Classic Computer Magazine Archive CREATIVE COMPUTING VOL. 10, NO. 3 / MARCH 1984 / PAGE 74

IBM PCjr. (evaluation) Thomas V. Hoffmann.


There is an old saying that the more things change, the more they remain the same. In 1981 when Will Fastie first looked at the IBM PC for this magazine, he described his first encounter of the close kind this way:

I entered the contemporary but unremarkable building . . . Jeannette Maher of the Public Relations Department escorted me . . . through a tastefully decorated lobby and through smoked glass doors set in a wall of smoked glass. Inside . . . and there they were. Three IMB Personal Computers sat on three modular display stations.' Then he began to drool. (You can look it up).

Two years later, my first trip to Boca Raton was like visiting D[ej a Vu City. Jeannette is no longer the sole PR person, but the tasteful lobby, smoked glass (now sporting a splashy neon object de signage), modular display stations, and three PCs were all there, just as Will described. Suprise! No PCjrs, not even a peanut shell on the floor.

Blind Man And Dancing Elephants

The good old days, when reviewers were ushered into the sedate presence of the original PC, have given way to more participatory modern times. The juniors were upstairs in someone's office.

We carted the stuff downstairs, cast aside the old PCs, and began setting up the juniors. The operation was totally trivial: open the box, attach the power cord to the system unit, attach a monitor to the appropriate connector, put batteries in the keyboard, and turn on the system--less than five minutes from box to operation, and only one third more calories than attaching a video game to a TV set. The PCjr might also be called IBM Lite--it weights less than nine pounds with disk drive, and you can hold it in one hand and wave it around. (Yes, I did, and no, I don't know why. It seemed reasonable at the time.)

So just what is this PCjr? Is it a cheap PC or an expensive game machine? Who is it for? Where will it be used: home, office, classroom? How expandable is it? How compatible with its older siblings? Is it worth the price? The answers depend, of course, on one's point of view.

It is definitely a PC, extremely compatible with its IBM predecessors, and significantly less expensive (about half the cost of a similarly configured original PC). The enhanced graphics and sound features make it a better machine for games and animation than the bigger PCs, but there are better and less expensive game machines. The real strength of the PCjr is that it is an IBM PC in every respect: same processor (the Intel 8088), same operating system (PC DOS), identical disk formats, and compatible displays. The basic unit includes several features that are extra cost options on the big PCs: the video display adapter, serial port, and joystick adapter are all built in.

What, no bad news? Only a little: the PCjr is somewhat slower than previous IBM PCs, it can't support the 8087 arithmetic processor, and the current limitations on memory and disk may prevent the use of some large programs and data files. The speed difference is attributable to the design of the video display and RAM memory system, and is permanent. The other limitations, except for the absence of the 8087, are almost certainly temporary. The architecture of the PCjr will support considerable expansion; IBM and other manufacturers will certainly offer a wide variety of options. Many will probably be available within weeks of the first deliveries of PCjrs.

First Impressions

The PCjr is both more and less than the standard PC. Like the original IBM PC (now called PC1) it consists of two major components, a system unit and a keyboard, to which a display must be added to make a complete computer. The most striking difference between the junior and its predecessors is purely physical: it is much smaller.

At 14 wide by 11.5 deep by 3.5 high the system unit occupies only 43 percent of the volume of the PC1. The reduction in weight is even greater due to the plastic case (the others have metal cases) and external power transformer (sort of a giant AC adapter.)

The 62-key wireless keyboard is perhaps the most innovative feature of the PCjr. It is powered by four AA batteries and communicates with the system unit over an infrared serial link with a range of up to 20 feet. An optional (i.e., extra cost) cable is available to connect the keyboard directly to the system unit. When connected by the cable, the keyboard is powered directly from the system unit, and the infrared system is disabled. This conserves batteries and eliminates interference among multiple systems in the same vicinity, as might occur in a classroom, for example. The cable may also be necessary to avoid interference with other infrared devices such as TV remote controls, in the home.

