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70-536: The Tandy 1000 series began in 1984 as a clone of the IBM PCjr , offering support for existing PCjr software. As a result, its graphics subsystem is largely compatible. The PCjr, released in 1983, has a graphics subsystem built around IBM's Video Gate Array (not to be confused with the later Video Graphics Array ) and an MC6845 CRTC and extends on the capabilities of the Color Graphics Adapter (CGA), increasing

140-600: A shift register . It is similar to the programmable sound generator chips used in game consoles such as the Master System . The PCjr design also allows for an analog sound source in an expansion-bus "sidecar" module, and a software-controlled internal analog switch can select the source for the sound output from among the PC speaker , the SN76489, the cassette port, or the expansion-bus sound source. Only one sound source can be selected at

210-612: A TV or composite monitor. A Motorola 6845 CRTC like the one used in the MDA and CGA adapters, and a custom IBM chip called the Video Gate Array (VGA) constitute the bulk of the PCjr video hardware. Several discrete standard logic devices complete the video subsystem. The 6845 is responsible for the basic raster timing and video data address sequencing, and the Video Gate Array contains all

280-732: A Tandy 1000. IBM PCjr The IBM PCjr (pronounced "PC junior") was a home computer produced and marketed by IBM from March 1984 to May 1985, intended as a lower-cost variant of the IBM PC with hardware capabilities better suited for video games, in order to compete more directly with other home computers such as the Apple II and Commodore 64 . It retained the IBM PC's 8088 CPU and BIOS interface, but provided enhanced graphics and sound, ROM cartridge slots, built-in joystick ports, and an infrared wireless keyboard. The PCjr supported expansion via "sidecar" modules, which could be attached to

350-547: A backplane with eight card slots. It connects to the main system unit using an Extender Card in the system unit and a Receiver Card in the Expansion Unit, connected by a custom cable. The 5161 shipped with a 10 MB hard drive, and had room for a second one. The Expansion Unit can also contain extra memory, but the Extender card inserts wait states for memory in the Expansion Unit, so it may be preferable to install memory into

420-453: A built-in hard drive and extra expansion slots, it is very similar to the original IBM PC model 5150 from 1981. IBM did not specify an expanded form of "XT" on the machine, press releases, brochures or documentation, but some publications expanded the term as " eXtended Technology " or just " eXTended ". The XT was regarded as an incremental improvement over the PC and a disappointment compared to

490-407: A light pen (a rarely purchased option), this port can be used in combination with the serial port to supply voltage to a Mouse Systems optical mouse of the same design as those for Sun workstations . The back of the machine does not have any expansion slots. Instead, several permanently mounted, proprietary connectors provide attachment to many built-in hardware capabilities, which replaced many of

560-462: A pixel. Since the PCjr uses the main system RAM for the video buffer, less memory is available for software than on a standard PC, which has separate dedicated video memory in the A000h-BFFFh segments, above conventional memory. The PCjr's sound is provided by a Texas Instruments SN76496 which can produce three square waves of varying amplitude and frequency along with a noise channel powered by

630-536: A policy of strictly enforced security. The PCjr's graphics and sound features were superior to the PC's, and PC Magazine speculated that "the PCjr might be the best game machine ever designed". Prominent among launch titles was Sierra's graphical adventure King's Quest I , much of whose $ 850,000 budget was paid by IBM. The PCjr was released in March 1984, missing the 1983 Christmas sales season due to production delays. Even prior to release, anticipation of

700-412: A straightforward way. Cartridges can also replace the system BIOS and other firmware. A number of patches from various vendors are included on a single "combo-cartridge", licensed and sold by PC Enterprises, to support add-on hardware, bypass certain limitations of design, and keep up with changing OS requirements. Like the IBM PC, the PCjr uses an Intel 8088 clocked at 4.77 MHz. Despite using

770-415: A time; the sources cannot be mixed. The original keyboard included with the PCjr was a wireless design using infrared line-of-sight communication, which IBM initially marketed as the "Freeboard." This is a chiclet keyboard with small, flat, calculator style plastic keycaps. The keycaps are blank, with the labels printed between keys so that overlays can be used. The PCjr keyboard has 62 keys rather than

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840-448: A video mode switch. Of the three new modes, 160 x 200 x 16 mode has the same layout as CGA graphics modes; the odd and even scanlines are stored in the first and second half of the video buffer, each half being 8k in size, and every four bits represents one pixel. The 320 x 200 x 16 and 640 x 200 x 4 modes have four blocks of scanlines; every four or two bits respectively represents

