The Research Machines 380Z (often called the RML 380Z or RM 380Z) was an early
8-bit
In computer architecture, 8-bit Integer (computer science), integers or other Data (computing), data units are those that are 8 bits wide (1 octet (computing), octet). Also, 8-bit central processing unit (CPU) and arithmetic logic unit (ALU) arc ...
microcomputer
A microcomputer is a small, relatively inexpensive computer having a central processing unit (CPU) made out of a microprocessor. The computer also includes memory and input/output (I/O) circuitry together mounted on a printed circuit board (PC ...
produced by
Research Machines
RM Education is the principal division of RM plc, a British company that specialises in providing information technology products and services to educational organisations and establishments. Its key market is UK education including schools, col ...
in
Oxford
Oxford () is a city in England. It is the county town and only city of Oxfordshire. In 2020, its population was estimated at 151,584. It is north-west of London, south-east of Birmingham and north-east of Bristol. The city is home to the ...
,
England
England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...
, from 1977 to 1985.
Description
The 380Z used a
Z80
The Z80 is an 8-bit microprocessor introduced by Zilog as the startup company's first product. The Z80 was conceived by Federico Faggin in late 1974 and developed by him and his 11 employees starting in early 1975. The first working samples were ...
microprocessor
A microprocessor is a computer processor where the data processing logic and control is included on a single integrated circuit, or a small number of integrated circuits. The microprocessor contains the arithmetic, logic, and control circu ...
(hence the name) with up to 56
KB of user
RAM
Ram, ram, or RAM may refer to:
Animals
* A male sheep
* Ram cichlid, a freshwater tropical fish
People
* Ram (given name)
* Ram (surname)
* Ram (director) (Ramsubramaniam), an Indian Tamil film director
* RAM (musician) (born 1974), Dutch
* ...
.
When fitted with an optional
floppy disk
A floppy disk or floppy diskette (casually referred to as a floppy, or a diskette) is an obsolescent type of disk storage composed of a thin and flexible disk of a magnetic storage medium in a square or nearly square plastic enclosure lined w ...
drive the system ran the
CP/M
CP/M, originally standing for Control Program/Monitor and later Control Program for Microcomputers, is a mass-market operating system created in 1974 for Intel 8080/ 85-based microcomputers by Gary Kildall of Digital Research, Inc. Initial ...
operating system
An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs.
Time-sharing operating systems schedule tasks for efficient use of the system and may also in ...
.
The basic system came with a text-only monochrome
video card
A graphics card (also called a video card, display card, graphics adapter, VGA card/VGA, video adapter, display adapter, or mistakenly GPU) is an expansion card which generates a feed of output images to a display device, such as a computer moni ...
, which could be enhanced with a 320×192
high-resolution
Image resolution is the detail an image holds. The term applies to digital images, film images, and other types of images. "Higher resolution" means more image detail.
Image resolution can be measured in various ways. Resolution quantifies how cl ...
graphics board.
Aided by a British government subsidy to schools for half of the price
the 380Z was sold mainly to educational institutions in the United Kingdom, with some also sold to industry. In 1979 a dual 8-inch disk system with 56 KB of memory cost
£3266, and a 16 KB cassette-based system cost £965 (excluding
VAT
A value-added tax (VAT), known in some countries as a goods and services tax (GST), is a type of tax that is assessed incrementally. It is levied on the price of a product or service at each stage of production, distribution, or sale to the en ...
).
Hardware
Architecture
The 380Z was packaged in a large, black,
19-inch rack
A 19-inch rack is a standardized frame or enclosure for mounting multiple electronic equipment modules. Each module has a front panel that is wide. The 19 inch dimension includes the edges or "ears" that protrude from each side of the equ ...
