Data General SuperNova

The Data General Nova was a popular 16-bit minicomputer built by the United States company Data General starting in 1969. The Nova packed enough power to do most simple computing tasks and was packaged into a single rack mount case. The Nova became hugely popular in science labs around the world, and eventually 50,000 would be sold. The Nova was followed by the Eclipse, which was similar in most ways but added virtual memory support and other features required by modern operating systems. Data General Super Nova. ... Data General Super Nova. ... In computer science, 16-bit is an adjective used to describe integers that are at most two bytes wide, or to describe CPU architectures based on registers, address buses, or data buses of that size. ... Minicomputer (colloquially, mini) is a largely obsolete term for a class of multi-user computers which make up the middle range of the computing spectrum, in between the largest multi-user systems (traditionally, mainframe computers) and the smallest single-user systems (microcomputers or personal computers). ... Data General was one of the first minicomputer firms from the late 1960s. ... Equipment mounted in several 19-inch racks A 19-inch rack is a standardized (EIA 310-D, IEC 60297 DIN 41494 SC48D) system for mounting various electronic modules in a stack, or rack. ... The Data General Eclipse line of computers by Data General were 16-bit minicomputers released in early 1974. ... The memory pages of the virtual address space seen by the process, may reside non-contiguously in primary, or even secondary storage. ... An operating system is a special computer program that manages the relationship between application software, the wide variety of hardware that makes up a computer system, and the user of the system. ...

History

deCastro and the Nova's origin

Edson deCastro was the Product Manager at Digital Equipment (DEC) of their pioneering PDP-8, a 12-bit computer generally considered by most to be the first true minicomputer. DeCastro was convinced, however, that it was possible to improve upon the PDP-8 by building a 16-bit minicomputer on a single board. Ken Olsen was not supportive of this project, so deCastro left DEC along with another hardware engineer, Richard Sogge, and a software engineer, Henry Burkhardt III, to found Data General (DG) in 1968. The fourth founder, Herbert Richman, had been a salesman for Fairchild Semiconductor and knew the others through his contacts with Digital Equipment. Digital Equipment Corporation was a pioneering company in the American computer industry. ... A PDP-8 on display at the Smithsonians National Museum of American History in Washington, D.C.. This example is from the first generation of PDP-8s, built with discrete transistors and later known as the Straight 8. ... Ken Olsen calling UNIX snake oil Kenneth H. Olsen (born on February 20, 1926) is an American engineer who cofounded Digital Equipment Corporation in 1957 with colleague Harlan Anderson. ... Henry Burkhardt III (1945-2000) was born in Ann Arbor, Michigan, grew up in South Hadley, Massachusetts, and was schooled there. ... 1968 (MCMLXVIII) was a leap year starting on Monday (the link is to a full 1968 calendar). ... Fairchild Semiconductor introduced the first commercially available integrated circuit (although at almost the same time as one from Texas Instruments), and would go on to become one of the major players in the evolution of Silicon Valley in the 1960s. ...

The next year DG released the 16-bit Nova at a base price of US$3,995, advertising it as «the best small computer in the world». The basic model was not very useful "out of the box", and adding RAM in the form of core memory typically brought the price up to $7,995. A 16×16 cm area core memory plane of 128×128 bits, i. ...

The Nova's biggest competition was from the newly-born DEC PDP-11 computer series, and to a lesser extent the venerable DEC PDP-8 systems. It has been said that the Nova was pretty crude compared to its competitors; but it was quite effective and very fast for its day, at least at its low-cost end of the market. Dennis Ritchie and Ken Thompson at a PDP-11 The PDP-11 was a 16-bit minicomputer sold by Digital Equipment Corp. ... A PDP-8 on display at the Smithsonians National Museum of American History in Washington, D.C.. This example is from the first generation of PDP-8s, built with discrete transistors and later known as the Straight 8. ...

