The Motherboard - Commodore Amiga 500+ User Manual

10. The Motherboard

The Amiga 500+ has had several revisions including the 8A and 8A.1. A Picture of the A500+ 8A1
revision motherboard is shown below. Very early boards still used the OCS chipset when
Commodore was trying to get rid of old stock.
From the left (top to bottom):
Denise or Super DENISE chip (39081) - supports ECS graphics supporting HAM6 (4096 colours)
and EHB (Extra half bright) for 64 colours.
Expansion slot for external Hard Drives or CD drive.
Motorola 68000 CPU - Main Central Processor
Kickstart ROM Chip - The A500 had one 512K ROM chip that held part of AmigaOS and allow the
Amiga to boot from Floppy or Hard disk.
CIA Chip (391078) - Controls ports such as Serial, Parallel and Mouse ports
PAULA (391077) - Controls the sound and the floppy drive
AGNUS chip (31069) - Supports 2MB of Chip RAM, the Blitter and 25 DMA channels (large center
chip)
CIA Chip (391078) - Second CIA chip for controlling ports
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