Memotech MTX512 (Thomas Conté)
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The Memotech MTX500 and MTX512 are a range of
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Zilog
Z80A The Zilog Z80 is an 8-bit microprocessor designed by Zilog that played an important role in the evolution of early personal computing. Launched in 1976, it was designed to be software-compatible with the Intel 8080, offering a compelling altern ...
based home computers released by the British company
Memotech Memotech MTX512 computer Memotech Limited was a British computer company founded by Geoff Boyd and Robert Branton in Witney in Oxfordshire, England. They started out during the early 1980s producing memory expansion packs ("RAMpacks") and other ...
in 1983 and sold mainly in the UK, France, Germany and
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. Originally a manufacturer of memory add-ons for
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machines, Memotech developed their own competing computer when it was perceived the expansion pack business would no longer be viable. The Memotech machines were technically similar to, although not compatible with, the
MSX MSX is a standardized home computer architecture, announced by 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, the director at ASCII Corpo ...
standard, making use of the same
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and video chip. The machines were particularly distinguished from other
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 (P ...
s available at the time by the generous maximum memory ceiling. The 500 and 512 models could be expanded internally up to 512K, an unusually large amount of
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in 1983 for a computer aimed at home use. The MTX range saw the addition of the RS128 in 1984 which was a similar machine but with more memory. The machines achieved only modest sales, not assisted by the unfortunate timing of being released shortly before a period of reducing interest in UK home micro purchases through 1984, when a number of other British micro manufacturers entered financial difficulties. The MTX was selling into a highly competitive space, with the much cheaper
Sinclair ZX Spectrum The ZX Spectrum () is an 8-bit home computer developed and marketed by Sinclair Research. One of the most influential computers ever made and one of the all-time bestselling British computers, over five million units were sold. It was release ...
finding favour with home users, the
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conquering the education market and the
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making inroads into becoming a standard for business. The prospect of a very large contract with the
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was on the horizon by 1985 and a Russian version of the machine was designed, complete with a bright red case. This could have been the saviour of the range but ultimately the deal fell through and Memotech entered bankruptcy. The company was subsequently relaunched and the final version of the machine was the MTX512 Series 2 released in 1986, produced mainly as a way of using up stocks of parts before the business moved on to other ventures. The MTX512 (together with the FDX floppy drive peripheral) is remembered for an appearance in the 1985 comedy movie ''
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'' where it had a central role in the plot, being used to conjure the character Lisa played by
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.


Technical specifications

The MTX500 was fitted as standard with 32 KB of user
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, while the MTX512 had 64KB, and the RS128 had 128KB. An additional 16KB of dedicated
video RAM Video random-access memory (VRAM) is dedicated computer memory used to store the pixels and other graphics data as a framebuffer to be rendered on a computer monitor. It often uses a different technology than other computer memory, in order to b ...
was also present. By contrast, many other machines of the era used a non-trivial fraction of the advertised total memory for video display and the RAM available to the user was less than it may have seemed. All machines had a
Zilog Z80A The Zilog Z80 is an 8-bit microprocessor designed by Zilog that played an important role in the evolution of early personal computing. Launched in 1976, it was designed to be software-compatible with the Intel 8080, offering a compelling altern ...
CPU running at 4 MHz which could only address a maximum of 64KB at any one time, larger amounts of RAM were accessed through
bank switching Bank switching is a technique used in computer design to increase the amount of usable memory beyond the amount directly addressable by the Processor (computing), processor instructions. It can be used to configure a system differently at diffe ...
. The machine featured a
TMS9918 IMAGE:TMS9918A 01.jpg, VDP TMS9918A IMAGE:TMS9918A 02.jpg, VDP TMS9918A The TMS9918 is a video display controller (VDC) manufactured by Texas Instruments, in manuals referenced as "Video Display Processor" (VDP) and introduced in 1979. The TMS9918 ...
series video chip, either a TMS9929A or TMS9928A depending on the region, providing a resolution of 256 x 192 in 15 colours (plus transparent) and up to 32 sprites. A SN76489A sound chip generated 3 voices plus a
pink noise Pink noise, noise, fractional noise or fractal noise is a signal (information theory), signal or process with a frequency spectrum such that the power spectral density (power per frequency interval) is inversely proportional to the frequenc ...
channel with a 6
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range. The system interfaces offered were a Centronics printer port, two joystick ports, a proprietary Z80 bus
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(which doubled as a cartridge port), 2400
baud In telecommunications and electronics, baud (; symbol: Bd) is a common unit of measurement of symbol rate, which is one of the components that determine the speed of communication over a data channel. It is the unit for symbol rate or modulat ...
cassette ports (mic and ear), RF for use with a TV,
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outputs and an audio jack. An "uncommitted" generic I/O port was available but there was no external connector; this was supplied from a DIL socket on the motherboard. There was one internal expansion slot that could accept two expansion cards via daisy chaining. An optional "communications" board was available for use with the internal slot, which added two 19,200 baud
RS-232 In telecommunications, RS-232 or Recommended Standard 232 is a standard introduced in 1960 for serial communication transmission of data. It formally defines signals connecting between a ''DTE'' (''data terminal equipment'') such as a compu ...
interfaces and an interface for the FDX disk peripheral. Networking was supported over RS-232 via the communications board and up to 255 MTX machines could be connected with the MTX "Node/Ring" system. All models had 24KB of
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 * ...
accessible in the first 16KB of
address space In computing, an address space defines a range of discrete addresses, each of which may correspond to a network host, peripheral device, disk sector, a memory cell or other logical or physical entity. For software programs to save and retrieve ...
. The extra 8KB of ROM was available through bank switching. The ROM could be switched out entirely, allowing the full 16-bit address space to be used for RAM. The Memotech series featured an aluminium case and full-size 79-key keyboard with mechanical full-travel keys. This was a distinctive feature as many competing home computers of the time used a cost-reduced chiclet,
membrane A membrane is a selective barrier; it allows some things to pass through but stops others. Such things may be molecules, ions, or other small particles. Membranes can be generally classified into synthetic membranes and biological membranes. Bi ...
or rubber keyboard that was difficult to type on.