-mount, rectangular metal case containing the power supply, a number of
printed circuit board
A printed circuit board (PCB; also printed wiring board or PWB) is a medium used in Electrical engineering, electrical and electronic engineering to connect electronic components to one another in a controlled manner. It takes the form of a L ...
s and the optional 5¼-inch
floppy disk
A floppy disk or floppy diskette (casually referred to as a floppy, or a diskette) is an obsolescent type of disk storage composed of a thin and flexible disk of a magnetic storage medium in a square or nearly square plastic enclosure lined w ...
drives. The front panel had a pair of strong carrying handles, a keyswitch and a reset button. The keyswitch controlled power and also enabled the reset button. The
keyboard
Keyboard may refer to:
Text input
* Keyboard, part of a typewriter
* Computer keyboard
** Keyboard layout, the software control of computer keyboards and their mapping
** Keyboard technology, computer keyboard hardware and firmware
Music
* Musi ...
was separate and came in a tough metal case.
Early versions were contained in a light blue metal case with a white front and had only a cassette interface or 8-inch
floppy
A floppy disk or floppy diskette (casually referred to as a floppy, or a diskette) is an obsolescent type of disk storage composed of a thin and flexible disk of a magnetic storage medium in a square or nearly square plastic enclosure lined wi ...
drives; only a small number of these were made. An optional 8-bit
ASCII
ASCII ( ), abbreviated from American Standard Code for Information Interchange, is a character encoding standard for electronic communication. ASCII codes represent text in computers, telecommunications equipment, and other devices. Because of ...
paper tape
Five- and eight-hole punched paper tape
Paper tape reader on the Harwell computer with a small piece of five-hole tape connected in a circle – creating a physical program loop
Punched tape or perforated paper tape is a form of data storage ...
punch/reader was also used, as this was a common storage medium at the time - where previous use of a computer had been limited to a
teletype
A teleprinter (teletypewriter, teletype or TTY) is an electromechanical device that can be used to send and receive typed messages through various communications channels, in both point-to-point and point-to-multipoint configurations. Initia ...
machine connected to
mainframe by telephone.
The system used a passive
bus
A bus (contracted from omnibus, with variants multibus, motorbus, autobus, etc.) is a road vehicle that carries significantly more passengers than an average car or van. It is most commonly used in public transport, but is also in use for cha ...
architecture with no motherboard – all electronics were contained on a number of cards interconnected by
ribbon cable
A ribbon cable (also known as multi-wire planar cable) is a cable with many conducting wires running parallel to each other on the same flat plane. As a result, the cable is wide and flat. Its name comes from its resemblance to a piece of ribb ...
. The only
microprocessor
A microprocessor is a computer processor where the data processing logic and control is included on a single integrated circuit, or a small number of integrated circuits. The microprocessor contains the arithmetic, logic, and control circu ...
offered was a 4
MHz
The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that one he ...
Z80A
The Z80 is an 8-bit microprocessor introduced by Zilog as the startup company's first product. The Z80 was conceived by Federico Faggin in late 1974 and developed by him and his 11 employees starting in early 1975. The first working samples we ...
.
Memory
Memory was fitted in up to four banks of
RAM
Ram, ram, or RAM may refer to:
Animals
* A male sheep
* Ram cichlid, a freshwater tropical fish
People
* Ram (given name)
* Ram (surname)
* Ram (director) (Ramsubramaniam), an Indian Tamil film director
* RAM (musician) (born 1974), Dutch
* ...
, each of either 4
KB (4 × 1024
byte
The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable unit ...
s) or 16 KB, although not every permutation was permitted.
Typical configurations were 16 KB for cassette-based systems and 32, 48 or 64 KB of memory on disk-based systems. Main memory was not used by the text or graphics video cards, although memory on the video cards was
bank switched into a dedicated 1.5 KB address block.
The 380Z was also fitted with up to 6 KB of
firmware
In computing, firmware is a specific class of computer software that provides the low-level control for a device's specific hardware. Firmware, such as the BIOS of a personal computer, may contain basic functions of a device, and may provide h ...
, known as COS.
On systems fitted with less than 64 KB of RAM the COS reserved 1 KB of system RAM, leaving the rest available to the user. On the 64 KB RAM system a total of 56 KB was available to the user, with the remainder used by COS or inaccessible because of the firmware
ROM
Rom, or ROM may refer to:
Biomechanics and medicine
* Risk of mortality, a medical classification to estimate the likelihood of death for a patient
* Rupture of membranes, a term used during pregnancy to describe a rupture of the amniotic sac
* ...
