While NTSC allows 320 pixels, typical analog TVs overscanned a lot and you'd miss the right and left column or 2 of text.
The Apple always fit. Atari machines often didn't.
On my personal "monitor", I scored a finer dot pitch CRT and did a lot of work to put the entire frame on screen.
Atari did allow wide screen DMA which used up nearly the entire active display area.
I would run a 384x224 display on it sometimes.
And after a full alignment, better CRT, one could read 80 columns on the set and watch color programs look very good.
... a lot of the picture quality impact the pro grade CRT TV displays had was due to finer pitch CRT's.
The circuits matter too. Don't get me wrong.
Even without a spiffy fine pitch CRT, a well calibrated 80's era TV (some 70's era ones too), worked well as a monitor.
I had worked at a TV repair shop as a younger kid. The Atari machine I had was just good enough to generate respectable alignment and calibration signals. If you were willing to put in a good day, many sets could perform far better than they were just sitting there on, showing slowly degrading TV programs.
But, they tended to age and degrade a lot more quickly than we are used to today. I did my special one three times over the course of 5 years or so to keep it at peak.
That's another difference in the pro grade gear. It stays on point for ages.
With Apple setups, one could deliberately calibrate to maximize the essentially monochrome screen, and expand it to take up a larger area to get a little bit more benefit from the often coarse shadow mask on color sets.
Many people would just run both. Monochrome for text, some color TV for graphics.
A workaround for color sets was to run saturation a bit low and make sure the color killer circuit was hair trigger so it worked when the Apple requested no color.
Moderate contrast, bringing up the screen levels while at the same time lowering the drivers would sharpen things up considerably. End result was a decent resolution and that "don't use it in a brightly lit room" tradeoff.
Bonus points for tapping into composite, avoiding RF. Where I lived a lot of people had UHF modulator on their Apple computers. These worked on something like channel 34 instead of the more interference prone channel 2, 3 or 4.
The real fun began when VCR's got the scene. Hit record, set for SLP recording and you got an up to 8 hour record of what you did.
Or, run the VCR faster and get a higher quality record for show and tell or debugging.
If you crave a CRT today, obviously the pro grade displays on their way out are great. You will likely be impressed when watching something off DVD, or Bluray. Standard definition was much better than most of us saw due to the tradeoffs made in mass market displays.
But, those are harder amd harder to get.
The next best thing is a newer CRT. Clean and recap that if needed and then go through the alignment and calibration using one of the many DVD images available for that purpose.
Many of those have great filters that can do a lot for Apple 2 like signals.
Then enjoy the artifact art in all its glory!
http://www.appleoldies.ca/bmp2dhr/disclaimer/
The images on this page use the better "Double High Res" artifact color possible on the Apple //e
There are some examples of Apple 2, the original graphics being discussed here, on that page.
Many artists used patterns to exploit secondary artifact effects (best seen on an NTSC TV with color saturation turned up a bit), and our own color perception to produce images that appear more colorful than the basic 6 color design one would expect to deliver.
This pixel art can be seen all throughout the 8 bit era running from the late 70's to mid to maybe late 90's.
https://images.app.goo.gl/1wzZhp76tsC3hC6G6
In that one, only one color attribute set was used. Black, white, orange and blue. The secondary artifacts shows nicely here.
A single orange pixel by itself on black delivers a little bit different overall image color when nestled in all white pixels.
Dithering coupled with these subtle effects could really change the overall viewer perception!
In addition, due to how the NTSC color worked, intensity and color got coupled together, giving pixels a sort of texture and subtle position difference when viewed on a color display. On the Apple, this can be seen as a smudge of color around the pixel. You can see this in the lower resolution graphics where the pixels literally don't quite line up.
Many more and better can be seen on the Total Replay image being developed right now.
Emulators have modeled what a real display would do very well. You get a whole lot of the experience that way.
I don't think overscan would be an issue. The TMS9918 is also (the equivalent of) 320 pixels wide, and it was used in many different home computers and game consoles intended to connect to the family TV. There's no overscan issue, unless it's connected to an Apple II monitor.
When the TMS9918 is connected to an Apple II monitor there is a huge overscan issue, since the monitor is tuned for the narrower Apple II screen. It looks like this: https://imgur.com/rGcRpw0
That's what got me thinking about this issue is the first place.
If they'd shipped with 320-wide video, a lot of people wouldn't have seen the prompt on the left hand side.
That's the heart of the question. Did Woz think that 320 pixels would not fit, or did he cut the width down for another reason, like more color.
If you look at the video generation circuit on an Apple ][ it's all done in real-time in TTL, alongside the DRAM refresh activity. And it's all crammed into the normally unused tock of the 6502, making this work with virtually zero overhead on the CPU. That's the reason why the memory mapping of the screen isn't linear to the physical display. The software tradeoff was cheaper than the hardware one.
http://twimgs.com/informationweek/byte/archive/Apple-II-Desc...
Overall, given memory expansion, the goofy screen didn't end up being too big of a deal. Most programmers made Y axis lookup tables and called it a day. The fact that the artifact color mapping repeated every word, two bytes, did have an impact in that it was generally faster to maintain two pre-shifted copies of software sprites though.
You'd think that the 9918 would be a bottle neck between the CPU and the VRAM, but the Apple II can write to the 9918 VRAM as fast as its own internal RAM. Faster, actually, since the destination address auto-increments. That was a surprise.
Hmmm, is the bitmap linear by line, or C64 style?
Auto increment + C64 style would rock pretty hard. It's still good per line.
Both have their merits.
A single screen is divided into 3 separate tile maps, each 256 bytes long.
It also supports 32 spirtes but only 4 sprites per scanline, which is its biggest limitation.
The Sega Master System used an upgraded version of the 9918, adding 64 colors, smooth scrolling, and 8 sprites per scanline, all within the same 16 kB of VRAM.
Yeah, auto-increment can rock! Blasting characters to the memory would be fast, and only require a precise index for the source data. Perfect for the 6502. Other index can be done every so often, depending on what is being drawn.
In the Apple 1, only 7 bits were output. Expanding that circuit to do graphics would take a byte and still output just 7 bits, simple.
People are pretty sure the Apple 1 video circuit was just expanded to do graphics, which is why it's 7, and that left the high bit for a color shift.
Here's an example Atari BASIC program that uses POKE statements to change and then restore the default margins.
Interesting! I never noted that before.
I don't know whether this story is true, but it's what we were told.
That's a funny little piece of computer history.
This image (white text on a blue background) shows how the 9918's native pixels line up with the NTSC color burst frequency: https://imgur.com/rGcRpw0
The phase shift makes a big difference.
Having 6 colors and the artifact art variations was enough to do pretty much anything, not always well.
Had it been 4 color, it all would have been far more limited.
Frankly, the screen being good enough may be part of why graphics adapters never became common.
I always thought they should have.
Once accelerators took the 6502/816 to 4Mhz plus, a graphics adapter, perhaps combined with a faster CPU would have made a ton of sense.
The power of the default was stronger due to that 6 color capability, IMHO.
Compare 4 color CGA and it is notable.
That said, CGA over NTSC was Apple like with 16 colors, no attribute clashing. That is what an expansion card for the Apple 8 bitters should have done.