The TRS-80 Color Computer, IBM PCjr, MSX, and BBC Micro from Acorn Computers all contained a built-in relay for controlling an external tape recorder.

The machine was primarily aimed at the home and educational markets, and it copied the IBM PCjr's 16-color graphics ( PCjr's graphics were an extension of CGA video ) and 3-voice sound, but didn't use the PCjr cartridge ports.

As the Tandy 1000 line outlasted the PCjr by many years ( and in fact did not make it to market until shortly before IBM announced the discontinuation of the PCjr ) these graphics and sound standards became known as " Tandy-compatible " or ( for the graphics ) " TGA " ( standing for Tandy Graphics Adapter ) and many software packages of the era listed their support for Tandy standard hardware on the package.

The earlier 1000 / 1000A, 1000 HD, 1000 EX and 1000 HX models, like the IBM PCjr, did not have a DMA controller, but could be upgraded with one.

It introduced products such as the IBM PC Convertible which was outsold by the heavier but much earlier and more compatible Compaq Portable, and the PCjr, which had significant incompatibilities with the original PC and was soon discontinued.

Sierra On-Line was contacted by IBM in 1983 to create a game for its new PCjr.

VGA is not compatible with the special IBM PCjr or HGC video modes.

Another bus that offered stackable expansion modules was the " sidecar " bus used by the IBM PCjr.

Epyx also ported Jumpman to the Apple II, and a year later contracted Mirror Images Software for an IBM PC / PCjr port.

Predictably a minor upgrade, it fixed some bugs and added support for half height floppy drives and the new IBM PCjr.

Rhapsody in Blue has also been used in connection with various IBM products, including the PCjr.

IBM released their painting package, Color Paint, for the IBM PCjr for US $ 100.

The PCjr, IBM model number 4860, retained the IBM PC's 8088 CPU and BIOS interface for compatibility, but various design and implementation decisions led the PCjr to be a commercial failure.

The PCjr promised a high degree of compatibility with the IBM PC, which was already a popular business computer, in addition to offering built-in color graphics and 3 voice sound that were better than the standard PC speaker sound and color graphics of the standard IBM PC and compatibles of the day.

Other than the Tandy 1000 and Amstrad IBM PC compatible lines a few years later, the dual built-in joystick ports introduced by the PCjr never became standard on IBM PC compatibles, and have not been seen since.

IBM launched the PCjr at its New York City headquarters with an enormous amount of advance publicity, including live news-broadcast coverage of the product announcement.

Time called its debut " D-Day for the Home Computer "; observers predicted sales of one million or more in 1984, and expected the PCjr to change the home-computer market in a similar way to how the IBM PC had single-handedly changed the business-microcomputer market.

When the LOAD button on the IBM 1402 Card Read-Punch was pressed, a card was read into memory locations 001-080, a word mark was set in location 001, the word marks in locations 002-080 were cleared, and execution started with the instruction at location 001.

The IBM 550 numerical interpreter was the first commercial machine made by IBM that read numerical data punched on cards and printed it across the top of each card.

It became common to use a less expensive IBM 1401 computer to read cards onto magnetic tape for transfer to the 7090 / 94.

Since terminals were connected through various types of front-end processors ( as per common IBM timesharing practice both then and now ), and could therefore function without CPU attention for a considerable amount of time, MUSIC used variable-length time slices, which could, on compute-bound processing, reach a maximum of several seconds per time slice ; conversely, if a user filled the output buffer or reached a conversational read, the timeslice would end immediately.

The firmware of the disk controllers was compatible with that for IBM PC, and programs were available to read FAT formatted disks.

Other word processors, such as OpenOffice. org Writer, IBM Lotus Symphony, Google Docs, Apple Pages and AbiWord, can also create and read DOC files, although with some limitations.

This was made possible as the SuperDrive now utilitized the same MFM ( Modified Frequency Modulation ) encoding scheme used by the IBM PC, yet still retained backward compatibility with Apple's variable-speed zoned CAV scheme and Group Code Recording encoding format, so it could continue to read Macintosh MFS, HFS and Apple II ProDOS formats on 400 / 800K disks.

