Category: Computers

IBM introduced the 8514 Display Standard in 1987; about the same time as VGA. The companion monitor (model 8514) was also sold by IBM. The pair (8514/A Display Adapter and 8514 monitor) comprise the 8514 Display Standard and is generally regarded as the first mass-market video card accelerator. It was certainly not the first in the industry, but others before it were largely designed for workstations. Workstation accelerators were programmable; the 8514 was not; it was a fixed-function accelerator and could therefore be sold at a much lower price for mass-market use. The card typically had 2D-drawing functions like line-draw, color-fill, and BITBLT offloaded to it while the CPU worked on other tasks.

The basic modes the 8514 were designed to operate at were…

1024×768 pixels at 256 colors and 43.5 Hz interlaced.
640×480 pixels at 256 colors and 60 Hz non-interlaced and other regular VGA modes. The 8514/A card was only responsible for the 1024×768 graphic mode. All other modes were created using the VGA hardware on the computer’s motherboard and then the video was fed through the adapter card to the monitor which was connected to the adapter card. 8514 did not support an 800×600 pixel mode even though you might think it could.
Note the difference between interlaced and non-interlaced display and the frequency above. While the 8514 displayed a much higher resolution screen than most other mass-market solutions of the day, the use of an interlaced display was unusual.

8514 was replaced by IBM’s XGA standard which we’ll talk about later on this page. For now, we’ll get back in sequence with VGA…

Noting the 720×350 resolution of the MDA display, a company called Hercules Computer Technology (founded by Van Suwannukul), in 1982, developed an MDA-compatible video card that could display MDA text as well as graphics by having routines to individually address each pixel in the display. Because the screen height had to be a multiple of four, the full resolution of the Hercules Graphics Card was 720×348.

The Hercules card addressed two graphic pages, one at B0000h and the other at B8000h. When the second page was disabled there was no conflict with other adapters and the Hercules card could run in a dual-monitor mode with CGA or other graphics cards on the same computer. Hercules even made a CGA-compatible card called the Hercules Color Card and later the Hercules Graphics Card Plus (June 1986) followed by the Hercules InColor Card (April 1987) which had capabilities similar to EGA cards.

The graphics caught on and not only did Hercules cards multiply rapidly but clones of them started to appear; the ultimate homage to success. Most major software included a Hercules driver.

However, despite its attempts to keep up, Hercules started to fail as a company and was acquired by ELSA in August 1998 for $8.5 million. ELSA then declared bankrupcy in 1999 and the Hercules brand was bought by Guillemot Corporation, a French-based company, for $1.5 million. In 2004 Guillemot stopped producing graphic cards but Hercules, the name, lives on in some of their software and other products.

But, color was still the ultimate goal and Hercules was pushed out by other IBM specifications…

The Enhanced Graphics Adapter was introduced by IBM in 1984 as the primary display for the new PC-AT Intel 286-based computer. EGA increased resolution to 640×350 pixels in 16 colors. The card itself contained 16 KB of ROM to extend the system BIOS to add graphics functions. The card started with 64 KB of video memory but later cards and clone cards came with 256KB of video memory to allow full implementation of all EGA modes which included…

High-resolution mode with 640×350 pixel resolution. On any given screen display a total of 16 colors could be displayed; however, these could be selected from a palette of 64 colors.

CGA mode included full 16-color versions of the CGA 640×200 and 320×200 graphics modes. The original CGA modes were present in the card but EGA is not 100% hardware-compatible with CGA.

MDA could be supported to some degree. By setting switches on the card an MDA monitor could be driven by an EGA card however only the 640×350 display could be supported.

Some EGA clones extended the EGA features to include 640×400, 640×480, and 720×540 along with hardware detection of the attached monitor and a special 400-line interlace mode to use with older CGA monitors. None of these became standard however.

EGA’s life was fairly short as VGA was introduced by IBM in April of 1987 and quickly took over the market. In the meantime, IBM had a brief go with a specialized graphics system called PGC and the 8514 Display Standard…

Introduced in 1981, MDA was a pure text display showing 80 character lines with 25 vertical lines on the screen. Typically, the display was green text on a black background. Individual characters were 9 pixels wide by 14 pixels high (7×11 for the character, the rest for spacing). If you multiply that out you get a resolution of 720×350 but since the individual pixels were not capable of being addressed there were no graphics. Although, some programs managed some interesting bar charts and line art using various ASCII characters; particularly those above 128 used by code page 437.

The IBM MDA card had 4 KB of video memory. Display attributes included: invisible, underline, normal, bright/bold, reverse video, and blinking. Some attributes could be combined. IBM graphic’s card also contained a parallel printer port giving it the full name: Monochrome Display and Printer Adapter.

The monitor’s refresh rate was 50 Hz and users tended to complain about eyestrain after long days in front of the monitor.

A Computer Power Supply (PSU) is vital to the operation of a computer. The Power Supply converts AC current to DC current and then sends power to all of the internal components in the computer system so they can function.

A Computer Power Supply is a metal box usually located inside the top backside of the computer case. The power supply is visible from the back of the computer.

It is easily identified by the presence of a port for the power cable. There are three typical voltages used in a power supply: 3.3 volts, 5 volts, and 12 volts. The 3.3 and 5 volt supplies are usually used by digital circuits, while the 12 volt supplies are more typically used to supply power to fans, motors, and disk drives.

The main specification of a power supply is in watts. Most PC’s today use a push button switch on the front of the computer case to power up the computer. This push button sends a 5 volt signal to the power supply letting it know it is time to send power to all of the internal computer components. To shut the computer down most computers have a “shut down” option located in a menu bar. When this is used the operating system sends a signal to shut the computer down. The Power supply also has a 5 volt circuit of “standby voltage”, known as VSB. This circuit is used so even when the computer is turned off, the push button to start up the computer will still work (enabling the computer to turn on). There are different types and styles of power supplies on the market today. Three of the basic types of desktop PC power supplies are AT, ATX and ATX-2.

AT Power Supply – Typically used in older PC’s

ATX Power Supply – Commonly used in PC’s today

ATX-2 Power Supply – New standard for power supplies today

Power supplies are easily changed and are generally cost effective. If you are going to change a power supply make sure you get one with room for expansion so you are prepared for the future.