Besides offering 16 bits compared to the 12 bits of the PDP-8, another big innovation of the Nova was in packaging. The original Nova CPU was built on only two large 15×15 inch (38×38 cm) printed circuit boards, which could be run off on an assembly line with no manual wiring required. This greatly reduced costs over the rival PDP-8 and PDP-8/I, which consisted of many smaller boards that had to be wired together. The larger-board construction also made the Nova more reliable, which made it especially attractive for industrial or lab settings. A PDP-8 on display at the Smithsonians National Museum of American History in Washington, D.C.. This example is from the first generation of PDP-8s, built with discrete transistors and later known as the Straight 8. ... Close-up photo of one side of a motherboard PCB, showing conductive traces, vias and solder points for through-hole components on the opposite side. ...

A further improvement on the Nova design followed the next year, the SuperNOVA. The SuperNOVA included a number of improvements that dramatically improved performance over the original. This included the use of ROM for library software that could be run much faster than the same code in the normal core memory, due to the latter's need to be written immediately after being read. Additionally the system included a new set of core with an 800 ns cycle time, faster than the original's 1200 ns version. Finally the SuperNOVA also replaced the earlier model's 4-bits-at-a-time math unit with a new 16-bit parallel version, speeding math by up to four times. Read-only memory (ROM) is a class of storage media used in computers and other electronic devices. ... A 16×16 cm area core memory plane of 128×128 bits, i. ...

Soon after the introduction of the SuperNOVA, another version featuring semiconductor memory in place of core was introduced, the SuperNOVA SC. The much higher performance memory allowed the CPU, which was synchronous with memory, to be further increased in speed to run at a 300 nanosecond cycle time (3.3 MHz), which made it the fastest minicomputer for over a decade following its introduction. To help compare orders of magnitude of different times this page lists times between 10−9 seconds and 10−8 seconds (1 nanosecond and 10 nanoseconds) See also times of other orders of magnitude. ...

Later versions

Further improvements in the line followed in 1970/1 with a pair of machines that replaced the Nova/SuperNOVA, the Nova 1200 and Nova 800 series. The 1200 used the original's slower 1200ns core while the 800 featured the SuperNOVA's 800ns core, explaining the somewhat confusing naming where the lower number represents the faster machine. Like the earlier models, the 1200 used a 4-bit math unit while the 800 used the SuperNOVA's 16-bit unit. Both models were offered in a variety of cases, the 1200 with seven slots, the 1210 with four and the 1220 with fourteen. The 840, first offered in 1973, also included a new paged memory system allowing for up to 17-bit addresses. An index offset the base address into the larger 128 kWord memory. Actually installing this much memory required considerable space, the 840 shipped in a large 14-slot case.

The next version was the 'Nova 2, with the first versions shipping in 1973. The Nova 2 was essentially a simplified version of the earlier machines as increasing chip densities allowed the CPU to be reduced in size. While the SuperNOVA used three 15"x15" boards to implement the CPU and it's memory, the Nova 2 fit all of this onto a single board. ROM was used to store the boot code, which was then copied into core when the "program load" switch was flipped. Versions were available with four, seven and ten slots.

Data General Nova 3

The Nova 3 of 1975 added two more registers, used to control access to a built-in stack. The processor was also re-implemented using four 4-bit LSI chips in place of the earlier TTL components, further lowering the cost of the system. The Nova 3 was offered in three and twelve slot versions. Image File history File links Download high resolution version (1024x683, 96 KB) Summary Photograph taken by me. ... Image File history File links Download high resolution version (1024x683, 96 KB) Summary Photograph taken by me. ...

It appears that Data General originally intended the Nova 3 to be the last of it's line, planning to replace the Nova with the later Eclipse machines. However continued demand led to a Nova 4 machine, this time based on four AMD 2901 bit-slice ALUs. This machine was designed from the start to be both the Nova 4 and the Eclipse S/140, with different microcode for each. A floating-point co-processor was also available, taking up a separate slot. An additional option allowed for memory mapping, allowing programs to access up to 128 kwords of memory using bank switching. Unlike the earlier machines, the Nova 4 did not include a front panel console (switches and lights) and instead relied on the terminal to emulate a console when needed. Am2900 is a family integrated circuits (ICs) created in 1975 by Advanced Micro Devices (AMD). ... ALU redirects here. ... A microprogram is a program consisting of microcode that controls the different parts of a computers central processing unit (CPU). ... Bank switching (also known as paging, but only loosely related to the ordinary meaning of this term in computing) was a technique common in 8-bit microcomputer systems, to increase the amount of addressable RAM and ROM without extending the address bus. ... The term Terminal can be used in several way and includes various topics: Usually terminal means forming or pertaining to an end. ...

