Problem Statement

In systems programing it is sometimes required to place language objects at specific memory locations, like I/O registers, hardware interrupt vectors etc.

Show how language objects can be allocated at a specific machine addresses. Since most OSes prohibit access to the physical memory if it is not mapped by the application, as an example, rather than a physical address, take the address of some existing object (using suitable address operations if necessary).

For example:

Let's start with the solution:

var portaddr = 0x80
var v = peek (portaddr, 1)   // 1 byte
v |= 0x40
poke (portaddr, v, 1) // 1 byte back again

var addr = malloc (16)
poke (addr, 1234, 4)
poke (addr+4, 0, 2)
poke (addr+6, 12, 2)