Cycle stealing

Cycle stealing is a method of accessing RAM without interfering with the CPU. It is similar to DMA for allowing I/O controllers to read or write RAM without CPU intervention. Clever exploitation of specific CPU or bus timings could permit the CPU to run at full speed without any delay if external devices may sneak in one RAM access to memory not actively participating in the CPU's current activity and complete the operations before any possible CPU conflict. Such systems are nearly dual-port RAM without the expense of high speed RAM. Most systems halt the CPU during the steal, essentially making it DMA by another name.