910-549: Is approximately 19.5 inches (50 cm) wide by 16 inches (41 cm) deep by 5.5 inches (14 cm) high. Similarly to the original IBM PC, the XT main board included a socket for the Intel 8087 floating point arithmetic coprocessor . This optional chip, when installed, greatly accelerated arithmetic for such applications as computer aided design or other software that required large amounts of arithmetical calculations. Only software that

980-457: Is enough memory, a feature missing from the CGA. The CGA also did not provide a VBLANK interrupt, making it hard to detect when the screen was beginning to be drawn, but the PCjr provides this on IRQ 5, an important feature for smooth page-flipping. The video system also has a "blink" feature which toggles the palette between the first and second groups of eight palette registers at the same rate used for

1050-464: Is responsible for translating the 4-bit digital levels into 16 colors, as shown it the following table (actual colors could vary somewhat between monitors): The later Tandy 1000 SL and TL models offered an enhanced version of the TGA, still limited to displaying 16 colors but at an improved resolution of 640 × 200 . When operating in the CGA video modes which use 1 or 2 bits per pixel, TGA allows remapping of

1120-460: The Apple IIe . IBM repeatedly denied these rumors, but customers visited stores attempting to buy the product and rivals' revenue, product plans, and share prices reacted to the officially nonexistent computer in what the press called "Peanut Panic" or "The Great Peanut Roast". By September 1983, books and magazine articles on Peanut were ready for publishing, with only a few changes needed once

1190-615: The IBM PC XT upon which the PCjr is based, DRAM refresh is performed by one channel of the 8237 DMA controller, triggered by one channel of the 8253 programmable timer, while in the PCjr the 8237 is eliminated and the timer channel is repurposed (to work around a complication of other cost-cutting in the keyboard interface). Up to almost 128 KB of RAM can be used for video (if software is mostly in ROM—;e.g. on PCjr cartridges—or in RAM above

1260-623: The XT/370 ; they had an additional (co-)processor board that could execute System/370 instructions. An XT-based machine with a Series/1 co-processor board existed as well, but it had its own System Unit number, the IBM 4950 . In 1986, the XT 286 (model 5162) was released with a 6 MHz Intel 80286 processor. Despite being marketed as a lower-tier model than the IBM AT , this system runs many applications faster than

1330-651: The "Video System Logic"), common parlance referred to it as TGA. Where not otherwise stated, information in this article that describes the TGA also applies to the PCjr video subsystem. While EGA would eventually deliver a superset of TGA graphics on IBM compatibles, software written for TGA is not compatible with EGA cards. Tandy 1000 systems before the Tandy 1000 SL, and the PCjr, have this type of video. It offers several CGA-compatible modes and enhanced modes. CGA compatible modes: Both text modes could themselves be set to display in monochrome, or in 16 colors. In addition to

1400-503: The 2 or 4 palette entries to any of the 16 colors in the CGA gamut via programmable palette control registers. This allows software to use the CGA modes without being constrained to the three hardwired palettes of the actual CGA. The following improvements in color choice are available in the CGA graphics modes: The palette mapping logic is always active, even in text modes, so it is possible to cause certain text to change in appearance (appear, disappear, cycle colors, etc.) just by changing

1470-399: The 83 of the PC keyboard, and the remaining keys must be entered by holding a modifier key. For infrared wireless operation, the keyboard is powered by four AA cells. Certain types of room lighting can cause interference with the infrared keyboard sensor, and multiple keyboards cannot be used wirelessly in the same room without problems. IBM sold a cable which could be plugged in between

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1540-447: The ATs of the time with 6 MHz 286 processors, since it has zero- wait state RAM. It shipped with 640 KB RAM standard, an AT-style 1.2 MB high-density diskette drive and a 20 MB hard disk. Despite these features, reviews rated it as a poor market value. The XT 286 uses a 157-watt power supply, which can internally switch between 115 or 230 V AC operation. Both

1610-499: The BIOS routines for handling floppy access were different and more complex than those on the PC. Software that tried to perform direct, low-level disk access (mainly utilities, but also the occasional game such as Dunzhin: Warrior of Ras ) would not work unless it was rewritten for the PCjr. IBM's first home computer was the PC, released in 1981. Within two years the PC had created a large new ecosystem of hardware and software, nearly leading

