Hacker News Reader

Comment by Dwedit | Hacker News Reader

The game is not running from RAM, it is running from Flash ROM. This means that code and static data can be placed on ROM rather than in RAM.

This is comparable to the GBA, which has 384KB of total RAM, and a ROM cartridge slot for storing the game code and data. But the GBA is only 16MHz, the EFR32MG24 system used for this project is overclocked to 136.5MHz.

View on HN

The article says that even if you put all the static data to flash, you still have to fit about 1.5 MB of non static data, if you don't optimize it. Beside that, all graphics is loaded from the relatively slow external SPI flash, which tops at 17 MB/s with overclock. Yes, the GBA is much slower, but the access to cartridge data is faster than 17 MB/s (and also the random-read speed is in the 100 ns range, not 1-2 us range).

>This is comparable to the GBA, which has 384KB of total RAM

I assume you are thinking of the 32KiB of on-chip work RAM plus 256KiB of on-board work RAM plus 96KiB of video RAM. But pedantically there is also a 1KiB region of palette RAM and 1KiB of "object attribute memory", separate from the VRAM, making 386KiB total. (Not counting the I/O control registers, which one ordinarily wouldn't think of as "memory" but get a dedicated region of that address space.)

Aside from the ROM on a cartridge - up to 32MiB - there is 16KiB of BIOS ROM, and the system can address 64KiB of EEPROM for game save data.

https://problemkaputt.de/gbatek.htm#gbamemorymap

I really don't count Palette and OAM as extra memory, despite me having used unused palette memory as a place to store sound sample data.

Reply on news.ycombinator.com