microNOVA

Data General also produced a series of single-chip implementations of the Nova processor as the microNOVA. Changes to the bus architecture limited speed dramatically, to the point where it was about one-half the speed of the original Nova. The original microNOVA with the "mN601" processor shipped in 1977. It was followed by the microNOVA MP/100 in 1979, which reduced the CPU to a single VLSI chip, the mN602. A larger version was also offered as the microNOVA MP/200, shipping the same year. Very-large-scale integration (VLSI) of systems of transistor-based circuits into integrated circuits on a single chip first occurred in the 1980s as part of the semiconductor and communication technologies that were being developed. ...

The microNOVA was later re-packaged in a PC-style case with two floppy disks as the Enterprise. Enterprise shipped in 1981, running RDOS, but the introduction of the IBM PC the same year made most other machines disappear under the radar. A floppy disk is a data storage device that is composed of a ring of thin, flexible (i. ... RDOS, or the Real-time Disk Operating System, was a real-time operating system released in 1972 for the popular Data General Nova and Data General Eclipse minicomputers. ... IBM PC (IBM 5150) with keyboard and green screen monochrome monitor (IBM 5151), running MS-DOS 5. ...

Nova's legacy

The Nova influenced the design of both the Xerox Alto (1973) and Apple I (1976) computers. Its external design has been reported to be the direct inspiration for the front panel of the MITS Altair (1975) microcomputer. A Xerox Alto Computer System The Xerox Alto, developed at Xerox PARC in 1973, was the first personal computer and the first computer to use the desktop metaphor and graphical user interface (GUI). ... 1973 (MCMLXXIII) was a common year starting on Monday (the link is to a full 1973 calendar). ... The Apple I was an early personal computer, and the first to combine a keyboard with a microprocessor and a connection to a monitor. ... 1976 (MCMLXXVI) was a leap year starting on Thursday (the link is to a full 1976 calendar). ... Altair 8800 The MITS Altair 8800 was a microcomputer design from 1975, based on the Intel 8080A CPU. Sold as a kit through Popular Electronics magazine, the designers intended to sell only a few hundred to hobbyists, and were surprised when they sold over ten times that many in the... 1975 (MCMLXXV) was a common year starting on Wednesday (the link is to a full 1975 calendar). ...

Data General followed up on the success of the original Nova with a series of faster designs. The Eclipse family of systems was later introduced with an extended upwardly compatible instruction set, and the MV-series further extended the Eclipse into a 32-bit architecture to compete with the DEC VAX. The development of the MV-series was documented in Tracy Kidder's popular 1981 book, The Soul of a New Machine. Data General itself would later evolve into a vendor of Intel processor-based servers and storage arrays, eventually being purchased by EMC. VAX is a 32-bit computing architecture that supports an orthogonal instruction set (machine language) and virtual addressing (i. ... The Soul of a New Machine is a non-fiction book, authored by Tracy Kidder. ... EMC is a TLA that may stand for: electric membership corporation electromagnetic compatibility Electro-Motive Corporation, the predecessor to General Motors Electro-Motive Division EMC Corporation European Marketing Confederation European Muon Collaboration Evergreen Marine Corporation This page concerning a three-letter acronym or abbreviation is a disambiguation page — a navigational...

As of 2004 there are still 16-bit Novas and Eclipses running in a variety of applications worldwide. There is a diverse but ardent group of people worldwide who restore and preserve legacy 16-bit Data General systems. 2004 is a leap year starting on Thursday of the Gregorian calendar. ... The Data General Eclipse line of computers by Data General were 16-bit minicomputers released in early 1974. ...

Technical description

Processor design

Nova 3 PCB

The Nova had four 16-bit accumulator registers, of which two (2 and 3) could be used as index registers. There was a 15-bit program counter and a single-bit carry register. As with the PDP-8, current + zero page addressing was central. Image File history File links Download high resolution version (1024x683, 253 KB) Summary Photograph taken by me. ... Image File history File links Download high resolution version (1024x683, 253 KB) Summary Photograph taken by me. ... In a CPU, an accumulator is a register in which intermediate results are stored. ... An index register in a computer CPU is a processor register used for modifying operand addresses during the run of a program, typically for doing vector/array operations. ... The program counter (also called the instruction pointer in some computers) is a register in a computer processor which indicates where the computer is in its instruction sequence. ... The zero page is the memory address page at the absolute beginning of a computers address space (the lowermost page, covered by the memory address range 0 . ...

