Editing IBM 5151

{{Infobox computer peripheral
| name          = IBM 5151 Personal Computer Display
| image         = [[File:IBM 5151 5153 5154 monitors.jpg|260px]]
| caption       = IBM monitors from left to right: 5151 monochrome, 5153 colour CGA, 5154 EGA
| manufacturer  = IBM
| type          = TTL monochrome CRT monitor
| release_date  = 1981 (with the original IBM PC)
| interface     = TTL digital, 9-pin D-shell (paired with the [[IBM Monochrome Display Adapter]])
| compatible    = [[IBM PC (5150)]], [[IBM PC XT (5160)]], any MDA / Hercules-compatible system
| dimensions    = 12" CRT (~11.5" diagonal viewable area)
| model         = 5151
}}

The '''IBM 5151''' (the '''IBM Personal Computer Display''') is the 12-inch green-phosphor TTL monitor IBM shipped with the original [[IBM PC (5150)]] when it was paired with the [[IBM Monochrome Display Adapter]] (MDA). The 5151 displays 80×25 text only — it has no graphics capability — but produces a 720×350-pixel character image because the MDA generates a 9×14 dot character cell rather than the smaller cell used by the CGA.

== Display Characteristics ==

* '''Phosphor:''' P39 (long-persistence green); reduces flicker but smears on moving content.
* '''Resolution:''' 720 × 350 pixels, addressed as 80 × 25 characters in a 9 × 14 dot cell.
* '''Horizontal scan:''' 18.432 kHz.
* '''Vertical scan:''' 50 Hz.
* '''Brightness levels:''' three (off / normal / bright), encoded across the TTL video + intensity pair.
* '''Anti-glare:''' etched front glass.

The 5151 will '''not''' work with the [[IBM Color Graphics Adapter|CGA]], because CGA runs at 15.75 kHz horizontal — well below what the 5151's flyback can lock to.

== Input Connector ==

A 9-pin D-shell, TTL-level signals.

* '''Pins 1, 2:''' Ground
* '''Pin 7:''' Video
* '''Pin 8:''' Horizontal sync
* '''Pin 9:''' Vertical sync

The 5151 derives its three brightness levels from the combination of the Video and Intensity lines on the [[IBM Monochrome Display Adapter|MDA]].

== Common Faults ==

* '''Yoke or flyback whine''' — reflow flyback transformer joints.
* '''Dim or shrunken raster''' — service the analog board electrolytics.
* '''Flickering brightness''' — clean the DB-9 input contacts.
* '''No display, audible flyback''' — failed video amplifier transistor, or open filament on the CRT.

== CRT Safety ==

The 5151's CRT retains a lethal anode charge. Discharge before opening — see [[CRT Discharge Procedure]].

== References ==

* [https://en.wikipedia.org/wiki/IBM_5151 IBM 5151 — Wikipedia].
* IBM, ''[https://minuszerodegrees.net/oa/OA%20-%20IBM%20Monochrome%20Display%20(5151).pdf IBM Monochrome Display (5151)]'' service documentation.

== Related Pages ==

* [[IBM PC (5150)]] — the system the 5151 was sold with
* [[IBM Monochrome Display Adapter]] — the adapter card that drives the 5151
* [[IBM 5153]] — the colour equivalent
* [[CRT Discharge Procedure]]

[[Category:IBM]]