Appearance: UsedFunctionality: WorkingDescription:============Similar to pictured,an IBM Mono / Printer Card. Part number 1501986, 1501985XM. These cards shippedwith IBM PC, XT, and AT systems. Should work in any 8-Bit ISA computer.Warranty and Returns:=====================We understand thatthere may be compatibility issues, space constraints, or it just doesn’t lookperfect. This item can be returned within 14-days for ANY reason. However,shipping to and from is not refundable. Shipping:=========- Local pickup isalso available at no cost.- Most orders placedbefore 9am will ship the same day.About Us:=========The ComputerPreservation Group is dedicated to the preservation of historical computers. Tohelp fund ongoing operations, select items are made available. To learn more,please visit our website: www.computerpreservation.com. Thank you for your support!Stock#:4062Details from http://en.wikipedia.org/wiki/IBM_Monochrome_Display_Adapter:The MonochromeDisplay Adapter (MDA, also MDA card, Monochrome Display and Printer Adapter,MDPA) introduced in 1981 was IBM's standard video display card and computerdisplay standard for the PC. The MDA did not have any pixel-addressablegraphics modes. It had only a single monochrome text mode (PC video mode 7),which could display 80 columns by 25 lines of high resolution text charactersor symbols useful for drawing forms.The standard IBM MDAcard was equipped with four kilobytes (kB) of video memory. The MDA's highcharacter resolution (sharpness) was a feature meant to facilitate business andwordprocessing use: Each character was rendered in a box of 9×14 pixels, of which8×14 made out the character itself (the other pixels being used for spacebetween character columns and lines). Some characters, such as the lowercase"m", were rendered eight pixels across.The MDA featured thefollowing character display attributes: invisible, underline, normal, bright(bold), reverse video, and blinking; some of these attributes could becombined, so that e.g., bright, underlined text could be produced.[1]The theoreticaltotal screen display resolution of the MDA was 720×350 pixels. This number isarrived at through calculating character width (nine pixels) by columns of text(80) and character height (14 pixels) by rows of text (25). However, the MDAagain could not address individual pixels; it could only work in text mode,limiting its choice of display patterns to 256 characters. Its character set isknown as code page 437. The character patterns were stored in ROM on the card,and so could not be changed by software. The only way to simulate"graphical" screen content was through ASCII art.Because of the lackof pixel-addressable graphics, MDA owners could not play most graphics-basedgames. At least one game, IBM's One Hundred And One Monochrome Mazes("Amazing fun for the whole family"), required MDA.[2] Code page 437included the standard 127 ASCII characters but also another 127 characters likethe aforementioned characters for drawing forms. Some of these shapes wouldlater show up in Unicode as box-drawing characters. The characters were alsoused in early PC games such as early BBS door games, or games like CastleAdventure by Kevin Bales.IBM's original MDAincluded a parallel printer port (hence its original name of "MonochromeDisplay and Printer Adapter"), thus avoiding the need for a separateparallel interface on computers fitted with an MDA.Outputcapabilities[edit]Characters of codepage 437Text modes:80×25 characterswith a 8×14 pixel font (effective resolution of 720×350)4 intensity levelcombinations (for text and background) for each character cellSpecifications[edit]Connector[edit]Pin numbers (lookingat socket):DE9 Diagram.svgPin assignments[3]PinFunction1 Ground 2 Ground 3 Not Used 4 Not Used 5 Not Used 6 Intensity 7 Video 8 Horizontal Sync(+) 9 Vertical Sync (-) Signal[edit]TypeDigital, TTL Resolution720h × 350v H-freq18.432 kHz V-freq50 Hz Colors1 Color Intensity2-4[4] Early boards[edit]Early versions ofthe MDA board had hardware capable of outputting red, green and blue TTLsignals on the normally unconnected video connector pins, theoreticallyallowing an 8-color display with a suitable monitor. The registers also allowthe monochrome mode to be set on and off. Yet there was no software to actuallycontrol that feature.[5][6][7]