The earliest models of the Nova processed math serially in 4-bit packets. A year after its introduction the processor was upgraded to use a full 16-bit parallel math unit, this design being referred to as the SuperNova. Future versions of the system added a stack unit and hardware multiply/divide.

The Nova 4 / Eclipse S/140 was based on four AMD 2901 bit-slice ALUs, with microcode in read-only memory, and was the first Nova designed for DRAM main memory only, without provision for magnetic core memory. Am2900 is a family integrated circuits (ICs) created in 1975 by Advanced Micro Devices (AMD). ... ALU redirects here. ... A microprogram is a program consisting of microcode that controls the different parts of a computers central processing unit (CPU). ... Read-only memory (ROM) is a class of storage media used in computers and other electronic devices. ... Dram can mean several things: for the imperial unit of volume see dram (volume) for the imperial unit of weight or mass see avoirdupois and apothecaries system of mass for the Armenian monetary unit see dram (currency) DRAM is a type of RAM and unlike dram is spelled in all... A 16×16 cm area core memory plane of 128×128 bits, i. ...

Memory and I/O

The first models were available with 4K words of magnetic core memory as an option, one that practically everyone had to buy, bringing the system cost up to $7,995. Even here DG managed to innovate, packing several planes of very small core and the corresponding support electronics onto a single standard 15 x 15 inch board. Up to 32K of such core RAM could be supported in one external expansion box. Semiconductor ROM was already available at the time, and RAM-less systems (i.e. with ROM only) became popular in many industrial settings. The original Nova machines ran at approximately 0.2 MHz, but its SuperNova was designed to run at up to 3 MHz when used with special semiconductor main memory. The eleventh letter of the Latin alphabet, K, or k comes from the Greek Κ or κ (Kappa) developed from the Semitic Kap, symbol for an open hand. ... In computing, word is a term for the natural unit of data used by a particular computer design. ... A 16×16 cm area core memory plane of 128×128 bits, i. ... Different types of RAM. From top to bottom: DIP, SIPP, SIMM 30 pin, SIMM 72 pin, DIMM, RIMM RAM redirects here. ... A semiconductor is a material with an electrical conductivity that is intermediate between that of an insulator and a conductor. ... Read-only memory (ROM) is a class of storage media used in computers and other electronic devices. ... MegaHertz (MHz) is the name given to one million (106) Hertz, a measure of frequency. ...

The standardized backplane and I/O signals created a simple, efficient I/O design that made interfacing programmed I/O and Data Channel devices to the Nova simple compared to competitive machines. In addition to its dedicated I/O bus structure, the Nova backplane had wirewrap pins that could be used for non-standard connectors or other special purposes. A backplane is a circuit board (usually a printed circuit board) that connects several connectors in parallel to each other, so that each pin of each connector is linked to the same relative pin of all the other connectors, forming a computer bus. ... Input/output, or I/O, is the collection of interfaces that different functional units (sub-systems) of an information processing system use to communicate with each other, or to the signals (information) sent through those interfaces. ...

Programming model

The instruction format could be broadly categorized into one of three functions: 1) register-to-register manipulation, 2) memory reference, and 3) input/output. Each instruction was contained in one word. The register-to-register manipulation was almost RISC-like in its bit-efficiency; and an instruction that manipulated register data could also perform tests, shifts and even elect to discard the result. Hardware options included an integer multiply and divide unit, a floating-point unit (single and double precision), and memory management. An instruction set, or instruction set architecture (ISA), describes the aspects of a computer architecture visible to a programmer, including the native datatypes, instructions, registers, addressing modes, memory architecture, interrupt and exception handling, and external I/O (if any). ... Reduced Instruction Set Computer (RISC), is a microprocessor CPU design philosophy that favors a smaller and simpler set of instructions that all take about the same amount of time to execute. ... A floating point unit (FPU) is a part of a CPU specially designed to carry out operations on floating point numbers. ... Memory management is the act of managing computer memory. ...

