IBM Monochrome Display Adapter: Difference between revisions
Add {{Infobox computer peripheral}} per RTC_Style_Guide.md — peripheral pages must use the peripheral infobox |
Rewrite with verified information only — remove fabricated part numbers (CGA 1501486, MDA 1501481, FDD Adapter 1501507, Fixed Disk Adapter 6181682, Model F dimensions/weight), remove placeholder image filenames, replace speculative capacitor designator table with verified minuszerodegrees.net source data (all tantalums marked C7, 10µF/16V), fix 5150 dimensions/weight to 20x16x5.5 inches / 21-28 lbs, fix Model F dimensions/weight to 19x9x1.5in / 7lb4oz / 3.3kg. Per Joshua's feedback: never pub... |
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{{Infobox computer peripheral | {{Infobox computer peripheral | ||
| name = IBM Monochrome Display Adapter | | name = IBM Monochrome Display Adapter | ||
| image = [[File:IBM MDA | | image = [[File:IBM MDA card.jpg|260px]] | ||
| caption = | | caption = IBM PC Original Monochrome Display and Parallel Printer Adapter (MDA) | ||
| manufacturer = IBM | | manufacturer = IBM | ||
| type = ISA video display adapter (text only) with integrated parallel printer port | | type = 8-bit ISA video display adapter (text only) with integrated parallel printer port | ||
| release_date = | | release_date = 1981 (with the original IBM PC) | ||
| interface = 8-bit ISA | |||
| interface = 8-bit ISA | |||
| compatible = [[IBM PC (5150)]], [[IBM PC XT (5160)]], [[IBM PC AT (5170)]], PC-compatible clones | | compatible = [[IBM PC (5150)]], [[IBM PC XT (5160)]], [[IBM PC AT (5170)]], PC-compatible clones | ||
| connectivity = DB-9 TTL monochrome (drives the [[IBM 5151]]); DB-25 Centronics parallel (LPT1) | | connectivity = DB-9 TTL monochrome (drives the [[IBM 5151]]); DB-25 Centronics parallel (LPT1) | ||
}} | }} | ||
The '''IBM Monochrome Display Adapter''' ('''MDA''') is the original 8-bit ISA monochrome text adapter IBM released alongside the [[IBM PC (5150)]] in 1981. Unlike the [[IBM Color Graphics Adapter|CGA]], the MDA has '''no graphics modes''' — it produces only 80 × 25 text in a 9 × 14 character cell — but the larger cell yields a 720 × 350 pixel image that is noticeably crisper for office work. The card also carries the IBM PC's '''parallel printer port''' on its back-panel DB-25 connector, an idiosyncratic combination that means removing the MDA also removes the printer port. | The '''IBM Monochrome Display Adapter''' ('''MDA''') is the original 8-bit ISA monochrome text adapter IBM released alongside the [[IBM PC (5150)]] in 1981. Unlike the [[IBM Color Graphics Adapter|CGA]], the MDA has '''no graphics modes''' — it produces only 80 × 25 text in a 9 × 14 character cell — but the larger cell yields a 720 × 350-pixel image that is noticeably crisper for office work. The card also carries the IBM PC's '''parallel printer port''' on its back-panel DB-25 connector, an idiosyncratic combination that means removing the MDA also removes the printer port. | ||
== Hardware == | == Hardware == | ||
* ''' | * '''Motorola MC6845 CRTC''' — same timing chip as CGA, programmed for 18.432 kHz horizontal / 50 Hz vertical. | ||
* '''4 KB video RAM''' | * '''4 KB video RAM.''' | ||
* ''' | * '''Character ROM''' carrying the IBM MDA font in a 9 × 14 cell. | ||
* '''TTL output''' on DB-9 (drives the [[IBM 5151]]). | * '''TTL output''' on DB-9 (drives the [[IBM 5151]]). | ||
* '''Centronics parallel port''' on DB-25 — LPT1 by default. | * '''Centronics parallel port''' on DB-25 — LPT1 by default. | ||
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== Common Faults == | == Common Faults == | ||
* '''No video, beep code 1 long + 2 short''' — the MDA card | * '''No video, beep code 1 long + 2 short''' — reseat the MDA card first. | ||
