IBM 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.
| IBM 5151 Personal Computer Display | |
|---|---|
 |
|
| 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 |
Display Characteristics
edit- 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 CGA, because CGA runs at 15.75 kHz horizontal — well below what the 5151's flyback can lock to.
Input Connector
editA 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 MDA.
Common Faults
edit- 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
editThe 5151's CRT retains a lethal anode charge. Discharge before opening — see CRT Discharge Procedure.
References
edit- IBM 5151 — Wikipedia.
- IBM, IBM Monochrome Display (5151) service documentation.
Related Pages
edit- 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