2024-01-23

New Screenshot Color Features

View CGA and Amstrad CPC Screenshots With Different Monitor Types

Another code update has been pushed live for PixelatedArcade, and this time around the main new feature adds the ability to view some screenshots with colors simulated for different monitor types. When supported, you'll see a drop-down menu below screenshots after clicking on them which allows you to select your preferred monitor. A while back I had written about tales of CGA colors, and this update finally delivers the feature to view different CGA color possibilities. Additionally, you can also view Amstrad CPC screenshots in both color and monochrome. Previously this feature was available for Apple II and Hercules Monochrome screenshots, so I'm delighted to introduce this expansion!

But, why would you want to view different options? As I've alluded to before, not all of us could afford the latest and greatest hardware in the 1980's. Computers were quite expensive, and having to cut back on some options was common. Being able to view some of the variations that existed is nice both for people who wish to see games as they remember them on their particular computer as well as for those who didn't realize so many differences existed to have an opportunity to see their favorite games in a different light. The exact way graphics looked was far less homogeneous than might be expected but knowledge and documentation of the options has been improving greatly and emulators are offering both more accurate representations and emulation of more varied hardware options. Similarly, offering the ability to see some variations while simply browsing without having to install an emulator is also important. So, let's take a look at what's new; here's the display options added with a quick description.

Color/Graphics Adapter (CGA) Monitor Types

CGA cards could be connected to a composite monitor/T.V., or to a direct-drive monitor. Upon release of the IBM PC in 1981, IBM didn't offer their own direct-drive monitors, but third party ones were available. IBM wouldn't offer their own direct-drive color monitor until the release of the IBM 5153 in 1983; Due to this delay and the CGA specs not clearly defining how colors should appear there are a number of possibilities for exactly how the graphics would have looked back in the day. Here's the choices added to PixelatedArcade's CGA screenshots:

  • CGA's 16 colors with RGBi (Canonical) monitor RGBi (Canonical):
    The 16 CGA colors as you are most likely used to seeing them as it reflects what most later color CGA monitors and emulators display as well as what you'll get with EGA, VGA, and other graphics standards that are backwards compatible with CGA. Color 6 is brown here and the intensity bit is supported allowing all 16 colors to be displayed. On some monitors, notably those from Tandy, brown and red can even be difficult to tell apart.
  • CGA's 16 colors with RGBi (IBM 5153) monitor RGBi (IBM 5153):
    The 16 CGA colors are tweaked to closer resemble those seen on an IBM 5153 color display. Color 6 exhibits the most noticable difference; it is still brown, however it's slightly lighter and contrasts with red better. The 5153 is unusual in that the contrast knob only affects the low intensity colors; high intensity colors remain the same so actual results with this monitor may vary depending on how contrast is set.
  • CGA's 16 colors with RGBi (Yellow) monitor RGBi (Yellow):
    Simulates an RGBi monitor which does not have the circuitry to turn color 6 to brown appearing instead as dark yellow. Other colors in this palette are the same as the canonical version. Monitors of this type weren't particularly common and I believe were mostly released early in the PC's life before IBM's 5153 became available.
  • CGA's 16 colors with RGB monitor; only 8 colors are possible RGB:
    Simulates a monitor which does not support the intensity bit. Only 8 colors are possible with the low and high intensity colors being identical. Color 6 appears as yellow and not brown as the circuitry to adjust the color wasn't present. Like above, this type of monitor wasn't common later in the PC's life.
  • CGA's 16 colors with monochrome monitor Monochrome:
    Simulates a CGA card connected to a monochrome display. There are three options here to simulate displays using green, amber, or white phosphors. While IBM's CGA cards could only be connected to a monochrome monitor via the composite output, clones of IBM's graphics cards were available from third party manufacturers which offered more extensive options. Results may vary somewhat depending on the specifics of the actual monochrome monitor used and whether it was composite or TTL along with what model of CGA card was installed.

Depending on the palette and specific colors a game uses, there may not be much (if any) difference) noticable between some options while with other games the difference is quite obvious. There are also still some options not yet supported that I hope to add soon; the IBM PC Portable Computer (commonly known as the one that's more luggable than portable) sported an LCD monochrome display with a reddish/amber color. The IBM PC Convertible also featured an LCD display, but instead with an unusually wide aspect ratio and a blueish white color. There are likely others I've missed (especially from third party manufacturers), and there were also some differences in the composite output with early and late model CGA cards which could affect both the monochrome and color displays. Over time I hope to include these possibilities that are still missing as well as make sure all options offered are as accurate as reasonably possible. Also, if you're interested in a more detailed analysis on the IBM 5153's colors, check out The IBM 5153's True CGA Palette and Color Output on the Int10h blog.

Amstrad CPC Monitor Types

The Amstrad CPC was available with either a color monitor (CTM640/CTM644) or a green monochrome monitor (GT64/GT65). Later models in the line also had a white monochrome monitor option.

  • Amstrad CPC color monitor reference Color Monitor:
    The Amstrad CTM640/CTM644 could display 27 colors. The only difference between the two models is the availability of a 12v power supply for an optional disk drive.
  • Amstrad CPC monochrome monitor reference Monochrome Monitor:
    The Amstrad GT64/GT65 monochrome monitors used a green phosphor and could display 27 shades. Similar to the color options, the difference between the two was the power supply for a disk drive.

Currently the monitor simulation is limited to the original Amstrad CPC models; later models such as the Amstrad Plus and GX4000 which supported more than 27 colors in the palette will not yet have the monitor selection, a limitation that I hope to correct at some point soon.

That's all of the updates for today, so take care and I hope you have a great 2024!