Software

An MTX variant of the BASIC language interpreter was supplied on ROM as standard, which was a user expectation in the mid 80s for a home computer. The BASIC had extended graphics commands and also integrated support for
turtle graphics In computer graphics, turtle graphics are vector graphics using a relative cursor (the "turtle") upon a Cartesian plane (x and y axis). Turtle graphics is a key feature of the Logo programming language. It is also a simple and didactic way of d ...
in the style of the
Logo A logo (abbreviation of logotype; ) is a graphic mark, emblem, or symbol used to aid and promote public identification and recognition. It may be of an abstract or figurative design or include the text of the name that it represents, as in ...
language used in education. A Z80 assembler/disassembler was also included. The
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and
object Object may refer to: General meanings * Object (philosophy), a thing, being, or concept ** Object (abstract), an object which does not exist at any particular time or place ** Physical object, an identifiable collection of matter * Goal, an a ...
versions of
machine code In computer programming, machine code is computer code consisting of machine language instructions, which are used to control a computer's central processing unit (CPU). For conventional binary computers, machine code is the binaryOn nonb ...
programs occupied the same space in RAM allowing for storage within less memory. Machine code could also be mixed arbitrarily with BASIC to enhance software performance. This was a rarer feature, but was seen in the BASIC of some other contemporary machines such as the
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and Camputers Lynx. A
machine code monitor A machine code monitor ( machine language monitor) is software that allows a user to enter commands to view and change memory address, memory locations on a computer, with options to load and save memory contents from/to secondary storage. Some f ...
was included called Front Panel that could be used for debugging programs. Monitors were popular in the 1970s as a method of interacting with computers but were a less common standard feature when the Memotech was released. A novel proprietary
programming language A programming language is a system of notation for writing computer programs. Programming languages are described in terms of their Syntax (programming languages), syntax (form) and semantics (computer science), semantics (meaning), usually def ...
called MTX Noddy was available in ROM that was a card based information retrieval system somewhat similar in concept to
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. A set of cards can be filled with arbitrary information using an integrated text editor (the user can type anywhere on the screen) and then saved for later retrieval by name. A simplified Noddy programming language aimed at novices allows the cards to be linked together with logic steps based on if/else statements. The user can be asked questions and based on the typed response, the Noddy program then advances to another card. From this software such as simple databases, an
expert system In artificial intelligence (AI), an expert system is a computer system emulating the decision-making ability of a human expert. Expert systems are designed to solve complex problems by reasoning through bodies of knowledge, represented mainly as ...
or text adventure games could be constructed. Noddy cards could also be integrated with BASIC. The name of the software is a reference to British slang, meaning simple or trivial. The Memotech supported "virtual screens" which were a form of primitive
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. Areas of the screen could be defined that operated independently and the user could switch between them for different tasks. The output of a program could be directed to one user defined window and then the output of a different program to another window. The Memotech did not use a mouse, window size and position on the screen was controlled using commands. While the concept had been previously invented, windowing support was an uncommon feature for a personal computer in 1983. The
Macintosh Mac is a brand of personal computers designed and marketed by Apple Inc., Apple since 1984. The name is short for Macintosh (its official name until 1999), a reference to the McIntosh (apple), McIntosh apple. The current product lineup inclu ...
and subsequent
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that popularised the windowing user interface style would not be released until later years. The MTX could run the
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and a license for CP/M 2.2 was included with the purchase of the optional FDX and HDX disk peripherals. Use of CP/M enabled compatibility with a large library of existing software applications and enabled the machine to be a viable business proposition. At this time, the soon to be dominant
MS-DOS MS-DOS ( ; acronym for Microsoft Disk Operating System, also known as Microsoft DOS) is an operating system for x86-based personal computers mostly developed by Microsoft. Collectively, MS-DOS, its rebranding as IBM PC DOS, and a few op ...
was only at the beginning of its ascent and CP/M was a widely popular platform for software releases.


