F2 keys. It sold in Radio Shack stores and Tandy Computer Centers for $219.95. The CoCo 3 is compatible with most older software and CoCo 2 peripherals. The 6809 in the CoCo 1 and 2 runs at 0.895 MHz. The CoCo 3 runs at that frequency by default, but is software controllable to run at twice that rate; OS-9 takes advantage of that capability. Taking the place of the graphics and memory hardware in the CoCo 1 and 2 is an application-specific integrated circuit called the GIME (Graphics Interrupt Memory Enhancement) chip. The GIME also provides: Output to a composite video monitor or analog RGB monitor, in addition to the CoCo 1 and 2's TV output. This improves the clarity of its output. A paged memory management unit breaks up the 6809's 64 KB address space into chunks. The scheme would later allow third party RAM upgrades of up to 2 MB (). Text display with real lowercase at 32, 40, 64, or 80 characters per line and between 16 and 24 lines per screen. Text character attributes, including 8 foreground and 8 background colors, underline, and blink. New graphics resolutions of 160, 256, 320 or 640 pixels wide by 192 to 225 lines. 320x192x4, 320x192x16, 640x192x2, and 640x192x4 from a palette of 64 colors. There are two palette modes - RGB (3 base colors with 3 levels of intensity and white, black and two gray tones) and Composite (16 distinct colors with 4 levels of intensity). Omitted from the GIME are the seldom-used SAM-created Semigraphics 8, 12, and 24 modes. A rumored 256-color mode (detailed in the original Tandy spec for the GIME) has never been found. Previous versions of the CoCo ROM were licensed from Microsoft, but Tandy could not convince them to provide further BASIC updates. Instead, Microware provided extensions to Extended Color BASIC to support the new display modes. To not violate the spirit of the licensing agreement between Microsoft and Tandy, Microsoft's unmodified BASIC is loaded in the CoCo 3's ROM. Upon startup, the ROM is copied to RAM and patched by Microware's code. The patched code has several bugs, and support for many of the new hardware features is incomplete. Microware also provided a version of the OS-9 Level 2 operating system shortly after launch. OS-9 uses memory-mapping (so each process has its own memory space up to 64K), windowed display, and a more