1680-438: The CGA modes, it offers: Some games detect the Tandy hardware and display enhanced graphics in Tandy mode even when their CGA display mode is selected, while others offer the option to select "Tandy" graphics. Tandy 1000 SL-series, TL-series, and RL-series models have this type of video. It offers the same modes as Tandy Video I, plus one more non-CGA mode: With built-in joystick ports, 16-color graphics and multichannel sound,

1750-514: The Color Select Register (at I/O addresses 3D8h and 3D9h respectively), are not compatible, as the PCjr provides the equivalent functionality through different registers inside the Video Gate Array which are accessed in a completely different manner through a single I/O address (3DAh). The 6845 CRTC and the VGA together are responsible for refreshing the internal DRAM of the PCjr, which complicates

1820-497: The IBM Model M, but in a modified variant that used the XT's keyboard protocol and lacked LEDs). Submodels 267, 277 and 088 had the original keyboard, but 3.5" floppy drives became available and 20MB Seagate ST-225 hard disks in 5.25" half-height size replaced the full-height 10 MB drives. Submodel 788 was the only XT sold with the Color Graphics Adapter as a standard feature. Submodels 568, 588, and 589 were used as basis for

1890-490: The PC Portable, but the PCjr units were specially equipped with a small fan to prevent overheating since the computer did not have a case fan. The front of the PCjr exposes a pair of cartridge slots in which the user can insert software on ROM cartridges, as was common with other home computers. Each cartridge can contain up to 64 KB of ROM. When a ROM cartridge is inserted, the machine can automatically restart and boot off of

1960-451: The PCjr video subsystem continuously refreshes the system internal DRAM transparently, without disturbing the CPU, programs running from ROM on the PCjr may actually run slightly faster on the PCjr than on an IBM PC or XT. Unlike the IBM PC, which required a separate video card, the PCjr display hardware was built in to the system board. At the time, the only cards available from IBM for the PC were

2030-506: The PCjr was PC DOS, like the IBM PC, and it supported a large amount of PC software, with some incompatibilities. PC DOS 2.10 is the minimum version of DOS required for the PCjr. IBM's OEM versions of MS-DOS supported the machine up to DOS 3.30, but memory expansion was required for DOS 3.20 and 3.30. Like the original PC, the PCjr has BASIC in ROM, but includes Cartridge BASIC instead of Cassette BASIC. In addition to cartridge support, it extended

2100-468: The PCjr was not growing as rapidly as expected. By May 1984 it had only sold 10,000 units, while other companies were reported to be slow in developing software for the system. IBM Personal Computer XT The IBM Personal Computer XT (model 5160, often shortened to PC/XT ) is the second computer in the IBM Personal Computer line, released on March 8, 1983. Except for the addition of

2170-529: The PCs blinking text attribute, and a palette bit-masking feature that can be used to switch between palette subsets without reprogramming palette registers. Unlike CGA, PCjr has palette registers which allow the colors in all modes to be chosen from the full 16-color RGBI palette. When the BIOS is used to set a video mode, it sets up the palette table to emulate the CGA color palette for that mode. Programs specifically written to use PCjr graphics can subsequently reprogram

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2240-445: The ROM, without requiring the user to manually reboot. This auto-restart function is an optional feature of each cartridge: a cartidge can either restart the machine or not when it is inserted, depending on the construction of the cartridge. PCjr catridges are strictly read-only, unlike the software cartridges of some other contemporary computers and game consoles which can also be equipped with read/write memory (RAM) or I/O hardware in

2310-648: The Tandy 1000 was considered the best platform for IBM PC-compatible games before the VGA era, and the combination of its graphics and sound became a de facto standard, " Tandy compatible ". 28 of 66 games that Computer Gaming World tested in 1989 supported Tandy graphics. Titles such as Cisco Heat , Indiana Jones and the Last Crusade , Loom , Magic Pockets , Oh No! More Lemmings , Out of This World , Overkill , Prince of Persia , The Secret of Monkey Island and SimCity are indicated as supporting PCjr/Tandy graphics. A display driver for Tandy graphics hardware

2380-553: The XT. The 3270 PC , a variant of the XT featuring 3270 terminal emulation, was released in October 1983. Submodel 068 and 078, released in 1985, offered dual-floppy configurations without a hard drive as well, and the new Enhanced Graphics Adapter and Professional Graphics Adapter became available as video card options. In 1986, the 256–640 KB motherboard models were launched, which switched to half-height drives. Submodels 268, 278 and 089 came with 101-key keyboards (essentially

2450-517: The additional timing logic, video data demultiplexing logic, color processing logic, and programmable palette table logic, as well as the logic for multiplexing RAM access between the 8088 CPU and the video generation circuitry. For programming, the CRTC is generally compatible with the CGA at the hardware register level. Some other CGA programming details, in particular the Mode Control Register and

