Massbus
The Massbus is a high-performance computer input/output bus designed in the 1970s by Digital Equipment Corporation (DEC). The architecture development was sponsored by Gordon Bell and John Levy was the principal architect.
The bus was used by Digital to interconnect its highest-performance computers with
A business objective was to provide a subsystem entry price well below that of IBM storage subsystems which used large and expensive controllers unique to each storage technology and processor architecture and were optimized for connecting large numbers of storage devices.
The first Massbus device was the RP04, based on
Logical implementation
The bus is logically implemented as two separate sections:
- An asynchronous control bus used to access memory-mapped I/O registers in the individual storage devices,[1]: 8.0 and
- A high-speed, synchronous data bus that is used to carry the actual data transfers between the storage devices and the host bus adapter.[1]: 8.0 The data bus is 18 bits wide plus parity.[1]: 34.0
Massbus peripherals
Disk
- RP04 88 MB Sperry Univac Information Storage Systems pack-loaded (removable) disk drive[2]
- RP05/RP06 100/200 MB Memorex 677-51/677-01 pack-loaded (removable) disk drive[3][4]
The RP04
Tape
- TU45 9 track, capable of 800 BPI and 1600 BPI; 120,000 bytes/second[7]
- TU78/TA78 6250 GCR[10][11][12] The 1600/6250 BPI TU78 uses DEC's Massbus, whereas the TA78 uses the HSC50 controller.[13]
Massbus CPU interfaces
References
- ^ a b c d "Massbus Specification" (PDF). DEC STD 159.
- ^ a b RP04 Disk Drive Installation Manual (PDF) (1st ed.). Digital Equipment Corporation. March 1975. p. 1-1. EK-RP04-IN-001.
The RP04 (Figure 1-2) consists of a 733 DEC Disk Storage Drive (manufactured by Information Storage Systems) and a Device Control Logic (DCL) unit (Figure 1-3) (manufactured by Digital Equipment Corporation).
- ^ "RP06 disk drive". Computer History Museum.
- ^ "RP05/RP06 disk drive installation manual" (PDF). Digital Equipment Corporation. EK-RP056-IN-001.
- ^ "The DEC RP04 Disk Drive".
- ^ "The DEC RP06 Disk Drive".
- ^ a b EK-DEC20-SP-002 DECSYSTEM-20 Site Preparation Guide.
- ^ "DECsystem-10 Technical Summary".
- ^ RM MASSBUS Adapter Technical Description Manual (PDF). Digital Equipment Corporation. October 1980. p. IV.
- ^ top density
- ^ "TA78 Magnetic Tape Drive Service Manual" (PDF). Digital Equipment Corporation. 1984. EK-0TA78-SV-001.
- ^ "DIGITAL TU78 Reel-to-Reel Tape Drive: Overview".
- ^ Storage Systems: TA78 & TU78. Digital Equipment Corporation.
ORDER CODE ED-23908-18
- ISBN 0-932376-00-2.
- ^ "RH750 Massbus Adapter Technical Description".