Another innovation, for IBM at least, is the provision for ROM program cartridges. Each cartridge contains 32K of ROM, but is quite a bit smaller than traditional video game cartridges. While there will be few programs available in this format initially, cartridges offer several significant advantages. They are much more rugged and reliable than disk and cassette tapes, and are safer and easier for children to use. There is no loading time; the programs are instantly available when the cartridge is plugged in. Furthermore, since the cartridge programs can execute directly from ROM they leave all the RAM available for data storage.

Finally, cartridges offer greater immunity to casual software piracy, so vendors may be more likely to charge reasonable prices per copy for programs. (It has been estimated that for many popular programs, illegal copies in use vastly outnumber the legitimate ones. This undoubtedly raises software prices as vendors try to compensate for "free' copies.)

System Unit

The system unit is a marvelous example of low cost construction that never looks cheap, just inexpensive. It consists of a plastic box with a snap-on top cover. Inside, the main printed circuit card is mounted flat against the bottom, resting on snap-on plastic studs. There are four dedicated connectors for the power regulator, memory expansion, internal modem, and disk adapter cards, which mount vertically. The on/off switch and the connector for the power cord (from the external step-down transformer) are mounted directly on the back of the power regulator card, and are accessed through openings in the outer case. The modem card has a standard modular telephone jack and a matching hold in the rear panel. All other peripheral and expansion connectors are mounted directly on the main system card and align with openings in the outer case.

The only two screws (actually bolts) in the box hold the disk drive in place. Everything else snaps in and out with bare hands: inexpensive to assemble, easy to upgrade or repair. It is a good bet that IBM has plenty of room for price reductions, should competitive pressures require them.

The main system board is about 11 by 14 and contains the following major elements:


There are two models of PCjr available. The entry system lists for $669 and includes the wireless keyboard and system unit with 65K RAM and all the interfaces listed above. The enhanced system is $1269 and comes with an additional 64K of user RAM for a total of 128K, a disk adapter, and one halfheight 5 1/4 double sided, double density disk drive with a capacity of 360K, all mounted inside the system unit.

The entry version can be upgraded to the enhanced version at any time by plugging in the RAM expansion card and disk drive and adapter. The two-step approach costs only $20 more than buying the pre-packaged enhanced system.

The connectors for peripheral devices, such as serial printer, high-resolution display, and joysticks, are not the usual 9- and 25-pin D connectors usually found in small computers. The PCjr uses rectangular arrays of pins, similar to those used for flat cable connectors on PC cards, soldered directly to the main systems board. Special adapter cables are available for each device, where appropriate, to convert to industry standard D connectors. This lowers the cost of the system unit, but adds an occasional $20 or $30 for adapter cables for displays (essential) and serial devices.

The disk drive, manufactured by Qume, is mounted horizontally in the upper right corner of the system unit, right above the two cartridge slots. It is half the height of a standard 5 1/4 mini-floppy drive, and very slightly slower due to longer head settling times. The difference is hardly noticeable.

In a standard minifloppy drive you insert the disk and flip down a hinged door to engage the drive spindle and read/ write head. On the PCjr you rotate a lever counter--clockwise to engage the mechanism; the same lever blocks the entry slot so the disk can't be removed until the lever is flipped back. I found the lever mechanism easy to use, once I overcame my instinctive groping for the flip-down door. If you have never used a standard floppy, there may be no instincts to overcome.

The 360K capacity of the floppies is identical to the PC1 and PC/XT, and quite a bit greater than most other "home' computers in this price range, where single sided, single density drives of about 100K are the norm.


The PCjr keyboard has generated a fair bit of controversy. IBM calls the 62-key unit "a cordless, portable, hand-held device [utilizing] full travel, carbon contract/rubber dome technology for long wear and reliability.' Critics say it is a cheap, "Chiclet' keyboard, unworthy of a "real' computer, with the wireless business a superfluous gimmick. Who is right? Ask the blind man over there by the elephant.