, video card, and
memory-mapped I/O
Memory-mapped I/O (MMIO) and port-mapped I/O (PMIO) are two complementary methods of performing input/output (I/O) between the central processing unit (CPU) and peripheral devices in a computer. An alternative approach is using dedicated I/O pro ...
.
Video
COS 3.4 (see
below
Below may refer to:
*Earth
*Ground (disambiguation)
*Soil
*Floor
*Bottom (disambiguation)
Bottom may refer to:
Anatomy and sex
* Bottom (BDSM), the partner in a BDSM who takes the passive, receiving, or obedient role, to that of the top or ...
) and earlier systems came with a basic
video card
A graphics card (also called a video card, display card, graphics adapter, VGA card/VGA, video adapter, display adapter, or mistakenly GPU) is an expansion card which generates a feed of output images to a display device, such as a computer moni ...
providing a 40×24
text-only monochrome display.
Composite video
Composite video is an analog video signal format that carries standard-definition video (typically at 525 lines or 625 lines) as a single channel. Video information is encoded on one channel, unlike the higher-quality S-Video (two channels) a ...
output was provided for an external monitor, and an internal
RF modulator
An RF modulator (or radio frequency modulator) is an electronic device whose input is a baseband signal which is used to modulate a radio frequency source.
RF modulators are used to convert signals from devices such as media players, VCRs a ...
provided a separate output to drive a television set. Later systems were supplied with an enhanced video card that was software-switchable between 40×24 and 80×24 character modes and supported a number of character attributes (underline, dim, reverse-video).
Both card types were fitted with their own dedicated video memory.
In addition to the text-mode video card the system could be enhanced with a
high-resolution
Image resolution is the detail an image holds. The term applies to digital images, film images, and other types of images. "Higher resolution" means more image detail.
Image resolution can be measured in various ways. Resolution quantifies how cl ...
graphics (HRG) board. The board was fitted with a dedicated bank of 16 KB of video memory and supported two graphics modes:
*High resolution: 320×192
pixel
In digital imaging, a pixel (abbreviated px), pel, or picture element is the smallest addressable element in a raster image, or the smallest point in an all points addressable display device.
In most digital display devices, pixels are the smal ...
s, 2
bits per pixel
Color depth or colour depth (see spelling differences), also known as bit depth, is either the number of bits used to indicate the color of a single pixel, or the number of bits used for each color component of a single pixel. When referring to ...
(4 colours), 1
page
Page most commonly refers to:
* Page (paper), one side of a leaf of paper, as in a book
Page, PAGE, pages, or paging may also refer to:
Roles
* Page (assistance occupation), a professional occupation
* Page (servant), traditionally a young m ...
.
*Medium resolution: 160×96 pixels, 4 bits per pixel (16 colours), 2 pages.
A programmable
lookup table
In computer science, a lookup table (LUT) is an array that replaces runtime computation with a simpler array indexing operation. The process is termed as "direct addressing" and LUTs differ from hash tables in a way that, to retrieve a value v wi ...
with an
8-bit
In computer architecture, 8-bit Integer (computer science), integers or other Data (computing), data units are those that are 8 bits wide (1 octet (computing), octet). Also, 8-bit central processing unit (CPU) and arithmetic logic unit (ALU) arc ...
output mapped the pixel value to one of 256 different colours (analogue
RGB
The RGB color model is an additive color model in which the red, green and blue primary colors of light are added together in various ways to reproduce a broad array of colors. The name of the model comes from the initials of the three addi ...
output) or intensities (composite video).
In RGB mode, each palette index can configured by specifying the amount of each primary colour. Possible ranges are 0 to 7 for Red and Green, and 0 to 3 for Blue (ex: 000 generates black; 773 generates white). This arrangement is known as
8-bit color
8-bit color graphics are a method of storing image information in a computer's memory or in an image file, so that each pixel is represented by 8 bits (1 byte). The maximum number of colors that can be displayed at any one time is 256 or 28.
