It's not difficult to write a memory allocator, but there are some assumptions there which don't always hold true. For instance SmartCards (e.g. SIMs) use a lan

It's not difficult to write a memory allocator, but there are some assumptions there which don't always hold true. For instance SmartCards (e.g. SIMs) use a language alleged to be Java, but without a garbage collector and with only one data type. Applications never terminate, so while you can allocate heap memory, you cannot free it and memory exhaustion is one way to brick the device. Since it is "Java" you don't have the low level control of C. Standard practice is to allocate some global variables once, and use them throughout the life of the device. Since another way to brick the device is by exhausting write cycles on the EEPROM on which these variables are stored, you are also allowed to allocate an array in the small amount of RAM. Ah, you might think - I can use that for an allocator! Nope. The array space is only allocated until the end of an event handler, and after that it holds undefined content.