Computer history: The Control Data 4380

CDC 4380 (MIPS 3840)

The Control Data 4000-series systems were CDC enhanced versions of MIPS systems (later acquired by SGI). The 4000-series ran under EP/IX, a UNIX System V variant. The system also had the UNIX BSD 4.3 variant ‘on-board’. As systems programmers at TNO-FEL also had to deal with the CONVEX, UNIX BSD was used often as the primary ‘command and library set’ causing the EP/IX special enhanced UNIX code sometimes to fail.

CDC 4000 series block diagram
CDC 4000 series block diagram


  • 20 MIPS of processing power from a 25 MHz R3000 RISC CPU
  • 16.5 SPECmarks of performance on a balanced set of CPU-intensive large applications
  • 3.9 DP Linpack MFLOPS FORTRAN (6.4 SP) for technical computing
  • 47,400 Dhrystones/s and 14,100 DP Whetstones/s for balanced speed
  • Fast system response for Ethernet devices and for database management
  • 20 MB/s data I/O speed, standard block mode VME bus controllers
  • 100 MB per second CPU-memory bus


  • 32 MB to 128 MB main memory for large programs and multiple users
  • Thirteen VME slots for a large complement of high-performance controllers
  • Support for multiple disks, Ethernet, tape, and serial I/O controllers
  • Direct connections for up to 64 serial lines, unlimited indirect serial lines
  • Two expansion cabinets with ten disks each for additional SMD disk capacity up to 15.7 GB
  • Optional backup storage of up to 2 GB on helical scan technology 8 mm cartridges


  • Binary-compatible with the complete line of Control Data 4000 Series computers
  • SVID-compliant UNIX operating system, BSD and System V converged
  • Suite of high-performance optimizing compilers, including C, FORTRAN, Pascal, Cobol, Ada, and PL/1
  • Networking standards such as TCP/IP and Network File System (NFS)
  • RISCwindows, an implementation of the standard X Windows System combined with OSF Motif
  • Extensive development tools, from Control Data and third-party vendors
  • Wide-range of third-party application software available

The 4380 computer was designed with second-generation RISC technology to maximise its performance using CMOS processors with low-cost TTL electronics and high-performance I/O techniques. It delivered on these performance and cost objectives. The RISC technology foundation for the 4380 systems included robust optimising compilers that handled large complex programs and a tuned port of UNIX. These were combined with advanced VLSI semiconductor technology in the CPU and FPU components and complemented with a host of third-party software. In the 4380, the RISC hardware and software technologies were combined to provide a functional, affordable, very high-performance computer system.

System Packaging

The packaging for the 4380 computer was designed for a computer room environment. Base system configurations were contained in one cabinet that is 159cm H x 61 cm W x 93 cm D). Disk drives and power supplies were located in the lower portion of the system cabinet, the card cage for the processor and I/O controllers in the middle portion, and the magnetic tape drive in the upper portion. Cabling and I/O connections were accessible at the rear. The cabinet was rack width (19″) internal to accommodate industry standard peripherals and system options. Where expansion disks and multiple magnetic tape drives were required, one or more expansion cabinets could be used.

Compute Power

The (then) advanced computation speed of 4380 systems was based on the MIPS second generation R3000 CPU and the companion R3010 Floating Point Unit. These processing units were complemented by large high-speed caches of 64 KB each for instructions and data, by sophisticated read/write buffers for minimizing memory access overhead, and by a fast (100 MB/s) memory system that used new instructions streaming and data block refill techniques.

Processing power is over 20 sustained MIPS, 47,400 Dhrystones, 14, 100 Whetstones DP, and 3.9 MFLOPS Linpack DP FORTRAN. This balanced compute power was applicable to both integer and floating point intensive jobs.

I/O Power

Since the high bandwidth between CPU and memory was provided by a separate private memory bus, the full 32-bit VME bus facility was available for I/O transfers. The 4380 used intelligent, Direct Memory Access type block mode VME controllers for disks and Ethernet ports. These I/O operations normally are most critical to system throughput and user responsiveness. The VME I/O bus in the 4380 achieved data transfer speeds of 20 MB/s for block mode controllers.

Systems Software

The software foundation for 4380 Computers was the UNIX operating system, which was tuned for maximum performance in demanding applications. It included communications protocols for Ethernet networking, the Berkeley Fast File System, and NFS for transparent file sharing between systems.
The operating system also included system and user interface utilities of the converged System V and BSD versions of UNIX to support the largest set of UNIX application programs.

In addition to the C language, the 4380 computers supported FORTRAN with VMS extensions, as well as Micro Focus Cobol, Pascal, Ada, and PL/l. Language compilers included multilevel optimizations.

EP/IX = Enhanced Performance Implementation of UNIX; originally branded as ‘CLASSIX’ until that name turned out to be registered by someone else.