Color ...
and also used on other machines like the
MSX2
MSX is a standardized home computer architecture, announced by Microsoft and ASCII Corporation on June 16, 1983. It was initially conceived by Microsoft as a product for the Eastern sector, and jointly marketed by Kazuhiko Nishi, then vice-p ...
or
Atari Falcon
The Atari Falcon030 (usually shortened to Atari Falcon), released in 1992, was the final personal computer product from Atari Corporation. A high-end model of the Atari ST line, the machine is based on a Motorola 68030 CPU and a Motorola 56001 dig ...
.
Output from the graphics board was mixed with output from the text-only video card, allowing text and graphics to be easily overlaid. The graphics output only covered the top 20 lines of the text display and therefore text output could be set to use only the bottom 4 lines if overlap was not desired.
Storage
Mass storage
In computing, mass storage refers to the storage of large amounts of data in a persisting and machine-readable fashion. In general, the term is used as large in relation to contemporaneous hard disk drives, but it has been used large in relati ...
was either via
cassette tape
The Compact Cassette or Musicassette (MC), also commonly called the tape cassette, cassette tape, audio cassette, or simply tape or cassette, is an analog magnetic tape recording format for audio recording and playback. Invented by Lou Ottens ...
or
floppy disk
A floppy disk or floppy diskette (casually referred to as a floppy, or a diskette) is an obsolescent type of disk storage composed of a thin and flexible disk of a magnetic storage medium in a square or nearly square plastic enclosure lined w ...
(which required a
disk controller
{{unreferenced, date=May 2010
The disk controller is the controller circuit which enables the CPU to communicate with a hard disk, floppy disk or other kind of disk drive. It also provides an interface between the disk drive and the bus conne ...
card). The cassette interface operated at either 300 bit/s (
CUTS standard) or 1200 bit/s.
COS 4.0 and later systems were not fitted with the cassette interface.
Early systems could be fitted with an optional
single density
Disk density is a capacity designation on magnetic storage, usually floppy disks. Each designation describes a set of characteristics that can affect the areal density of a disk or the efficiency of the encoded data. Such characteristics include ...
floppy disk controller
A floppy-disk controller (FDC) has evolved from a discrete set of components on one or more circuit boards to a special-purpose integrated circuit (IC or "chip") or a component thereof. An FDC directs and controls reading from and writing to ...
card that could interfaced to either internal 5¼-inch or external 8-inch floppy disk drives. Disk capacity was 80 KB per side on 5¼-inch disks and 250.25 KB per side on 8-inch disks. Double-sided disk drives were treated as two independent disks with a
drive letter
In computer data storage, drive letter assignment is the process of assigning alphabetical identifiers to volumes. Unlike the concept of UNIX mount points, where volumes are named and located arbitrarily in a single hierarchical namespace, driv ...
per side.
CP/M used the first 4 tracks on 5¼-inch disks and the first 3 tracks on 8-inch disks, reducing the usable capacity of a single density, single-sided 5¼-inch disk to 72 KB.
Later systems (referred to as the 380Z-D) were fitted with a
double density
Disk density is a capacity designation on magnetic storage, usually floppy disks. Each designation describes a set of characteristics that can affect the areal density of a disk or the efficiency of the encoded data. Such characteristics include ...
Intelligent Disc Controller (IDC), which increased disk capacity to either 180 KB (48
TPI drives) or 360 KB (96 TPI drives) per side on 5¼-inch disks and 500.5 KB per side on 8-inch disks.
Support for a "Winchester"
hard disk drive
A hard disk drive (HDD), hard disk, hard drive, or fixed disk is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage with one or more rigid rapidly rotating platters coated with magnet ...
could be provided using an intelligent Host Interface Board (HIB) that implemented a
SASI interface. Hard disk systems were mainly used as
file server
In computing, a file server (or fileserver) is a computer attached to a network that provides a location for shared disk access, i.e. storage of computer files (such as text, image, sound, video) that can be accessed by the workstations that are ab ...
s for networked
LINK 480Z systems.