Peripherals

The FDX (Floppy Disk Expansion) was a data storage peripheral with space for expansion cards. The device could be used with any of the machines in the range but at least 64 KB of RAM was needed, necessitating an upgrade for the Memotech 500 model, and required the optional communications board to which it attached with a
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. It was sold with either one or two 5.25"
floppy disk A floppy disk or floppy diskette (casually referred to as a floppy, a diskette, or a disk) is a 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 with a ...
drives installed and contained a SASI interface supporting up to four drives in total. The system also supported older 8" floppy drives. Four
RAM disk A RAM drive (also called a RAM disk) is a block of random-access memory ( primary storage or volatile memory) that a computer's software is treating as if the memory were a disk drive (secondary storage). RAM drives provide high-performance te ...
cards (referred to as silicon disks) could be added within the FDX chassis, each with up to 8 MB of storage, providing 32 MB of
solid state storage A solid-state drive (SSD) is a type of solid-state storage device that uses integrated circuits to store data persistently. It is sometimes called semiconductor storage device, solid-state device, or solid-state disk. SSDs rely on non-v ...
in total. These cards could emulate drives accessible by CP/M with the intent of accelerating software performance versus running software from mechanical disks. In contrast to modern
SSD A solid-state drive (SSD) is a type of solid-state storage device that uses Integrated circuit, integrated circuits to store data persistence (computer science), persistently. It is sometimes called semiconductor storage device, solid-stat ...
s, these disks were volatile, meaning the data was lost when power is removed. An optional colour 80 column x 24 row video card could also be added to the FDX unit, a display mode which was often perceived as important for running popular business software such as
WordStar WordStar is a discontinued word processor application for microcomputers. It was published by MicroPro International and originally written for the CP/M-80 operating system (OS), with later editions added for MS-DOS and other 16-bit computing, ...
and
SuperCalc SuperCalc is a spreadsheet published by Sorcim in 1980. History VisiCalc was the first spreadsheet program, but at first was not available for the CP/M operating system. SuperCalc was created to serve that market. Alongside WordStar, it wa ...
, but was not natively supported by the MTX system. A novel feature was multiple monitor support, which was rare for a 1980s personal computer. The MTX internal video could be output simultaneously with the FDX video output. This enabled e.g. a program listing to be displayed on one monitor with the output of the program on another. The card also offered
teletext Teletext, or broadcast teletext, is a standard for displaying text and rudimentary graphics on suitably equipped television sets. Teletext sends data in the broadcast signal, hidden in the invisible vertical blanking interval area at the to ...
character compatibility, a 160 x 96 graphics mode and supported a
light pen A light pen is a computer input device in the form of a light-sensitive wand used in conjunction with a computer's cathode-ray tube (CRT) display. It allows the user to point to displayed objects or draw on the screen in a similar way to a to ...
. With the addition of the FDX peripheral, the MTX resembled a desktop PC configuration but the system logic was mostly contained within the keyboard and the FDX unit was principally a storage add-on. A variant of the FDX called the HDX was produced, that was sold with a 5 - 20 MB hard disk combined with a single 5.25" floppy drive. A small SDX disk controller peripheral was also manufactured that allowed connection of external floppy drive units. A version was also available that had a 3.5" drive integrated. These units did not require the communications board and plugged into the left side edge connector. A Memotech monitor was made available around the time of the FDX launch together with a branded
cassette deck A cassette deck is a type of tape machine for playing and recording audio cassettes that does not have a built-in power amplifier or speakers, and serves primarily as a Transport (recording), transport. It can be a part of an automotive entertai ...
and a Memotech printer with the part number DMX80, which was a rebadged
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model. A high resolution graphics adapter was available in 1984 called the HRX that could display close to true colour (218, or 262,144 colours) images at 256x256 pixel resolution and enabled frame capture from a video camera. This video mode was well beyond that typically offered on personal computers of the era. The attached MTX computer delivered image manipulation features such as scale, rotate, blur, sharpen,
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and contrast adjustment. It could also overlay painted
vector graphics Vector graphics are a form of computer graphics in which visual images are created directly from geometric shapes defined on a Cartesian plane, such as points, lines, curves and polygons. The associated mechanisms may include vector displ ...
onto the image. The HRX adapter was supplied as a separate chassis containing the video interface ADC/ DAC circuitry, additional RAM and a controller. An HRX system was priced at £4,500 (in 1984) and would form the basis of Memotech's later
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business.


References


External links


MTX information and reviews
- some text , content mostly
MTX family at old-computers.com

Review of MTX512
originally from ''
Creative Computing ''Creative Computing'' was one of the earliest magazines covering the microcomputer revolution. Published from October 1974 until December 1985, the magazine covered the spectrum of hobbyist/home/personal computing in a more accessible format t ...
''
Memotech MTX 512 - The Russian Schools Bid
{{Authority control Early microcomputers Z80-based home computers Home computers Computers designed in the United Kingdom Computer-related introductions in 1983