DEC Professional (computer)
Encyclopedia
The Professional 325 and Professional 350 (PRO-350) were PDP-11
compatible microcomputer
s introduced in 1982 by Digital Equipment Corporation
(DEC) as high-end competitors to the IBM PC
. Like the cosmetically similar Rainbow-100 and DECmate-II (also introduced at that time), they used the LK201
keyboard and used 400kB single-sided quad-density floppy disk
drives (known as RX50), and offered a choice of color or monochrome monitors.
For DEC, none of the three would be favorably received , and the industry instead standardized on Intel 8088
-based IBM PC compatible
s which were all binary program compatible with each other. In some ways, the PDP-11 microprocessors were technically superior to the Intel-based chips. While the 8088 was restricted to 1MB of memory because of its 20-bit address bus, DEC microprocessors were capable of accessing 4MB with their 22-bit addressing (although direct addressing of memory was limited in both approaches to 64KB segments, limiting the size of individual code and data objects). But other factors would weigh more heavily in the competition, including Digital's corporate culture and business model, which were ill suited to the rapidly developing consumer market for computers.
Further, although the PDP-11 was a very successful minicomputer, it lacked a wide base of affordable small business software. By comparison, many existing CP/M
applications (see the Rainbow 100
) were easily ported to the similar 8086/8088 chips and MS-DOS
operating system. Porting existing PDP-11 software to the PRO was complicated by design decisions that rendered it partially incompatible with its parent product line. Industry critics observed that this incompatibility appeared at least in part deliberate, as DEC belatedly sought to "protect" its more-profitable mainstream PDP11s from price competition with lower-priced PCs.
The PRO was never widely accepted as an office personal computer, nor as a scientific workstation, where the market was also headed to Intel 8086
, or alternately to Motorola 68000
-based computers. The failure of DEC to gain a significant foothold in the high-volume PC market would be the beginning of the end of the computer hardware industry in New England, as nearly all computer companies located there were focused on minicomputer
s, from DEC to Data General
, Wang
, Prime
, Computervision
and Honeywell
.
(as used in LSI-11/23 systems) to create a relatively compact single-board PDP-11 with up to 6 expansion slots of proprietary CTI (Computing Terminal Interconnect) bus using 90- pin ZIF connectors. The PRO family used RX50 floppies for storage; the PRO-325 had only floppies, the 350 and 380 also included an internal hard drive. Mainline PDP11s generally used separate serial terminals as console and display devices; the PRO family used in-built bit-mapped graphics to drive their combined console and display. All other I/O devices in the PRO family were also different (in most cases, radically different) from their counterparts on other PDP-11 models. For example, while the internal bus supported direct memory access (DMA), none of the available I/O devices used this feature. The interrupt system was implemented using Intel PC chips of the time, which again made it very different from the PDP-11 standard. For all these reasons, support of the PRO family required extensive modifications to the previous operating system software, and the PRO could not run standard PDP-11 software without modification.
The default PRO-3xx operating system was DEC's Professional Operating System or P/OS, which was a modified version of RSX-11M
with a menu-driven core user interface. Industry critics complained that this user interface was awkward, slow, and inflexible, offering few advantages over the command-line based MS-DOS user interface that was coming into widespread use.
Other available operating systems included DEC RT-11
, VenturCom Venix
, and 2.9BSD Unix
.
Later, the Professional 380 (PRO-380) was introduced using the much faster J11
chip set (as used in 11/73
systems). A PRO-380 with the Real-Time Interface option was later used as the console on high-end VAX
-8800 family systems.
PDP-11
The PDP-11 was a series of 16-bit minicomputers sold by Digital Equipment Corporation from 1970 into the 1990s, one of a succession of products in the PDP series. The PDP-11 replaced the PDP-8 in many real-time applications, although both product lines lived in parallel for more than 10 years...
compatible microcomputer
Microcomputer
A microcomputer is a computer with a microprocessor as its central processing unit. They are physically small compared to mainframe and minicomputers...
s introduced in 1982 by Digital Equipment Corporation
Digital Equipment Corporation
Digital Equipment Corporation was a major American company in the computer industry and a leading vendor of computer systems, software and peripherals from the 1960s to the 1990s...
(DEC) as high-end competitors to the IBM PC
IBM PC
The IBM Personal Computer, commonly known as the IBM PC, is the original version and progenitor of the IBM PC compatible hardware platform. It is IBM model number 5150, and was introduced on August 12, 1981...