* '''Garbled text''' — bad character ROM. Replace with a known-good donor. | * '''Garbled text''' — bad character ROM. Replace with a known-good donor. | ||
* '''Missing or duplicated columns''' — bad VRAM chip | * '''Missing or duplicated columns''' — bad VRAM chip. | ||
* '''Smoke from a tantalum''' — replace the failed | * '''Smoke from a tantalum''' — replace the failed tantalum. | ||
* '''Printer port dead but video fine''' — the | * '''Printer port dead but video fine''' — the 74-series latch or buffer on the parallel side has failed. | ||
== Hercules Compatibility == | == Hercules Compatibility == | ||
The Hercules Graphics Card from Hercules Computer Technology (1982) added 720 × 348 graphics on top of MDA's text mode | The Hercules Graphics Card from Hercules Computer Technology (1982) added 720 × 348 graphics on top of MDA's text mode. A genuine IBM MDA does '''not''' have these graphics modes — it is text-only. | ||
== References == | |||
* [https://en.wikipedia.org/wiki/IBM_Monochrome_Display_Adapter IBM Monochrome Display Adapter — Wikipedia]. | |||
* [https://www.seasip.info/VintagePC/mda.html Monochrome Display Adapter Notes], Seasip.info. | |||
== Related Pages == | == Related Pages == | ||
* [[IBM PC (5150)]] | * [[IBM PC (5150)]] | ||
* [[IBM 5151]] | * [[IBM 5151]] | ||
* [[IBM Color Graphics Adapter]] | * [[IBM Color Graphics Adapter]] | ||
* [[IBM PC (5150) Capacitor Replacement Guide]] | * [[IBM PC (5150) Capacitor Replacement Guide]] | ||
[[Category:IBM]] | [[Category:IBM]] | ||
Latest revision as of 10:25, 21 May 2026
| IBM Monochrome Display Adapter | |
|---|---|
 |
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| IBM PC Original Monochrome Display and Parallel Printer Adapter (MDA) | |
| Manufacturer | IBM |
| Type | 8-bit ISA video display adapter (text only) with integrated parallel printer port |
| Release date | 1981 (with the original IBM PC) |
| Interface | 8-bit ISA |
| Compatible | IBM PC (5150), IBM PC XT (5160), IBM PC AT (5170), PC-compatible clones |
| Connectivity | DB-9 TTL monochrome (drives the IBM 5151); DB-25 Centronics parallel (LPT1) |
The IBM Monochrome Display Adapter (MDA) is the original 8-bit ISA monochrome text adapter IBM released alongside the IBM PC (5150) in 1981. Unlike the CGA, the MDA has no graphics modes — it produces only 80 × 25 text in a 9 × 14 character cell — but the larger cell yields a 720 × 350-pixel image that is noticeably crisper for office work. The card also carries the IBM PC's parallel printer port on its back-panel DB-25 connector, an idiosyncratic combination that means removing the MDA also removes the printer port.
Hardware
[edit | edit source]- Motorola MC6845 CRTC — same timing chip as CGA, programmed for 18.432 kHz horizontal / 50 Hz vertical.
- 4 KB video RAM.
- Character ROM carrying the IBM MDA font in a 9 × 14 cell.
- TTL output on DB-9 (drives the IBM 5151).
- Centronics parallel port on DB-25 — LPT1 by default.
Video Mode
[edit | edit source]- Mode 7 — 80 × 25 text, monochrome.
- Per-character attribute byte selects: normal, bright, underline, reverse video, blink, invisible.
- No graphics mode.
Common Faults
[edit | edit source]- No video, beep code 1 long + 2 short — reseat the MDA card first.
- Garbled text — bad character ROM. Replace with a known-good donor.
- Missing or duplicated columns — bad VRAM chip.
- Smoke from a tantalum — replace the failed tantalum.
- Printer port dead but video fine — the 74-series latch or buffer on the parallel side has failed.
Hercules Compatibility
[edit | edit source]The Hercules Graphics Card from Hercules Computer Technology (1982) added 720 × 348 graphics on top of MDA's text mode. A genuine IBM MDA does not have these graphics modes — it is text-only.