Was just doing the maths... Just the arrays in the incomplete sketch are over 700 bytes.
sounds like that's the issue. I thought that when it compiled the sketch it would take the binary sketch size limit into consideration.
Program memory is separate from RAM, which is used for variables, stack, etc. The "Binary sketch size" reported by the IDE is the program size, not the amount of RAM used. The amount of RAM used cannot be determined at compile time, and indeed is not a single number, as memory can be allocated and released as the program runs. The program is stored in flash memory which is normally read-only during execution. RAM on the other hand, is read/write.
How do you calculate how many bytes a sketch will use? Do you know if there's a reference chart that states the size limitations of the different ATTINY's or ATmega's?
The datasheet is the reference, for example, http://www.atmel.com/Images/doc8271.pdf
, memory sizes are listed on the first page.