2520-451: The base 128 KB of RAM is divided into eight 16 KB banks. The PCjr can use any bank for video generation, in a video mode that uses 16 KB. In a mode that uses 32 KB, it can use any even bank concatenated with the next higher odd bank. The PCjr can also independently map any 16 KB bank of base RAM to address 0xB8000 for CPU access, for CGA compatibility. Apart from address 0xB8000, the CPU can access any bank at any time via its native address in

2590-416: The computer, stating that it would cost $ 600 plus $ 400 for a disk drive, use a color TV as a display, and have a standard typewriter keyboard. IBM announced the PCjr on November 1, 1983, at its New York City headquarters with an enormous amount of advance publicity, including live news coverage of the event. Experts predicted, according to The Washington Post , that the PCjr would "quickly become

2660-424: The features that PC expansion cards provided, including: Internally the PCjr did have expansion slots to support specific upgrades: a RAM upgrade, a modem, and a floppy drive. On the right side of the machine, the system bus was exposed for use with "sidecars," upgrade modules which attached to the side of the machine. Third-party manufacturers produced a number of expansion units for the PCjr. The primary OS for

2730-417: The first 128 KB of the address space. The first bank overlaps the interrupt vector table of the x86 CPU and the data area used by the BIOS, so it is generally not usable for graphics. Using system memory has advantages: It saves the cost of dedicated video RAM, and the dynamic RAM is refreshed by the 6845 CRT controller as long as the video is running, so there is no need for separate DRAM refresh circuitry. In

2800-414: The first 128 KB), and the displayed video banks can be switched instantaneously to implement double-buffering (or triple-buffering, or up to 7-fold buffering in 16 KB video modes) for smooth full-screen animation, something the CGA cannot do. The Tandy 1000 computers do not incorporate the PCjr's cost-cutting measures (most of them have an 8237 DMA controller), but for compatibility with PCjr video, they use

2870-451: The first 64 KB or 128 KB of RAM inside the system unit itself, and not to programs or data located in ROM - including software on ROM cartridges plugged into the front of the PCjr - or in additional RAM in a sidecar attachment. Under these circumstances the PCjr should run at full speed. The most common instances in which this maximum speed would be achieved are when running games or productivity applications from ROM cartridges. In fact, because

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2940-406: The full 32 KB of selected video RAM available at 0xB8000. This difference causes some software written for Tandy graphics not to work correctly on a PCjr, displaying images in 320 × 200 16-color or 640 × 200 with periodic black horizontal lines: a "venetian-blinds" effect. It is possible that software for the PCjr that relies on the memory wrap-around at address 0xBC000 will not work correctly on

3010-492: The home computer market with 26% of all microcomputers sold in 1983, second only to the much less expensive Commodore 64 . For a year before the PCjr's announcement, the computer industry discussed rumors of a new IBM product, code named "Peanut", that would repeat the PC's success. The rumors described Peanut as a home computer with 64 kB of memory that would be IBM PC compatible , benefit from IBM's service network and, at US$ 600 to US$ 1,000 , be less expensive than

3080-433: The keyboard and computer if the user wanted a more reliable connection, which also eliminated the need for batteries, since the keyboard IR receiver is automatically disabled when the cord is attached to the computer. The chiclet design was not well received, and in 1984 IBM began shipping a new design, still wireless, but using more conventionally shaped keycaps. The PCjr also has a light pen port. Besides being used for

3150-494: The machine was mixed. Ziff Davis , publisher of the successful PC Magazine , printed the first issue of PCjr Magazine before the first units shipped, and competing computer magazines included Peanut , PCjr World , jr , and Compute! for the PC and PCjr . However, as new information became available about the machine, retailers became deeply concerned about its marketability. When the PCjr became widely available in March 1984 sales were below expectations. Consumer interest

3220-406: The main system unit. The 5161 can be connected to either an XT or to the earlier 5150 (the original IBM PC). PC DOS 2.0 offers a 9-sector floppy disk format, providing 180K/360K (single- vs. dual-sided) capacity per disk, compared to the 160K/320K provided by the 8-sector format of previous releases. The XT was not offered in a floppy-only model for its first two years on the market, although

