson Pugh}}{{cite journal
|last1=Office of Naval Research
|journal=Digital Computer Newsletter
|date=October 1964
|volume=16
|issue=4
|title=IBM System 360
|pages=7–8
|url=https://books.google.com/books?id=DR8pjs4SVR4C&pg=RA7-PA8
|publisher = Office of Naval Research - Mathematical Sciences Division
|access-date=Dec 6, 2019
}}
IBM 2301
The IBM 2301 is a magnetic drum storage device introduced in the late 1960s to "provide large capacity, direct access storage for IBM System/360 Models 65, 67, 75, or 85." The vertically mounted drum rotates at around 3,500 revolutions per minute, and has a head-per-track access mechanism and a capacity of 4 MB. The 2301 has 800 physical tracks; four physical tracks make up one logical track which is read or written as a unit. The 200 logical tracks have 20,483 bytes each. The average access time is 8.6 ms, and the data transfer rate is 1,200,000 bytes per second. The 2301 attaches to a System/360 via a selector channel and an IBM 2820 Storage Control Unit, which can control up to four 2301 units.{{cite manual
| title = IBM System/360 Component Descriptions -- 2820 Storage Control and 2301 Drum Storage
| id = A22-6895-2
| pages = 30–31
| edition = Third
| date = September 1968
| section = IBM 2301 Drum Storage
| section-url = http://bitsavers.org/pdf/ibm/2820/A22-6895-2_2820_2301_Component_Descr_Sep69.pdf#page=38
| url = http://bitsavers.org/pdf/ibm/2820/A22-6895-2_2820_2301_Component_Descr_Sep69.pdf
| access-date = April 18, 2021
| ref = {{sfnref|2301}}
| series = Systems Reference Library
| publisher = IBM Corporation
}}
IBM 2303
The IBM 2303 is a magnetic drum storage device with the same physical specifications as the IBM 2301. The difference is that the 2303 reads and writes one physical track at a time, rather than the four in the 2301, reducing the data transfer rate to 312,500 bytes per second. The 2303 attaches to System/360 through a channel and an IBM 2841 Storage Control Unit, which can attach up to two 2303 units.{{cite manual
| title = IBM System/360 Component Descriptions - 2841 and Associated DASD
| id = GA26-5988-7
| date = December 1969
| edition = Eighth
| section = IBM 2303 Drum Storage
| section-url = http://bitsavers.org/pdf/ibm/2841/GA26-5988-7_2841_DASD_Component_Descr_Dec69.pdf#page=77
| pages = 74–76
| quote = Storage capacity: 3.913 million bytes. High speed accessibility: Rotational Delay Only: average 8.6ms. Fast data transfer to the processor: 303,800 bytes per second.
| url = http://bitsavers.org/pdf/ibm/2841/GA26-5988-7_2841_DASD_Component_Descr_Dec69.pdf
| ref = {{sfnref|IBM 2303}}
| access-date = April 17, 2021
| series = Systems Reference Library
| publisher = IBM Corporation
}}
See also
- Drum memory: Drums used as main memory
Notes
{{Notelist}}