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The Pickford BrothersJohn and Ste


Zub Sprites Amstrad

Archive entry by Ste Pickford on Sun, 26 Nov 2006
Subject: Zub

Ste Pickford

In light of the very limited RAM space we had to work in on 8-bit home computers, it's interesting to compare the Spectrum and Amstrad versions of the same game, as the machines were pretty similar in internal architecture. The Spectrum had 48K RAM, but the screen (256 * 192 pixels, 1 bit per pixel) took around 6K or so, and with other bits of system stuff reserved there was around 40K free for the game to use. The Amstrad had a whopping 64K RAM, but the screen was a fair bit larger, and had 4 colour graphics, so the screen took up something like 16K (320 * 200 pixels, 2 bits per pixel), and with system stuff reserved there was probably only about 44K free.

That's still slightly more than the Spectrum, right? Wrong! All the in-game graphics took twice the RAM because 2 bits were required for every pixel, rather than 1 bit on the Spectrum. By doubling the size of all graphics, in more or less the same amount of free RAM, the Amstrad version of a Spectrum game (where the Spectrum was the lead version, as it usually was) always required some drastic cuts to fit in RAM. The perception was that the machines were more or less the same, or that the Amstrad was slightly better, so we had to try and make the cuts as close to invisible as possible.

Here you can see that we cut out about 30% of the animation frames for the main character. This was a shame as Zub's animation was the main charm of the game.


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