3290-478: The mainboard, and an additional 64 KB can be installed via a special card that plugs into a dedicated slot on the PCjr mainboard. This 64 KB or 128 KB of base RAM is special in that it is shared with the PCjr video subsystem. TGA video modes use either 16 KB or 32 KB of RAM. Text modes use 16 KB divided into 4 or 8 pages, for 80×25 or 40×25 text formats respectively; any part of the 16 KB not used for text display pages can be used as general RAM. In graphical modes,

3360-409: The market four days before IBM's announcement, after losing US$ 223 million in nine months against Commodore by selling its 99/4A for as low as $ 99 . Developers began creating PCjr software in 1982. Sierra On-Line , SPC , and The Learning Company were among those that produced games, productivity, and educational software as launch titles , using detailed IBM production outlines under

3430-788: The monochrome MDA and color CGA boards. PCjr graphics were similar to CGA, with several new video modes: The primary improvement over CGA is the greater color depth. CGA could only display 4 colors in its medium-resolution mode, and 2 colors in high-resolution. The PCjr increases these to 16 and 4 colors. Video modes on the PCjr use varying amounts of system memory: 40 x 25 text mode uses 1 KB, for instance, while 320 x 200 x 16 and 640 x 200 x 4 use 32 KB. These latter two modes, as well as 80 x 25 text mode, are referred to in documentation as "high bandwidth modes" and are unsupported on base models with only 64 KB of memory. Multiple text or graphics pages can be used for page-flipping as long as there

3500-490: The next-generation successor that some had anticipated. Compared to the original IBM PC, the XT has the following major differences: Otherwise the specifications are identical to the original PC. The number of expansion slots in the original IBM PC was a limiting factor for the product, since essential components (such as the video controller, disk controller and printer interface) each came as separate expansion cards and could quickly fill up all five available slots, requiring

3570-405: The number of colors in each screen mode. CGA's 2-color mode can be displayed with four colors, and its 4-color mode can be displayed with all 16 colors. Since the Tandy 1000 was much more successful than PCjr, their shared hardware capabilities became more associated with the Tandy brand than with IBM. While there is no specific name for the Tandy graphics subsystem (Tandy's documentation calls it

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3640-418: The original PC, the amount of physical space in the chassis differs, so two of the new slots (located behind the hard drive) cannot accept full-length cards. In addition, the spacing of the slots is narrower than in the original PC, making it impossible to install some multi-board cards. The 5161 is an expansion chassis using an identical case and power supply to the XT, but instead of a system board, provides

3710-688: The original XT and the XT/286 was discontinued in late 1987 after the launch of the IBM Personal System/2 (PS/2) line. The 8086-powered IBM PS/2 Model 30 served as the direct replacement for the XT in that PS/2 line. Unlike higher-end entries in the PS/2 line, which feature the Micro Channel expansion bus, the Model 30 contains 8-bit ISA bus slots, exactly like the XT. The XT was well received, although PC DOS 2.0

3780-431: The palette table to use any colors desired. Palette changes must be made during horizontal or vertical blanking periods of a video frame in order to avoid disrupting the display (transiently during the palette change). The monitor included with the PCjr is a 12" TTL RGBI display like those supported by the CGA, but including an internal amplified speaker. Also like CGA, the PCjr supported composite video out for use with

3850-512: The palette, without making any changes to the character attribute bytes in RAM. The PCjr/TGA programmable palette was carried over to the IBM EGA, where it was extended to 6-bit entries for 64 colors. VGA retained this 16 x 6-bit "internal palette" and added another, cascaded 256 x 18-bit RAMDAC "external palette". Unlike every other IBM-designed PC video standard, TGA uses some of the main system RAM as video RAM. The PCjr had 64 KB of built-in RAM on

3920-403: The process of switching video modes on the PCjr. Resetting the VGA, which must be done during certain video mode switches, must be done by code not running from the system RAM controlled by the VGA, and if the CRTC or the VGA is disabled for too long, the contents of the internal RAM can be lost. Additional external DRAM (in sidecar expansion modules) is refreshed independently and never affected by

3990-445: The same CPU and clock speed, performance is often inferior to the PC, because access to system RAM is delayed by wait states added by the Video Gate Array to synchronize shared access to RAM between the CPU and the video hardware. IBM claimed that an average of two wait states are added, but the designers of the Tandy 1000, a clone of the PCjr, claimed that six was a more accurate figure. This delay only applies to software resident in

4060-465: The same RAM-sharing scheme. The PCjr video and Tandy 1000 graphics subsystems are not identical. One difference is in the size of the video memory aperture at address 0xB8000. While the PCjr video hardware can use up to 32 KB of RAM for the video buffer, it emulates the CGA precisely by making only 16 KB of this available at address 0xB8000. Like the true CGA, the 16 KB of RAM at 0xB8000 is aliased at address 0xBC000. The Tandy hardware, in contrast, makes

