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Coloured bar curiosity

Posted: Wed Jan 18, 2017 9:31 am
by catmando
Why do we often see multi-coloured bars on games that are packed when loading?

Used to see this all the time on speccy and c64 games back in the day too.

Re: Coloured bar curiosity

Posted: Wed Jan 18, 2017 9:55 am
by aktiv8
The colours are just there for my understanding to show that something is going on - a simple change in the register that invoked can change the colours etc. Quite a few packers and groups didn't have the lines, and it could also be turned off

In terms of the spectrum, in some part it was to show data was going in to the system - again showing something is happening - but in the Speccy case the cyan and red then yellow and blue stripes were to so with the lead in and data streams too from memory

Re: Coloured bar curiosity

Posted: Wed Jan 18, 2017 11:57 am
by AtariZoll
I guess that main reason was the slowness. So, they added some simple indicator that computer is not frozen or crashed. Loading from tape in case of Spectrum could take about 5 minutes. Some depackers on Atari ST needed about 1 minute for couple hundreds of KB.

Re: Coloured bar curiosity

Posted: Wed Jan 18, 2017 11:37 pm
by catmando
Why not a simple loading bar? Or hadn't they thought of that back then?

Re: Coloured bar curiosity

Posted: Thu Jan 19, 2017 8:17 am
by swapd0
Do you mean a progress bar? It takes a lot less CPU time to change the border colour, also you don't smash the screen to draw the progress/loading bar.

Re: Coloured bar curiosity

Posted: Thu Jan 19, 2017 8:38 am
by AtariZoll
Progress bar would be indeed much better. And harder to code. But not much. I remember doing very simple and just 2 hor. lines high one for my movie playback. So, it did not hurt screen content much. About 40 lines of ASM code, very low CPU time usage.
There were diverse progress bars for loaders - by Spectrum and Atari ST too. But I don't remember seeing progress bar used by depackers.

Re: Coloured bar curiosity

Posted: Thu Jan 19, 2017 9:17 am
by joska
AtariZoll wrote:I guess that main reason was the slowness. So, they added some simple indicator that computer is not frozen or crashed. Loading from tape in case of Spectrum could take about 5 minutes.


In addition to show that something was actually happening, the loading bars on the Spectrum had the additional purpose of indicating whether it was loading data or metadata.