If you are a fast touch typist word processing freak with big fingers, forget it; this is no "heads down, smoking fingers' professional data entry keyboard. But it is not supposed to be. Neither is it like pressing a box of Chiclets into your lap. The keys move up and down; they click; you can feel them hit bottom. More important, they are all in the right places (assuming you agree that QWERTY is "right'). I like the standard PC keyboard very much, but after about 45 minutes I was quite comfortable with the junior version. Once my fingers learned the spacing (the keys are a little closer together than on a standard keyboard) and developed the right rhythm, even word processing wasn't uncomfortable.

Rhythm is important for another reason. Since the PCjr has no DMA capability, disk reading and writing require the total attention of the processor. (In the previous PCs, the DMA facility allows data transfers to and from the disk to occur directly to memory, without processor intervention.) To insure correct disk transfers, the keyboard interrupt is disabled during the actual data transfer, with the result that an occasional keystroke may be lost. Instead of the desired effect, you hear a beep signalling the ignored key (well, it is better than nothing). The problem is worst during periods of intense disk activity, such as loading programs or updating files. It is best to learn to avoid typing during these times; the beeps help a lot.

Game players, slouchers, and other relaxed individuals will find the cordlessness a godsend. There is nothing to stretch or break. Tabletop users have a choice of two tilt angles with two little flip-down legs on the underside of the keyboard. The dust-and spill-resistance should be quite high, since the entire interior is covered by a solid rubber sheet with molded-in domes.

Glued to the underside of each dome is a little piece of carbon. When you press a key, it squishes the dome, the carbon makes contact with the underlying printed circuit card, and the keystroke is sensed by the keyboard microprocessor, which transmits the information to the system unit--simple, reliable, and cheap.

Enough about the feel. How does it look, and how can 62 keys do the work of 83? The key legends are not printed directly on the keytops, but on the surrounding bezel directly above and below the keytops, an obvious cost reduction. The legends above are white on a tan background, and a little hard to see because they are small and the colors don't contrast well. This is no problem for touch typists, but little kids and myopic adults may have problems.

The standard PC keyboard has 83 keys, the PCjr only 62. What is missing? The ten function keys on the left of the standard keyboard are gone. Instead, a new FUNCTION SHIFT key has been added to the upper right side. To generate a function code, depress the FUNCTION SHIFT key (surrounded by a green box), then the corresponding numeric key in the top row (1 through O). For SHIFT, CONTROL, and ALTERNATE shift combinations, the same procedure applies; first hold down the FUNCTION SHIFT, then press the desired combination. This sounds much worse than it really is. The technique is entirely consistent, logical, and obvious. Furthermore, the smaller size of the PCjr keyboard makes even the four-key combinations easy to accomplish with normal-sized hands. Three-year-olds won't make it, but they probably don't know about CONTROL-SHIFT-F5 anyway.

The separate numeric pad is also gone, as are the numeric lock and scroll lock keys, backslash, tilde, and right- hand plus and minus. The four cursor keys remain, with home, page up, page down, and end achieved via the FUNCTION SHIFT key. The other keys are also replaced by ALTERNATE or FUNCTION SHIFT combinations, with reasonable mnemonic value. For example, FUNC-S is scroll lock, and FUNC-B is break. These new meanings are marked below the appropriate keys, in white-on-green for FUNC and white-on-red for ALT.

If the foregoing leaves you totally disgusted, don't despair. The PCjr has provisions for an 83-key keyboard. If IBM doesn't offer one soon, it is certain that third party keyboard manufacturers will.


In addition to the simple tone generator from the Older PC3, the PCjr has a sound generator chip with three independent channels, or voices, each with independent attenuation (volume control), plus a noise generator. Music in three-part harmony, explosions, and other neat effects are possible with the right programming. The extended Basic cartridge includes statements to support these enhanced sound capabilities.

The audio output is available at the rear of the system unit. With an external amplifier and speaker (or home stereo or tape deck) connected to the audio output jack, you can play to the whole neighborhood, record for posterity, or do other creative audiophile kinds of things. Even more interesting is the audio input line in the external I/O expansion bus, which can be mixed with the internally generated sound. Can add-on speech synthesizers be far behind? Daisy, Daisy . . .