. Like the cosmetically similar Rainbow-100 and DECmate-II (also introduced at that time), they used the LK201
LK201
The LK201 was a detachable computer keyboard introduced by Digital Equipment Corporation of Maynard, Massachusetts in 1982. It was first used by Digital's VT220 ANSI/ASCII terminal and was subsequently used by the Rainbow-100, DECmate-II, and Pro-350 microcomputers and many of Digital's computer...
keyboard and used 400kB single-sided quad-density floppy disk
Floppy disk
A floppy disk is a disk storage medium composed of a disk of thin and flexible magnetic storage medium, sealed in a rectangular plastic carrier lined with fabric that removes dust particles...
drives (known as RX50), and offered a choice of color or monochrome monitors.
For DEC, none of the three would be favorably received , and the industry instead standardized on Intel 8088
Intel 8088
The Intel 8088 microprocessor was a variant of the Intel 8086 and was introduced on July 1, 1979. It had an 8-bit external data bus instead of the 16-bit bus of the 8086. The 16-bit registers and the one megabyte address range were unchanged, however...
-based IBM PC compatible
IBM PC compatible
IBM PC compatible computers are those generally similar to the original IBM PC, XT, and AT. Such computers used to be referred to as PC clones, or IBM clones since they almost exactly duplicated all the significant features of the PC architecture, facilitated by various manufacturers' ability to...
s which were all binary program compatible with each other. In some ways, the PDP-11 microprocessors were technically superior to the Intel-based chips. While the 8088 was restricted to 1MB of memory because of its 20-bit address bus, DEC microprocessors were capable of accessing 4MB with their 22-bit addressing (although direct addressing of memory was limited in both approaches to 64KB segments, limiting the size of individual code and data objects). But other factors would weigh more heavily in the competition, including Digital's corporate culture and business model, which were ill suited to the rapidly developing consumer market for computers.
Further, although the PDP-11 was a very successful minicomputer, it lacked a wide base of affordable small business software. By comparison, many existing CP/M
CP/M
CP/M was a mass-market operating system created for Intel 8080/85 based microcomputers by Gary Kildall of Digital Research, Inc...
applications (see the Rainbow 100
Rainbow 100
The Rainbow 100 was a microcomputer introduced by Digital Equipment Corporation in 1982. This desktop unit had the video-terminal display circuitry from the VT102, a video monitor similar to the VT220 in a dual-CPU box with both Zilog Z80 and Intel 8088 CPUs.The Rainbow 100 was a triple-use...
) were easily ported to the similar 8086/8088 chips and MS-DOS
MS-DOS
MS-DOS is an operating system for x86-based personal computers. It was the most commonly used member of the DOS family of operating systems, and was the main operating system for IBM PC compatible personal computers during the 1980s to the mid 1990s, until it was gradually superseded by operating...
operating system. Porting existing PDP-11 software to the PRO was complicated by design decisions that rendered it partially incompatible with its parent product line. Industry critics observed that this incompatibility appeared at least in part deliberate, as DEC belatedly sought to "protect" its more-profitable mainstream PDP11s from price competition with lower-priced PCs.
The PRO was never widely accepted as an office personal computer, nor as a scientific workstation, where the market was also headed to Intel 8086
Intel 8086
The 8086 is a 16-bit microprocessor chip designed by Intel between early 1976 and mid-1978, when it was released. The 8086 gave rise to the x86 architecture of Intel's future processors...
, or alternately to Motorola 68000
Motorola 68000
The Motorola 68000 is a 16/32-bit CISC microprocessor core designed and marketed by Freescale Semiconductor...
-based computers. The failure of DEC to gain a significant foothold in the high-volume PC market would be the beginning of the end of the computer hardware industry in New England, as nearly all computer companies located there were focused on minicomputer
Minicomputer
A minicomputer is a class of multi-user computers that lies in the middle range of the computing spectrum, in between the largest multi-user systems and the smallest single-user systems...
s, from DEC to Data General
Data General
Data General was one of the first minicomputer firms from the late 1960s. Three of the four founders were former employees of Digital Equipment Corporation. Their first product, the Data General Nova, was a 16-bit minicomputer...
, Wang
Wang Laboratories
Wang Laboratories was a computer company founded in 1951 by Dr. An Wang and Dr. G. Y. Chu. The company was successively headquartered in Cambridge , Tewksbury , and finally in Lowell, Massachusetts . At its peak in the 1980s, Wang Laboratories had annual revenues of $3 billion and employed over...
