[ddingus]

They also help on composite displays, still a significant consideration at the time the PC was created.

PAL didn't suffer too much from this, but NTSC did. Single pixel verticals light up in a rainbow of color. This is actually how the monochrome Apple 2 did it's color graphics!

White on blue is a secondary helper here. On sharp displays, the human eye sees the white text at full detail. Humans have only a fraction of blue receptors, compared to red and green. This means screen noise gets lost in a sea of blue.

On composite displays, that same sea of blue tends to was artifacts away. SGI IRIX offered it's Xterm with a great font, white on blue and it was very easy on the eyes.

I've used that combo for terminals ever since.

[rbanffy]

I think the only PC ever to ship with composite video output was the PC Jr. (edit: sadly, no, it wasn't)

I became fond of the white on blue scheme with the MSX machines, but kind of abandoned it when I moved to PCs.

[bitwize]

Not only did the CGA have composite out, but by playing with the signal timings it was possible for a CGA to output more colors than the four nasty "CGA palette" colors it's known for (no matter which palette you use, shit's nasty) to a composite monitor.

The demoscene prod "8088MPH" demonstrates this to spectacular effect.

[ddingus]

It was also very simple to just use the 640x480 graphics mode on a composite display. US NTSC color cycles 160 times in that display area, which yields 4 pixels per cycle.

That's a 16 color, any color any pixel display 160x200.

Some PC games offered this option. It should have been in the CGA spec. For memory reasons, 1 and 2 bits per pixel were common. However, the same amount of RAM offers the full color set at a reasonable, if modest, resolution. (For the period)

16 colors on a 160x200 display was considered "nice" at that time, and having it be official would have improved early PC gaming considerably.

[bitwize]

The drawback to this mode is it looks like ass on anything but a composite display -- which not a lot of people actually hooked up their CGAs to.

There was also a hack to set the display to text mode and reprogram the character height to fit 100 characters vertically on the screen, then use chopped-off block graphics characters to yield, in effect, a 160x100, 16-color, any color any monitor (composite or RGB) pseudo-graphics mode that compared favorably to, say, the 128x48 mono pseudo-graphics mode of the TRS-80. More PC games made use of this mode; one of the more notable recent ones is Paku Paku, a (remarkably good) Pac-Man clone.

[ddingus]

Yes, all tradeoffs. Of course, it was not too difficult to have multiple sets of art.

I like 160x100 presentations and thought they were a good use of the CGA personally. A lot of game can be done at that resolution.

Really, the thing for IBM to have done was 16 color graphics of some kind. 160x200 was the obvious choice in that it would have worked with their memory scan scheme.

[rbanffy]

> The demoscene prod "8088MPH" demonstrates this to spectacular effect.

I thought those were on an RGB screen. All the more impressed by the brilliance of those guys.

[ddingus]

Most PC CGA cards offered composite output. One could use a TV or higher resolution composite monitor and skip the expensive CGA one. I did this, as did a number of others I knew at the time.

[mschaef]

Yeah... the original PC could be scaled way down in terms of hardware. It had a cassette interface and ROM BASIC, so it didn't need floppy disks, the CGA could connect to a TV via an RF modulator, and it was available with as little as 16K of RAM. In other words - home computer level specs. That said, where it differentiated itself was its upgradability and software selection, so there wasn't much point to the most basic PC configurations.

To show the other end of the original PC spectrum, my family's first PC was a Compaq portable (a clone of an IBM PC), bought in the late 80's. That machine had 2 5.25" 360K floppy disk drives, 20MB Hard Disk, an 8087 FPU, 1200 baud modem, a mouse, and a higher-than-CGA resolution display for text. It was really a nice machine, and when I last checked a few years ago, it still runs.

[rbanffy]

I guess that having a nice separate character generator ROM for use with their TTL monitore (both for the CGA and the MDA) wound increase the cost. Damn bean counters.

I remember the frustration that my Apple II+ with Videx card (plugged to a monochrome monitor through composite) had nicer looking text than the IBM (mono CGA on RGBi) next to it. Even more infuriating, it was also better than the much better specced Apple IIe that sat to its other side (and used the stock font for 80-column text). And yes, even under PAL-M (PAL with NTSC timings), 80-column text on a color composite screen was awful. My II had a switch installed to turn off color signal generation, making the text much more readable.

[mschaef]

Yeah... IBM CGA text wasn't that good even in the best of circumstances. The 640x200 resolution and 8x8 character cells were really inadequate.

Part of the reason for this is that IBM split the market into CGA for graphics and MDA for better text (9x14 character cell). Because the MDA adapter didn't display graphics, IBM made it possible to run both a CGA and a MDA in the same machine. Software like Lotus 1-2-3 could put the spreadsheet on the MDA and the graphics on the CGA. Dual monitors in the mid-80's.

Prior to the development of the EGA and VGA, there were a few interesting competitive responses to IBM's CGA/MDA split. The first was the Hercules card. This would let customers that had bought IBM's MDA (and it's matching monitor) get access to graphics. It wasn't compatible with CGA graphics, but it was higher resolution and wound up being fairly widely supported where it mattered. Compaq also had a solution to the problem... they shipped adapter/monitor pairs that could display MDA-quality text in the text modes and would scale down to 640x200 to display graphics.

What ultimately wound up happening is pretty much what you'd expect. As graphics resolutions got better with EGA and VGA, the quality of text on color displays got to the point where the MDA didn't represent an improvement. That said, there was always the ability to run an MDA (or clone) in parallel with a EGA, VGA, etc... that configuration was useful to programmers because it let you put debug information on one display while the main display ran the software you were developing.

[rbanffy]

> Dual monitors in the mid-80's.

I had that on my II+. Motherboard would drive the modified 16" TV (40 column, graphics) and a Videx Videoterm-like card would drive the monochrome monitor with beautiful (for the time) text.

I remember that in the late 80's I started seeing MDA/CGA hybrids that would drive MDA monitors with CGA-compatible text modes with MDA-like fonts and PWM grays. By then I was getting used and their ugliness no longer offended me.

[ddingus]

Yes. I had similar experiences. That Videx card really shined.

At NTSC timings, 80 column text is basically color information. It's just terrible.

Interestingly, sets from about the 80's onward can display 80 column text nicely, given a good DAC driven signal. The signals from back then were square, or coarse, if not square. This makes NTSC light right up. I've been toying with a micro and a DAC and a full interlace, color phase shifting NTSC signal performs well on older analog sets. If the timing is right for the digital ones, they do well too, but it's all about hitting that 13.5Mhz sample window common to most digital sets today.

Back then, just having a full interlaced signal would have helped considerably with text, though at the expense of tearing. Low ambient light and moderate contrast on the display would have largely mitigated this.

As we got Y-C capable displays, one could just use a resistor and send the composite signal into both inputs. This actually did very seriously improve text.

[rbanffy]

> As we got Y-C capable displays, one could just use a resistor and send the composite signal into both inputs. This actually did very seriously improve text.

This is something I should try with my 8-bit machines.

[ddingus]

It works pretty well. Put a pot on the C line, and adjust it for the best overall look.