Flicker fixer
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A flicker fixer or scan doubler is a piece of
CRT
computer monitor. Flicker fixers in essence create a progressive frame of video from two interlaced fields of video.
Flicker fixers
RAM while simultaneously outputting the line alternately with the corresponding neighboring lines from the field stored previously (weaving). Some more advanced flicker fixers integrated in add-on graphics cards use more sophisticated methods. Outputting the image at double scan rate essentially composes a progressive display with all lines from both fields at full vertical refresh rate. This promotes the horizontal frequency of the signal from 15.734 kHz to 31.47 kHz (in the NTSC case, numbers for PAL are slightly lower), which can be the used to drive a VGA
monitor from an output device.
Use with the Amiga
One computer capable of producing an interlaced image is the
gaming
, but since the original Amigas were unable to produce vertically high-resolution displays without flickering this was unsuitable for office-like usage where one might need to work with a clear high-resolution image for several hours. Flicker fixers were devised to remedy this.
The later iteration of the Amiga - the
AGA chipset could also output VGA display modes. Commodore offered the A2320 Display Enhancer Board for this purpose,[1] The board fit neatly in a video graphics adapter slot on the A2000 series computer. It supported the new video modes offered by the Enhanced Chip Set (ECS) and AmigaOS
2.0, including the Productivity Mode. Also, the earlier A2024 'Hedley' greyscale monitor featured an integrated flicker fixer, supporting up to 8 shades of grey.