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SNES: WRAM is DRAM, not SRAM #436

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SNES: WRAM is DRAM, not SRAM #436

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Expand Up @@ -120,12 +120,14 @@ For comparison, the 68000 employs a vector table to handle exceptions, ensuring

### (Lots of) more memory

It's fascinating to realise how much content the NES managed to display with only [2 KB of RAM](nes#memory). Well, the Super Nintendo now features **128 KB of SRAM** (still referred to as 'Work RAM' or WRAM) - a staggering 6400% increase in general-purpose memory compared to its predecessor.
It's fascinating to realise how much content the NES managed to display with only [2 KB of RAM](nes#memory). Well, the Super Nintendo now features **128 KB of RAM** (still referred to as 'Work RAM' or WRAM) - a staggering 6400% increase in general-purpose memory compared to its predecessor.

So, what can developers do with this? Anything they desire, really. WRAM is used to store variable data for the game. The more space available, the greater the amount of information that can be stored and processed (thus, reducing reliance on [cartridge hardware](nes#cartridgegame-data)).

However, as the following sections will demonstrate, the Super Nintendo is a fairly complex machine (albeit its 'simplistic' CPU). I tend to call this console a 'collection of mini-computers/subsystems'. Each subsystem may need data from the CPU, meaning programmers may reserve portions of WRAM to process that information - thus justifying the need for 128 KB of memory.

Furthermore, while the RAM in the NES was fast SRAM, Nintendo opted to use DRAM as technology for the Super Nintendo's WRAM. As it stands for *dynamic* RAM, this type of memory needs to be refreshed periodically. The 5A22 performs this automatically, but during this refresh operation, the CPU must be paused. This causes an overall CPU slowdown of roughly 3%.

## Graphics

After everything discussed so far, let me tell you that the graphical subsystem of this console is a true feat of engineering. Given its constrained CPU, one might assume the SNES could never cast a shadow on [its competitor](mega-drive-genesis), which boasts a '32-bit' Motorola 68000. Yet, Nintendo and Ricoh engineers devised clever tricks that exploit the behaviour of CRT displays, effectively expanding the console's capabilities without the need for expensive, state-of-the-art components.
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