Computing Misconceptions

[HEXdidnt]

Every so often, watching YouTube videos about retro computers and consoles, I learn something that appears to go against what I thought I knew at the time. Now, considering my technical knowledge of computers generally is pretty low, this should surprise no-one... For example, I had thought for many years that the SAM Coupé's palette of 128 colours was a result of bugs that effectively halved the number of R/G/B levels one could use to mix colours. In fact, it was actually a late change of one of the chips that allowed them to increase the number of colours by effectively adding a 'bright' option to its original palette of 64 colours.

But it's not always technical matters that lead to misconceptions.

For example, I often find retro YouTubers referring to the ZX Spectrum as having a 'dead flesh' keyboard... but I'd always though it was the description for the ZX81's keyboard, due to its weird leathery texture. The original Speccy was the 'rubber keyed' one, right? It certainly didn't feel like dead flesh to me, while the ZX81's did feel uncannily like a thin layer of jerky attached to the case. If the ZX81 isn't the one with the 'dead flesh' keyboard, what's the proper description for that horrific texture?

Anyone have a definitive answer to this question?

Anyone have any other, similar misconceptions from their youth?

 

[Retro]

I've probably had technical misconceptions, but I can't think of any at the moment. There's certainly things where I felt confused for a long time over how they worked though, which eventually got cleared up when the internet came along and I was able to Google them.

 

[Mort]

To be honest, after using the ZX81's keyboard, the Spectrum 48K was quite an improvement.

I think the ones with the snidey comments about it just had machines with nicer keyboards (CBM machines + BBCs)

 

[HEXdidnt]

Another misconception of mine: What constitutes 'a sprite' in videogames.

I'd always thought that 'a sprite' was an entire moving object of whatever size... but having recently read some articles and watched some YouTube videos about the way arcade machines and home consoles handled their sprites, I've had my mind blown.

For example, the average system uses either 8x8px or 16x16px sprites. Larger objects are literally just groups of these sprites linked together so that they appear to be a single, cohesive unit.

There was an excellent boxout on sprites in the Neo Geo article in issue 215 of Retro Gamer, which explained that it used 16x16 sprite 'tiles', and 'a sprite' on this machine is a vertical strip of up to 32 tiles (or 512px). Multiple of these vertical strips of tiles can then be linked horizontally, with the leftmost sprite being the reference point for the others in each group.

It seems counterintuitive to me, but I guess moving a larger number of smaller sprites was less CPU-intensive than a smaller number of larger sprites. I gather some sprite limits can be circumvented by using what's called 'Blitter Objects' (aka BObs), which are handled by a different bit of hardware and had fewer practical limits, particularly in terms of quantity in motion at any time.

Something I found stunning about the Neo Geo was its 'auto-animating sprite' capabilities, which meant that a part of its video hardware was able to animate 4- or 8-frame loops (generally acting as background elements) without involving the CPU at all. The only drawback appears to have been that every one of these loops would run at the same speed.

 

[chrisns]

@HEXdidnt , I think you need to declare your experiences and expertise with "dead flesh" before I fully comment! eg: if you spent time curating Egyptian Mummies for a museum, I could see the parallel with ZX81 feeling leathery (but also clinically dead)

And totally agree on the Sprite comment, especially based on very brief conversation on the topic yesterday.... I suspect the definitions have tweaks between both particular systems and graphical generations

 

[HEXdidnt]

@chrisns does a dead pet count? Other than that, my experience would, admittedly, be limited to the occasional (and wholly misguided) consumption of beef jerky.

On the subject of sprites, I guess the majority of my confusions does come from my dabblings in SAM BASIC, where a sprite can be made out of anything on screen, with a limit of 8K per graphic stored as a string. That said, I can look back at, say Renegade on the Spectrum, in which it's clearly visible that each character is made up of two 24x24px sprites - one for the upper body, one for the legs - at least as far as the walking animation goes.