CGA/MDA Video Adapter Lab - Engineering Application
Restoration and validation workflow for monochrome and color text-era adapters, including monitor timing and character ROM behavior.
- Adapter Modes
- MDA, Hercules-compatible, CGA text and graphics
- Output Paths
- TTL monochrome, composite, RGBI output checks
- Clock Profiles
- 14.31818MHz domain checks and divider validation
- ROM Handling
- Character ROM preservation and checksum workflow
- Display Validation
- Geometry, sync, and phosphor persistence tests
- Field Scope
- Pre-286 display stack bring-up and troubleshooting
Graphics and Display
The PC1640's standout feature was its integrated EGA-compatible graphics, acquired from Paradise Systems and built directly onto the motherboard. The ECD (Enhanced Colour Display) model could display all EGA modes. Critically, the PC1640 allowed replacing the internal graphics adapter with an 8-bit ISA VGA expansion board, making it significantly more versatile than the PC1512. CGA and Hercules monochrome modes were also supported for backward compatibility.
XT-Emporium NT