Video Displays

The video display system in the PCjr is a direct descendent of the original PC color graphics adapter, with three significant improvements. First, most of the logic on the old card has been put in a single custom integrated circuit; what was previously a whole circuit board is now two big chips and a few little ones, and included in the basic price (instead of being a $244 "mandatory option'). Second, the entire 128K of user RAM can be used for video storage; previously only 16K on the video card was available. This allows many more "pages' or images to be kept in memory and switched rapidly to the display--good for quick help screens, animation, and the like. Third, the color capability has been improved significantly.

The old PCs could display 320 by 200 dots in four colors (medium resolution), or 640 by 200 dots in two colors (high resolution). Unfortunately, in high resolution one of the colors was always black, and in medium resolution the color choice was limited, confusing, and a little ugly. The PCjr makes two important enhancements: independent choice of graphic resolution (160, 320, or 640 dots wide) and color resolution (16, 4, or 2 colors), and a completely general color palette. The high resolution 16-color mode would consume all 128K of memory, and thus could be reasonably used only by a cartridge program.

The color palette allows an arbitrary choice of any of the 16 possible colors to be assigned in any mode. The result is a much more flexible all-points-address- able color graphics system, much better suited to pictorial displays for games and educational programs. In other words, it looks much better and is more fun.

There is support in Basic for the enhanced color modes as well as the standard (i.e., old PC) graphics and 40- and 80-column alphanumeric display modes. The PCjr has the same 256-character display set as the previous IBM PCs. The designers have gone to considerable trouble to make the new hardware compatible with most of the software tricks that existing PC programs have used in display generation, and they have done an excellent job.

The PCjr does not support the high- resolution IBM monochrome display. There are provisions for connecting high-resolution RGB color monitors (via a $20 adapter cable), composite video monitors (via a standard RCA phono plug), and television sets (via a $30 cable including an RF modulator). The TV connection also sends the audio output to the set, where it can be adjusted with the volume control knob.


There are currently four hardware options available for the PCjr: the 64K Memory and Disply Option ($140), the Disk Drive and controller ($480), the Internal Modem ($199), and the Parallel Printer Attachment ($99).

The memory option brings the user RAM memory up to 128K and allows full use of the display features. I recommend the full memory expansion even for systems without disks.

The internal modem, made by Novation, is a full-featured smart modem for 110 and 300 baud communications. The modem card contains its own serial interface device, so the standard serial port is still available for attaching a printer or other device. The Modem supports automatic dialing (pulse or tone) and answering, with error detection and diagnostics supplied in the system ROM.

The parallel printer attachment attaches to the 60-pin I00o channel expansion connector on the right side of the system unit. The attachment is required to support standard paralled printers such as the IBM Graphics Printer, Epson, Oki, and others. The I/O channel is passed through so that further options may be attached, always moving rightward. The current power supply will support up to five attachments on the I/O channel, plus the internal disk and modem.

The PCjr ROMs have provisions for handling "non-Keyboard scan codes' arriving through the infrared link. Speculation about wireless joysticks received an immediate "we can't comment on that' response from IBM people in the vicinity, who then taunted us about the mysterious connector marked L on the rear panel. They said it stands for "later.' Stay tuned.


The built-in 64K ROM contains diagnostics, hardware I/O routines (BIOS) used by Basic, and the disk operating system, and the cassette Basic interpreter, PCjr cassette Basic is essentially the same as the standard PC cassette Basic: the essential features of the language plus program and data files on casette tapes.

Advanced Basic features are provided in the PCjr Cartridge Basic ($75), which plugs into either of the two ROM cartridge slots in the front of the system unit. The 32K ROM cartridge augments the standard cassette Basic with advanced graphics, sound and music, communications support (including a terminal emulator), and disk I/O (with DOS 2.1). The resut is a superset of the standard PC advanced Basic, which requires disk and DOS and is partially RAM resident, all in ROOM DOS is required quired only if you want to use disk files.

