Memory

What is Memory?

Memory is the thing that everything is stored in on the ti86 - programs, strings, variables, the 'operating system', temporary storage for calculations and even what is on the screen. There are two types of memory - RAM and ROM.

RAM

RAM is Random Access Memory. It is lost when you take all the battries out of your calcuator (including the 'backup' battery). It can be modified and contains anything you can delete from the [MEM] screen along with a few other things. It is not lost when the calculator is switched off as it is still getting power from the batteries - the calculator is not truly off.

ROM

ROM is Read Only Memory. It contains the 'operating system' and the program that interperets programs written using the built-in language. ROM can't be changed (without a screwdriver...).

Memory Locations

It says on the box for the ti86 that there is 128Kb of memory. This is not true. If you reset your calculator and then look at the [MEM] screen there appears to be less than 100Kb. Experienced assembly programmers will tell you that there is over 300Kb (I think that there's about 384Kb in total). But this will be explained later on.

What is important is what the memory is made up of. It is easiest to think of memory as sort of an array with 65536 storage locations (that's the number we'll start off with for now). Each of there storage locations contains an 8-bit value (0 to 255, or $0 to $ff, or %0 to %11111111).

Each memory location has an address. For ease of reading these are expressed in hexadecimal. The 'first' memory location has an address of $0 and the 'last' has an address of $ffff.