computer science

Professional Graphics Controller

Professional Graphics Controller is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Professional Graphics Controller rather than just read about it. In short: Professional Graphics Controller (PGC, often called Professional Graphics Adapter and sometimes Professional Graphics Array) is a graphics card manufactured by IBM for PCs. It consists of three interconnected PCBs, and contains its own processor and memory.

Key takeaways

Professional Graphics Controller belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Professional Graphics Controller to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Professional Graphics Controller from memory before moving on to harder problems.

Reference excerpt

Professional Graphics Controller (PGC, often called Professional Graphics Adapter and sometimes Professional Graphics Array) is a graphics card manufactured by IBM for PCs. It consists of three interconnected PCBs, and contains its own processor and memory. The PGC was, at the time of its release, the most advanced graphics card for the IBM XT and aimed for tasks such as CAD. It was designed and manufactured for IBM by Vermont Microsystems, a start-up company founded by ex-IBM employees.

Specifications Introduced in September 1984, the Professional Graphics Controller offered a maximum resolution of 640 × 480 with 256 colors on an analog RGB monitor via a DE-9 connector, at a refresh rate of 60 hertz—a higher resolution and color depth than CGA and EGA supported. This mode is not BIOS-supported. It was intended for the computer-aided design market and included 320 KB of display RAM and an on-board Intel 8088 microprocessor. The 8088 ran software routines for 2D and 3D graphics such as "draw polygon" and "fill area" from an on-board 64 KB ROM so that the host CPU didn't need to load and run these routines itself. While never widespread in consumer-class personal computers, its US$2,995 (equivalent to $9,300 in 2025) list price, plus $1,295 display, compared favorably to US$50,000 dedicated CAD workstations of the time (even when the $4,995 price of a PC XT Model 87 was included).

Development The Professional Graphics Controller was developed by Winooski-based start-up company Vermont Microsystems. Founded by two ex-IBM employees, VMI won a competitive bid to develop IBM's next-generation graphics adapter for the IBM PC in 1983. Their partnership resulted in the PGC, designed to allow the PC to run CAD/CAM software in high resolution and color depth. The PGC was principally designed by Curtis Priem, then a recent hire of VMI who later co-founded Nvidia in 1993. While IBM initially only wanted VMI to design the PGC while leaving manufacturing to IBM, Richards refused to agree to the bid unless IBM also allowed VMI to manufacture the cards as well. In a move described as uncharacteristic by The Wall Street Journal, IBM agreed to these terms. The PGC was discontinued in 1987 with the arrival of VGA and 8514.

Software support The board was targeted at the CAD market, therefore limited software support is to be expected. The only software systems known to support the PGC are IBM's Graphical Kernel System, P-CAD 4.5, VersaCAD, Canyon State Systems CompuShow and AutoCAD 2.5.

Output capabilities

PGC supports:

640 × 480 with 256 colors from a palette of 4,096 (12-bit RGB palette, or 4 bits per color component). Color Graphics Adapter text and graphics modes. Text modes use a font with 8×16-pixel character cells and have 400 rows of pixels. There are six possible color arrangements:

Default 256-colour palette - Low 4 bits intensity, high 4 bits colour; 16-colour palette - Makes the PGC behave as two 16-colour planes. If high 4 bits are 0, low 4 bits are colour; otherwise, high 4 bits are colour; 2-3-3 palette (Palette 2) - Bits 6-7 red, bits 3-5 green, bits 0-2 blue; 3-2-3 palette (Palette 3) - Bits 5-7 red, bits 3-4 green, bits 0-2 blue; 3-3-2 palette (Palette 4) - Bits 5-7 red, bits 2-4 green; bits 0-1 blue; 6x6x6 colour cube - six equally spaced shades of red, green, and blue.

Operation The display adapter was composed of three physical circuit boards (one with the on-board microprocessor, firmware ROMs and video output connector, one providing CGA emulation, and the third mostly carrying RAM) and occupied two adjacent expansion slots on the XT or AT motherboard or the Expansion Unit; the third card was located in between the two slots. The PGC could not be used in the original IBM PC without the 5161 Expansion Unit due to the different spacing of its slots. In addition to its native 640 × 480 mode, the PGC optionally supported the documented text and graphics modes of the Color Graphics Adapter, which could be enabled using an onboard jumper. However, it was only partly register-compatible with CGA.

Related monitor The PGC's matching display was the IBM 5175, an analog RGB monitor that is unique to it and not compatible with any other video card without modification. With hardware modification, the 5175 can be used with VGA, Macintosh, and various other analog RGB video sources. Some surplus 5175s in VGA-converted form were still sold by catalog retailers such as COMB (Close Out Merchant Buyers) as late as the early 1990s.

DE-9 video connector

The DE-9 connector used on the IBM Professional Graphics Controller (PGC) was a 9-pin connector like the Color Graphics Adapter (CGA) and Enhanced Graphics Adapter (EGA) but was otherwise a (would later become) VGA-compatible RGB signal. Significantly, early NEC MultiSync monitors had a 9-pin male port on the back with this pinout. This was used in some early VGA and VGA-compatible hardware because the standard pre-existed VGA. It is also found in some industrial hardware from the era. This "9-pin VGA" lacks several pins compared to full VGA, which was usually not problematic because the autodetection features supported by those pins only evolved over time, and prior to Windows 95, there was no user expectation of graphics cards and displays being fully plug and play. DE-9 "VGA" connectors generally all used the same pinout, and adapters to the DE-15 standard have been made. Ultimately all VGA hardware makers switched to standard DE-15 connectors, relegating the early variant to relative obscurity. DE-9 is the same physical size as DE-15, the latter being a high density configuration in the same "E" shell.

Hardware derivatives Matrox PG-640, PG-1280, QG-640 (for the DEC MicroVAX), VG-640 (VME) Dell NEC MVA-1024 card Everex EPGA Orchid Technology TurboPGA Vermont Microsystems IM-640, IM-1024

See also List of defunct graphics chips and card companies PC/GX Timeline of early 3D computer graphics hardware

Notes

References

Notes

External links Professional Graphics Controller: Notes - Pictures and programming information

Illustrations

Worked examples

Example 1 — a first encounter with Professional Graphics Controller

Start with the simplest possible case. Write down what Professional Graphics Controller claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Professional Graphics Controller before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Professional Graphics Controller ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Professional Graphics Controller

In research: Professional Graphics Controller appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Professional Graphics Controller in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Professional Graphics Controller is common in secondary-school and first-year university syllabi. It links to neighbouring topics Computer-related introductions in 1984, Display technology, Graphics cards, so understanding it makes those chapters shorter.
In everyday life: Look for Professional Graphics Controller outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Professional Graphics Controller in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Professional Graphics Controller means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Professional Graphics Controller out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Professional Graphics Controller in simple terms?

Why does Professional Graphics Controller matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Professional Graphics Controller?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Professional Graphics Controller.