Interface cards
The passive bus allowed a number of cards to be installed in the 380Z. All systems required:
*CPU/RAM – holding the Z80A
CPU, firmware ROMs, and up to 32 KB of RAM. The card also provided a parallel
Centronics printer port
IEEE 1284 is a standard that defines bi-directional parallel communications between computers and other devices. It was originally developed in the 1970s by Centronics, and was widely known as the Centronics port, both before and after its IEEE ...
(not always connected).
*Video, either a VDU-40 or VDU-80 card – providing the 40×24 or the switchable 80×24/40×24 character text displays, respectively.
Other cards were optional, and included:
*RAM – a second CPU/RAM board, with processor and ROMs omitted, holding up to a further 32 KB of RAM.
*Floppy Disc Controller (FDC) – a single density disk controller, which also provided an
RS-232
In telecommunications, RS-232 or Recommended Standard 232 is a standard originally introduced in 1960 for serial communication transmission of data. It formally defines signals connecting between a ''DTE'' (''data terminal equipment'') such a ...
serial interface (SIO-4).
*Intelligent Disc Controller (IDC) – a double density disk controller with its own dedicated microprocessor.
*High Resolution Graphics (HRG) – up to 320×192 pixels.
*Host Interface Board (HIB) – for hard disk support.
*380Z Network Interface Board (380Z-NET) – a proprietary 800 kbit/s network interface used to interconnect to a network of LINK 480Zs.
*Serial Interface-1 (SIO-1) – available as the SIO-1A (RS-232) or SIO-1B (20 mA
current loop
In electrical signalling an analog current loop is used where a device must be monitored or controlled remotely over a pair of conductors. Only one current level can be present at any time.
A major application of current loops is the industry de ...
).
*Serial Interface-2 (SIO-2) – available as the SIO-2 (RS-232) or SIO-2B/SIO-3 (20 mA current loop).
*Serial Interface-4C (SIO-4C) – providing an SIO-4 interface on cassette systems without the FDC card.
*
IEEE-488
IEEE 488 is a short-range digital communications 8-bit parallel multi-master interface bus specification developed by Hewlett-Packard as HP-IB (Hewlett-Packard Interface Bus). It subsequently became the subject of several standards, and is ...
Interface.
*PIO Interface Development Board – providing three Z80 PIOs and a Z80 CTC.
*Analogue I/O Board – providing 16 input channels and 2 output channels.
Firmware
Boot monitor
The system firmware contained only a basic monitor program, known as COS (standing for Cassette Operating System in the COS 3.4 and earlier systems
and Central Operating System in the later disk-only systems
). The monitor could be used to load application programs, such as
BASIC
BASIC (Beginners' All-purpose Symbolic Instruction Code) is a family of general-purpose, high-level programming languages designed for ease of use. The original version was created by John G. Kemeny and Thomas E. Kurtz at Dartmouth College ...
, from cassette or to
boot
A boot is a type of footwear. Most boots mainly cover the foot and the ankle, while some also cover some part of the lower calf. Some boots extend up the leg, sometimes as far as the knee or even the hip. Most boots have a heel that is cle ...
the disk operating system. COS also provided a software
front panel
A front panel was used on early electronic computers to display and allow the alteration of the state of the machine's internal registers and memory. The front panel usually consisted of arrays of indicator lamps, digit and symbol displays, to ...
allowing the display of registers and memory, and supporting
breakpoint
In software development, a breakpoint is an intentional stopping or pausing place in a program, put in place for debugging purposes. It is also sometimes simply referred to as a pause.
More generally, a breakpoint is a means of acquiring knowle ...
s and single-stepping of machine code.
The COS monitor was stored in either 4 KB (COS 3.4 and earlier) or 6 KB (COS 4.0 and later) of ROM;
in the latter case part of the ROM was bank switched.
COS services
COS provided a number of basic hardware control functions, such as keyboard input, writing text to the video card and disk
input/output
In computing, input/output (I/O, or informally io or IO) is the communication between an information processing system, such as a computer, and the outside world, possibly a human or another information processing system. Inputs are the signals ...
. COS functions were called by means of the Emulator
Trap
A trap is a mechanical device used to capture or restrain an animal for purposes such as hunting, pest control, or ecological research.