The first mark sense scanner was the IBM 805 Test Scoring Machine ; this read marks by sensing the electrical conductivity of graphite pencil lead using pairs of wire brushes that scanned the page.

It read and punched 80-column IBM-format punched cards and was used on the IBM 1440, the IBM 1130, the IBM 1800 and System / 360 and was an option on the IBM System / 3.

Cards were read using photocells, illuminated by fiber optics, unlike the IBM 1402, which still used wire brushes to read cards.

It was even possible to create ( but not read ) " IBM Doilies ," cards with every possible hole punched.

In Volume 16, Number 1, Page 41 ( 1977 ) of the IBM Systems Journal the article " The IBM 5100 and the Research Device Coupler — A personal laboratory automation system " read: " A small laboratory automation system has been developed by using the IBM 5100 Portable Computer in conjunction with the Research Device Coupler.

It had 16 kB or 32 kB of memory, a single hard drive that was available in 5 MB, 9 MB, or 13 MB sizes, and an eight-inch floppy drive, this drive could also read floppies from the IBM 3740 family.

Unlike earlier IBM tabulating machines, which had one read brush per column at each read station, the 407 had 960 brushes at each station, one for each possible hole in a punched card.

IBM first introduced the 8-inch FDD in 1971 as a read only program load device.

In 1973 IBM shipped its first read / write floppy disk drive as a part of the 3740 Data Entry System.

However, poor marketing and failure to repeat the technological advances of the first systems meant that the Amiga quickly lost its market share to competing platforms, such as the fourth generation game consoles, Apple Macintosh and IBM PC compatibles.

It was also a less expensive alternative to the Apple Macintosh and IBM PC as a general-purpose business or home computer.

The original AIX ( sometimes called AIX / RT ) was developed for the IBM 6150 RT workstation by IBM in conjunction with Interactive Systems Corporation, who had previously ported UNIX System III to the IBM PC for IBM as PC / IX.

Versions were also released for the IBM PC and compatibles, and the Apple IIGS.

These included updates to EtherTalk and TokenTalk, AppleTalk software and LocalTalk hardware for the IBM PC, EtherTalk for Apple's A / UX operating system allowing it to use LaserPrinters and other network resources, and the Mac X. 25 and MacX products.

The first model looked like the later IBM PC ( which came on the market years later ), a rectangular base unit with two floppy drives on the front, and a monitor on top with a separate detachable keyboard.

In the meantime IBM had released its original IBM PC, which incidentally looked remarkably like the Asters base with floppy drives + separate keyboard set-up.

A few years later, in 1981, IBM introduced the first DOS based IBM PC, and due to the overwhelming popularity of PCs and their clones, DOS soon became the operating system on which the majority of BBS programs were run.

This drive was one of several types installed into the IBM PC / XT and extensively advertised and reported as a " 10 MB " ( formatted ) hard disk drive.

For example, the internal clock frequency of the original IBM PC was 4. 77 MHz, that is, Hz.

Early personal computers like the Apple II and the IBM PC integrated an internal backplane for expansion cards.

Backplanes have grown in complexity from the simple Industry Standard Architecture ( ISA ) ( used in the original IBM PC ) or S-100 style where all the connectors were connected to a common bus.

In IBM PC compatible computers, the Basic Input / Output System ( BIOS ), also known as the system BIOS or ROM BIOS (), is a de facto standard defining a firmware interface.

In the IBM PC and AT, certain peripheral cards, such as hard-drive controllers and video display adapters, carried their own BIOS extension Option ROM, which provided additional functionality.

For example, an IBM PC might have either a monochrome or a color display adapter ( using different display memory addresses and hardware ), but a single, standard, BIOS system call may be invoked to display a character at a specified position on the screen in text mode.

So by reducing the number of tracks used and thus capacity, it was possible to further reduce cost-in contrast to Double Density drives used e. g. in IBM PC computers of the day which saved 180 kB on one side ( by using a 40 tracks format ).