DOS version 2.1 is the recommended disk operating system for the PCjr. (Earlier versions seemed to work as well, but IBM will support only version 2.1 and beyond.) DOS 2.1 has the same function and storage requirements as DOS 2.0, and runs on the PC1 and PC/XT as well as the PCjr. the major difference is that Basic and BasicA require Cartridge Basic on the PCjr as a prerequisite. If the cartridge isn't plugged in, disk Basic won't run. Most of the utility programs supplied with DOS are identical in versions 2.0 and 2.1; the few that are different seem to have had some minor bug repairs made, but there are nosignificant enhancements.

There are four game cartridges available for the PCjr: Crossfire, Mine Shaft, Mouser, and ScubaVenture. Other software is available on disk: Logo, Macro Assembler, Basic Compiler, Multiplan, VisiCalc, HomeWord, EasyWriter, WordProof, and dozens more. Many, if not most, of the disk software packages for the PCjr are identical to those for the PC1 and PCXT. In some cases, only the latest versions will work on all three machines. Dealers will have a complete list of IBM-produced or distributed software compatible with the PCjr.


Whether any given piece of software is compatible with the PCjr is hard to predict with certainty, but there are a few simple considerations to take into account. The most obvious are the current disk and memory limitations of one 360K disk and 128K of user RAM. The single disk will function as two logical drives, A: and B:, with the system prompting the operator to change disks when necessary.

For some applications, this is acceptable. For others, it is ridiculous. For example, if a program copies data from one disk to another one record at a time instead of in big blocks, thousands of insertion/removal/insertion cycles might be required. Logically, it works; physically, you should live so long.

Memory use is a little more complicated. The 128K of system memory must accommodate the 16K video display buffer and 24K for DOS, leaving only 88K for user programs (24K is a 64K system). Some programs are simply too big; they won't fit and you will get an error message from the DOS loader. Others may load, but have insufficikent working storage; the good ones will tell you about, it the bad ones will go ahead any try to run anyway. Then there is the middle ground: programs that work, but with limits that may or may not be acceptable. Do you need more than 200 entries in your spreadsheet or 85 statements in your assembler program? Try before you buy.

Programs, such as APL, that require the 8087 will never work in the PCjr. Programs that make assumptions about the length of time a sequence of instructions should take may not work, since the PCjr is slower in accessing the user RAM. Programs that directly access some devices (especially the disk and display systems) also may not work. Some software copy protection schemes might fall into these traps.

In general, programs that follow the rules of BIOS or DOS for device access, don't require more memory than is available, and don't need hardware that isn't there (like the monchrome display), will run without change on the PCjr.


I like this machine very much. For the home, its graphics and sound features provide a good base for high quality, enjoyable games and educational software. Its compatibility with the PC1 and PCXT make it ideal for occasional work-at-home use, sharing programs and data with the machine at the office.

The PCjr makes sense for the office, too, as a PC-compatible spreadsheet workstation, programmable telecommunications terminal, or wherever the higher cost standard PC isn't quite justifiable. It is a great machine for schools as well--at all levels. From Ogo for the little ones, through introductory computer architecture for college classes, the PCjr is a credible vehicle for serious education with or about computers.

For myself, I would love to have one right now. Instead of sitting upstairs in my cold den, typing fast to keep my fingers from stiffening from the cold air flowing through the gaps around my storm windows, I could be downstairs, comfortably nestled on the couch, with a roaring fire in the fireplace, warmly, leisurely, cordlessly processing these final words. But then I might never finish.

Table: Prices and Configurations

Here is a quick summary of the prices for representative PCjr hardware and software components, and some typical configurations.

Photo: PCjr under the hood.

Photo: The PCjr system unit atop a standard PC system unit. The round opening is the infrared receiver for the cordless key board. The two ROM cartridge slots are directly under the half-height disk drive.

Photo: The standard PC 82-key keyboard and the PCjr 62-key cordles keyboard. Though it has fewer keys, the PCjr keyboard can generate the same codes as the standard keyboard by using the special function shift key in the upper right corner in combination with other keys.

Photo: Interior of the PCjr keyboard. The microprocessor, infrared diodes, and cable connector are on the printed circuit board at the top of the photo. The rubber sheet at the bottom covers the circuit board. Note the carbon pieces on the underside. In the center is the top cover, which holds the plastic keytops.

Products: IBM PCjr (computer)