Data General software on punched paper tape

Data General developed a wide range languages for the Nova computers running under a range of consistent operating systems. FORTRAN IV, ALGOL, Extended BASIC, Data General Business Basic, Interactive COBOL, and several assemblers were available from Data General. Third party vendors and the user community expanded the offerings with Forth, Lisp, BCPL, C, Algol, and other proprietary versions COBOL and BASIC. Image File history File links Download high resolution version (1024x683, 104 KB) Summary Photograph taken by me. ... Image File history File links Download high resolution version (1024x683, 104 KB) Summary Photograph taken by me. ... Fortran (also FORTRAN) is a statically typed, compiled, programming language originally developed in the 1950s and still heavily used for scientific computing and numerical computation half a century later. ... ALGOL (short for ALGOrithmic Language) is a family of imperative computer programming languages originally developed in the mid 1950s which became the de facto standard way to report algorithms in print for almost the next 30 years. ... BASIC (Beginners All-purpose Symbolic Instruction Code) is a family of high-level programming languages. ... Data General Business Basic was a BASIC interpreter (based on MAI Basic Fours version) developed by Data General for their Nova minicomputer in the 1970s, and later ported to the Data General Eclipse MV and AViiON computers. ... COBOL is a third-generation programming language. ... Forth is a procedural, stack-oriented, reflective programming language and programming environment. ... Lisp is a family of computer programming languages with a long history and a distinctive fully-parenthesized syntax. ... BCPL (Basic Combined Programming Language) is a computer programming language that was designed by Martin Richards of the University of Cambridge in 1966; it was originally intended for use in writing compilers for other languages. ... The C Programming Language, Brian Kernighan and Dennis Ritchie, the original edition that served for many years as an informal specification of the language The C programming language is a standardized imperative computer programming language developed in the early 1970s by Dennis Ritchie for use on the Unix operating system. ... ALGOL (short for ALGOrithmic Language) is a family of imperative computer programming languages originally developed in the mid 1950s which became the de facto standard way to report algorithms in print for almost the next 30 years. ... COBOL is a third-generation programming language. ... BASIC (Beginners All-purpose Symbolic Instruction Code) is a family of high-level programming languages. ...

Assembly language examples

Hello world program

This is a minimal programming example in Nova assembly language. It is designed to run under RDOS and prints the string "Hello, world." on the console. RDOS, or the Real-time Disk Operating System, was a real-time operating system released in 1972 for the popular Data General Nova and Data General Eclipse minicomputers. ... To meet Wikipedias quality standards, this article or section may require cleanup. ...

 ; a "hello, world" program for Nova running RDOS, by Toby Thain ; uses PCHAR system call .titl hello .nrel .ent start start: dochar: lda 0,@pmsg ; load ac0 with next character, mov# 0,0,snr ; test ac0; skip if nonzero (don't load result) jmp done .systm .pchar ; print first jmp er ; skipped if OK movs 0,0 ; swap bytes .systm .pchar ; print second jmp er ; skipped if OK isz pmsg ; point to next character jmp dochar ; go around again done: .systm ; normal exit .rtn er: .systm ; error exit .ertn halt pmsg: .+1 ; pointer to first character of string ; note bytes are packed right-to-left by default .txt /Hello, world.<15><12>/ ; that's CR LF 0 ; flag word to end string .end start 

16-bit multiplication

Basic models of the Nova came without built-in hardware multiply and divide capability, to keep prices competitive. The following routine multiplies two 16-bit words to produce a 16-bit word result (overflow is ignored). It demonstrates combined use of ALU op, shift, and test (skip). Note that when this routine is called by jsr, AC3 holds the return address. This is used by the return instruction jmp 0,3. An idiomatic way to clear an accumulator is sub 0,0. Other single instructions can be arranged to load a specific set of useful constants (e.g. -2, -1, or +1).

 mpy: ; multiply AC0 <- AC1 * AC2, by Toby Thain sub 0,0 ; clear result mbit: movzr 1,1,szc ; shift multiplier, test lsb add 2,0 ; 1: add multiplicand movzl 2,2,szr ; shift and test for zero jmp mbit ; not zero, do another bit jmp 0,3 ; return 