, Prime
Prime Computer
Prime Computer, Inc. was a Natick, Massachusetts-based producer of minicomputers from 1972 until 1992. The alternative spellings "PR1ME" and "PR1ME Computer" were used as brand names or logos by the company.-Founders:...
, Computervision
Computervision
Computervision, Inc. was an early pioneer in turnkey Computer Aided Design and Manufacturing . Computervision was founded in 1969 by Marty Allen and Philippe Villers, and headquartered in Bedford, Massachusetts, USA. Its early products were built on a Data General Nova platform...
and Honeywell
Honeywell
Honeywell International, Inc. is a major conglomerate company that produces a variety of consumer products, engineering services, and aerospace systems for a wide variety of customers, from private consumers to major corporations and governments....
.
Technical specifications
The PRO-325 and -350 used the F-11 chipsetChipset
A chipset, PC chipset, or chip set refers to a group of integrated circuits, or chips, that are designed to work together. They are usually marketed as a single product.- Computers :...
(as used in LSI-11/23 systems) to create a relatively compact single-board PDP-11 with up to 6 expansion slots of proprietary CTI (Computing Terminal Interconnect) bus using 90- pin ZIF connectors. The PRO family used RX50 floppies for storage; the PRO-325 had only floppies, the 350 and 380 also included an internal hard drive. Mainline PDP11s generally used separate serial terminals as console and display devices; the PRO family used in-built bit-mapped graphics to drive their combined console and display. All other I/O devices in the PRO family were also different (in most cases, radically different) from their counterparts on other PDP-11 models. For example, while the internal bus supported direct memory access (DMA), none of the available I/O devices used this feature. The interrupt system was implemented using Intel PC chips of the time, which again made it very different from the PDP-11 standard. For all these reasons, support of the PRO family required extensive modifications to the previous operating system software, and the PRO could not run standard PDP-11 software without modification.
The default PRO-3xx operating system was DEC's Professional Operating System or P/OS, which was a modified version of RSX-11M
RSX-11
RSX-11 is a family of real-time operating systems mainly for PDP-11 computers created by Digital Equipment Corporation , common in the late 1970s and early 1980s. RSX-11D first appeared on the PDP-11/40 in 1972...
with a menu-driven core user interface. Industry critics complained that this user interface was awkward, slow, and inflexible, offering few advantages over the command-line based MS-DOS user interface that was coming into widespread use.
Other available operating systems included DEC RT-11
RT-11
RT-11 was a small, single-user real-time operating system for the Digital Equipment Corporation PDP-11 family of 16-bit computers...
, VenturCom Venix
Venix
Venix was a version of the Unix operating system developed by VenturCom.Venix 2.0, based on System III, ran on the DEC PRO-350 microcomputer , the DEC Rainbow 100 as well as PCs . It was released in 1984...
, and 2.9BSD Unix
Berkeley Software Distribution
Berkeley Software Distribution is a Unix operating system derivative developed and distributed by the Computer Systems Research Group of the University of California, Berkeley, from 1977 to 1995...
.
Later, the Professional 380 (PRO-380) was introduced using the much faster J11
DEC J-11
The J-11 is a microprocessor chip set that implements the PDP-11 instruction set architecture jointly developed by Digital Equipment Corporation and Harris Semiconductor. It was a high-end chip set designed to integrate the performance and features of the PDP-11/70 onto a handful of chips...
chip set (as used in 11/73
PDP-11/73
The PDP-11/73 was the third generation of the PDP-11 series of 16-bit minicomputers produced by Digital Equipment Corporation to use LSI processors...
systems). A PRO-380 with the Real-Time Interface option was later used as the console on high-end VAX
VAX
VAX was an instruction set architecture developed by Digital Equipment Corporation in the mid-1970s. A 32-bit complex instruction set computer ISA, it was designed to extend or replace DEC's various Programmed Data Processor ISAs...
-8800 family systems.
External links
- Pro 325, 350, 380
- The Observation Deck: UNIX, circa 1984
- The Xhomer, DEC Pro emulator based on the SIMHSIMHSIMH is a highly portable, multi-system emulator which runs on Windows, Linux, Mac OS X, FreeBSD, OpenBSD, NetBSD, OpenVMS, and other operating systems...
/PDP-11.