4130-437: The side of the unit. Despite widespread anticipation, the PCjr was ultimately unsuccessful in the market. It was only partially IBM PC compatible , limiting support for IBM's software library, its chiclet keyboard was widely criticized for its poor quality and limited expandability, and it was initially offered with a maximum of 128  KB of RAM, insufficient for many PC programs. The PCjr came in two models: The PCjr

4200-455: The standard IBM BASIC with commands to support the new video and audio functionality. The system will boot into Cartridge BASIC if no cartridge or boot disk is present. The register mapping of the PCjr's video hardware is different from the IBM CGA card, so software that tries to modify or read registers directly will not work. The PCjr has a "gate" register to which software writes the number of

4270-422: The standard by which all other home computers are measured" and estimated sales of one million or more in 1984, expecting the PCjr to change the home-computer market in a similar way to how the IBM PC had changed the business-microcomputer market. They predicted that the PCjr would extend IBM's dominance, with customers able to use the company's computers in the home and in the office. Texas Instruments left

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4340-513: The standard ribbon cable with two floppy connectors was still included. At that time, in order to get a second floppy drive, the user had to purchase the 5161 expansion chassis. Like the original PC, the XT came with IBM BASIC in ROM . The XT BIOS also displays a memory count during the POST , unlike the original PC. The XT has a desktop case similar to that of the IBM PC. It weighs 32 pounds (15 kg) and

4410-468: The still officially nonexistent computer appeared. Software companies prepared to market products as "Peanut compatible" with the computer of which, rumors said, IBM would produce 500,000 units in the first year. Adweek estimated that IBM would spend $ 75 million on marketing, including an alleged license of Charles Schulz 's Peanuts characters. Smalltalk magazine in August published a detailed article on

4480-403: The user to swap cards in and out as tasks demanded. Some PC clones addressed this problem by integrating components into the motherboard to free up slots, while peripheral manufacturers produced products which integrated multiple functions into one card. The XT addressed the problem by adding three extra expansion slots for a total of eight. While the slots themselves are identical to those in

4550-407: The video area from address 0xB8000 through 0xBFFFF. The PCjr's video memory cannot be moved above 128k if expansion memory is added, so some PC software that ran off of self-booting disks would not work on a PCjr if the software required more than 128k of RAM. The floppy controller on the PCjr also had its I/O registers mapped into different ports than on the PC, and since the PCjr did not have DMA,

4620-424: The video register to be accessed, followed by the value to be written into it. Alteration of other CRTC registers cannot be assumed to produce the same results from the PCjr video system as from the CGA. Programs for the CGA that manipulate the CRTC start address, and that rely on address wrap-around above address 0xBC000, may not work correctly on the PCjr because it always has a 32 KB contiguous block of RAM in

4690-463: Was especially written to take advantage of the coprocessor would show a significant speedup. The power supply is 130 watts, an upgrade from the original PC. Those sold in the US were configured for 120 V AC only and could not be used with 240 V mains supplies. XTs with 240 V-compatible power supplies were later sold in international markets. Both were rated at 130 watts. IBM made several submodels of

4760-566: Was manufactured for IBM in Lewisburg, Tennessee by Teledyne . A related machine, the IBM JX , was sold in the Japan, Australia and New Zealand markets. The PCjr chassis is made entirely of plastic, unlike the all-steel chassis of the IBM PC. A 5.25" front bay allows the installation of a 180/360K floppy disk drive. The internal floppy drive was a half-height Qume 5.25" unit; IBM also used these drives in

4830-491: Was reportedly high until demonstration machines were available, at which point interest dropped steeply. Dealers reported that consumers disliked the price, keyboard, and limited memory, and retailers that sold primarily to business customers did not know how to market it. The press soon reported that the PCjr could embarrass IBM, with executives reportedly worrying about demand. Stores began discounts while vendors slowed plans to release products. IBM admitted that demand for

4900-539: Was supplied with Windows 2.0 , and could be used on Windows 3.0 . TGA graphics are built into the motherboards of Tandy computers. The PCjr uses a custom monitor with a unique 18-pin plug, but an adapter (with the same DE-9 connector and pinout as IBM's CGA/EGA ) can connect it to the IBM Color Display or similar 4-bit digital ( TTL ) RGBI monitor. The Tandy 1000 provides the DE-9 connector directly. The monitor

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