Binary print accumulator

The following routine prints the value of AC1 as a 16 digit binary number, on the RDOS console. It reveals further quirks of the Nova instruction set. For instance, there is no instruction to load an arbitrary "immediate" value into an accumulator (although memory reference instructions do encode such a value to form an effective address). Accumulators must generally be loaded from initialised memory locations (e.g. n16). Other contemporary machines such as the PDP-11, and practically all modern architectures, allow for immediate loads, although many such as ARM restrict the range of values that can be loaded immediately. The binary or base-two numeral system is a system for representing numbers in which a radix of two is used; that is, each digit in a binary numeral may have either of two different values. ... Dennis Ritchie and Ken Thompson at a PDP-11 The PDP-11 was a 16-bit minicomputer sold by Digital Equipment Corp. ... The ARM architecture (originally the Acorn RISC Machine) is a 32-bit RISC processor architecture that is widely used in a number of applications. ...

Because AC3 is not preserved by the RDOS .systm call, a temporary location is needed to preserve the return address. (For a recursive or otherwise re-entrant routine, the stack must be used instead.) The return instruction becomes jmp @ retrn which exploits the Nova's indirect addressing mode to load the return PC.

The constant definitions at the end show two assembler features: the assembler radix is octal by default (20 = sixteen), and character constants could be encoded as e.g. "0. The octal numeral system is the base-8 number system, and uses the digits 0 to 7. ...

 pbin: ; print AC1 on console as 16 binary digits, by Toby Thain sta 3,retrn ; save return addr lda 2,n16 ; set up bit counter loop: lda 0,chr0 ; load ASCII '0' movzl 1,1,szc ; get next bit in carry inc 0,0 ; bump to '1' .systm .pchar ; AC0-2 preserved jmp err ; if error inc 2,2,szr ; bump counter jmp loop ; loop again if not zero lda 0,spc ; output a space .systm .pchar jmp err ; if error jmp @ retrn spc: " ;that's a space chr0: "0 n16: -20 retrn: 0 

Emulating a Data General Nova

Nova assembly language programs can be run under Bob Supnik's SIMH emulator, in RDOS. Of the above examples, only Hello, world is a complete program. It includes the necessary directives for a successful assembly and generation of a runnable program. SIMH is a highly portable, multi-system emulator which runs on Windows, Linux, Mac OS X, FreeBSD, OpenBSD, NetBSD, OpenVMS, and other operating systems. ...

Stepwise instructions

Start the Nova emulation and boot RDOS following the instructions under "Nova and Eclipse RDOS" in the file src/simh_swre.txt of the simh distribution. After booting, RDOS' command prompt, R, should appear on the screen.

• Before the first assembly on a newly setup RDOS system, the macro assembler's default symbol definitions need to be configured using the following command: mac/s nbid osid nsid paru
• Create the assembly source file under RDOS: xfer/a $tti test.sr (the xfer command will accept input at the console and copy it to a disk file named test.sr; after entering the command, copy and paste (or type in) a complete assembly language program, and finish with Control-Z).
• Next, run the macro assembler on test.sr to create the object file test.rb: mac/l test (the /l [slash-ell] option enables the listing file test.ls, which can be copied to the console using the command type test.ls).
• The relocatable loader, rldr, takes the object file and creates the executable test.sv : rldr test
• To run the program, type test

Before going further with serious experimentation, it can be convenient to check one's programs at the PC using a suitable cross-assembler, such as the portable PDP-8/DG Nova cross-assembler listed in the External links section, before attempting execution in the RDOS environment.

RDOS hints

• To have a directory listing of all files with basename test, type list test.- (note the hyphen, RDOS' wildcard character)
• Delete files with delete (this might be needed because xfer won't replace an existing file)
• A running program can usually be interrupted with Control-A
• To exit RDOS, type release %mdir%
• Quit simh at its prompt with q

In playing card terms, a wild card is a card that can be assigned any value its holder desires. ...

External links

• Bob Supnik's SimH project – Includes a basic Nova emulator in a user-modifiable package
• SimuLogic's website – Attempts to archive everything DG plus provide free and commercial products
• A portable PDP-8 and DG Nova cross-assembler