Amiga 500 - Technical Specifications

Technical Specifications

• OCS (1.2 & 1.3 models) or ECS (1.3 and 500+ 2.04 models) chipset. ECS revisions of the chipset made PAL/NTSC mode switchable in software.
  • Graphics can be of arbitrary dimensions, resolution and colour depth, even on the same screen.
  • Without using overscan, the graphics can be 320 or 640 pixels wide by 200/256 or 400/512 pixels tall.
  • Planar graphics are used, with up to 5 bitplanes (4 in hires); this allowed 2, 4, 8, 16 and 32 colour screens, from a palette of 4096 colours. Two special graphics modes were also included: Extra HalfBrite, which used a 6th bitplane as a mask that halved the brightness of any colour seen, and Hold And Modify (HAM), which allowed all 4096 colours on screen at once.
  • Rhett Anderson developed the so-called Sliced HAM or SHM mode, which was a standard 32-color mode, but used the Copper (part of the Agnus chip which could change hardware registers at given screen positions) to reprogram the color palette registers at each scanline. The advantage of SHM files was the ability to display all 4096 colors while eliminating the color blur of HAM compression.
  • Sound is 4 hardware-mixed channels of 8-bit sound at up to 28 kHz. The hardware channels had independent volumes (65 levels) and sampling rates, and mixed down to two fully left and fully right stereo outputs. A software controllable low-pass audio filter is also included.
• 512 kB of Chip RAM (150 ns access time).
• AmigaOS 1.2 or 1.3
• One double-density floppy disk drive is built in, which is completely programmable and thus can read 720 kB IBM PC disks, 880 kB standard Amiga disks, and up to 984 kB with custom formatting (such as Klaus Deppich’s diskspare.device). Uses 300 rpm and 250 kbit/s.
• Built in keyboard.
• A two-button mouse is included.