Masami Ishikawa over hoe hij de hardware voor de SEGA MegaDrive ontwierp

RDJ134 5 februari 2015 om 16:56 uur

De SEGA MegaDrive was toen deze uitkwam een game changer en kwam lijnrecht tegenover Nintendo te staan die snel grond begon te verliezen met hun Super Nintendo. De reden hier voor was dat de SNES werd gezien als een kinderconsole en SEGA zich meer richte op tieners en jong volwassenen. Nu decennia later weten we dat beiden systemen onwijs goede titels heeft voortgebracht en er eigenlijk geen winnaar was in de 16-Bit oorlog. De man achter de hardware van de SEGA MegaDrive was Masami Ishikawa en een interview met hem over zijn werk kan je hier lezen.


What were your priorities with the Mega Drive architecture?

MI: We wanted the Mega Drive to have the basic performance of the preceding system boards - the System I, System II and System 16 - and we wanted to preserve compatibility with the Mark III. In fact, even SG-1000 II titles were playable on the Mega Drive. The top priority was the Mark III compatibility - in order to retain gamers who owned older systems - while at the same time maximising the graphic performance. The crux was how to optimise the efficiency of the memory access cycle with the graphic memory. We also separated the CPU into a graphic component and sound component to lessen the stress on the game program. The Mark III compatibility meant that it also had a Zilog Z80 CPU. When the Mega Drive was in Mark III mode, it was mainly running on the Z80, but when it was in Mega Drive mode, the Z80 was used only for sound.

What were the major strengths of the hardware in terms of graphics?

MI: I think its strength was in having multiple displays. We were able to have two scrolling windows - with both vertical and horizontal line scrolling - and the sprite size could be changed to fill the whole display. It could also display the background screen behind the scrolling window and could change the color of each line. The number of available colors was limited compared to comparable arcade systems, but it could create shadows that matched each character's shape and was also capable of semi-transparency. The biggest hurdle was the size of the chip. We wanted to include enlarging and minimizing capabilities as well as sprite-spinning functionality, but the circuit design was becoming too large to fit on one chip, which would have lowered the production yield rate and hiked up costs, so we had to remove it from the spec. The number of available colors was also limited by the size of the circuit structure.

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