Trap or TRAP may also refer to:
Art and entertainment Films and television
* ''Trap'' (2015 film), Fil ...
(EMT) pseudo-
opcode
In computing, an opcode (abbreviated from operation code, also known as instruction machine code, instruction code, instruction syllable, instruction parcel or opstring) is the portion of a machine language instruction that specifies the operat ...
, which used the Z80 RST 30H instruction to
call
Call or Calls may refer to:
Arts, entertainment, and media Games
* Call, a type of betting in poker
* Call, in the game of contract bridge, a bid, pass, double, or redouble in the bidding stage
Music and dance
* Call (band), from Lahore, Paki ...
the EMT handler function.
The EMT handler read the first byte following the RST 30H instruction to determine which EMT function was being requested; all parameters were passed in registers. A
call
Call or Calls may refer to:
Arts, entertainment, and media Games
* Call, a type of betting in poker
* Call, in the game of contract bridge, a bid, pass, double, or redouble in the bidding stage
Music and dance
* Call (band), from Lahore, Paki ...
-
relative
Relative may refer to:
General use
*Kinship and family, the principle binding the most basic social units society. If two people are connected by circumstances of birth, they are said to be ''relatives''
Philosophy
*Relativism, the concept that ...
pseudo-opcode was also implemented using RST 28H.
Main COS versions
COS versions were mainly tied to the new hardware functions they supported.
*COS 2.2 –
*COS 2.3 – cassette-only, 40×24 video card.
*COS 3.0 – floppy disk support.
*COS 3.4 – main COS version supporting single density disks and the 40×24 video card.
*COS 4.0 – 80×24 text display, no cassette support.
*COS 4.2 – double density disk drives (380Z-D).
Software
Operating systems
The main
disk operating system was
CP/M
CP/M, originally standing for Control Program/Monitor and later Control Program for Microcomputers, is a mass-market operating system created in 1974 for Intel 8080/ 85-based microcomputers by Gary Kildall of Digital Research, Inc. Initial ...
, initially CP/M 1.4 and later CP/M 2.2.
MP/M
MP/M (Multi-Programming Monitor Control Program) is a discontinued multi-user version of the CP/M operating system, created by Digital Research developer Tom Rolander in 1979. It allowed multiple users to connect to a single computer, each us ...
II was used on the file server version, which supported a network of LINK 480Z computers using CP/NET.
Application software
Many standard CP/M applications were available, such as
WordStar
WordStar is a word processor application for microcomputers. It was published by MicroPro International and originally written for the CP/M-80 operating system, and later written also for MS-DOS and other 16-bit PC OSes. Rob Barnaby was the sol ...
. Research Machines also produced their own
assembler
Assembler may refer to:
Arts and media
* Nobukazu Takemura, avant-garde electronic musician, stage name Assembler
* Assemblers, a fictional race in the ''Star Wars'' universe
* Assemblers, an alternative name of the superhero group Champions of A ...
(ZASM),
text editor
A text editor is a type of computer program that edits plain text. Such programs are sometimes known as "notepad" software (e.g. Windows Notepad). Text editors are provided with operating systems and software development packages, and can be us ...
(TXED) and BASIC
interpreter.
Brian Reffin Smith
Brian Reffin Smith (born 1946) is an artist, writer, teacher and musician born in Sudbury, Suffolk, in the United Kingdom, who won the first-ever Prix Ars Electronica, the Golden Nica, in Linz, Austria, 1987. He lives in Berlin, Germany.
Life
Br ...
, then at the
Royal College of Art
The Royal College of Art (RCA) is a public research university in London, United Kingdom, with campuses in South Kensington, Battersea and White City. It is the only entirely postgraduate art and design university in the United Kingdom. It offe ...
in London, wrote 'Jackson', one of the first digital painting programs, which ran on the 380Z and which was distributed across UK schools.
References
{{reflist, 30em
External links
RM 380Z on old-computers.comgroups.io Research Machines RML380Z and 480Z GroupVT100.net page with scanned-in manuals
Early microcomputers
Personal computers
Z80-based home computers