is also available where only 5 bits of data per pixel are used. The sixth bit is always zero, so only the blue color component can be modified. This mode is not as flexible as HAM6 and not widely used. Sliced HAM mode (SHAM) The Original Amiga Chipset included a support chip known as the "Copper" that handles interrupts and other timing and housekeeping duties independently of the CPU and the video system. Using the Copper, it is possible to modify chipset registers or interrupt the CPU at any display coordinate synchronously to the video output. This allows programmers to use Copperlist or CPU code for video effects with very low overhead. Using this technique, programmers developed the Sliced HAM or SHAM mode, also known as dynamic HAM. SHAM changes some or all color registers on selected scan lines to change the palette during display. This meant that every scan line can have its own set of 16 base colors. This removes some constraints caused by the limited palette, which can then be chosen per-line instead of per-image. The only downsides to this approach are that the Copperlist uses extra clock cycles of the chip RAM for the register changes, that the image is not bitmap-only, and the added complexity of setting up the SHAM mode. This technique is not limited to HAM, and was widely used with the machine's more conventional graphics modes as well. Dynamic HiRes uses a similar palette changing technique to produce 16 colors per line in the high resolution modes, whereas HAM is limited to low resolution but allows both 16 indexed colors as well as modifications of them. The SHAM idea was deprecated when HAM8 was introduced with the AGA chipset, since even an unsliced HAM8 image has far more color resolution than a sliced HAM6 image. However, SHAM remains the best available HAM mode on those Amigas with the original or ECS chipsets. Advanced Graphics Architecture HAM mode (HAM8) With the release of the Advanced Graphics Architecture (AGA) in 1992, the original HAM mode was renamed "HAM6", and a new "HAM8" mode was introduced (the numbered suffix represents the bitplanes used by the respective HAM mode). With AGA, instead of 4 bits per color component, the Amiga now had up to 8 bits per color component, resulting in 16,777,216 possible colors (24-bit color space). HAM8 operates in the same way as HAM6, using