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TI486 Microprocessor - Al Kossow's Bitsavers

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Address Spaces<br />

2.4 Address Spaces<br />

The <strong>TI486</strong> can directly address either memory or 1/0 space. Figure 2-18 and<br />

Figure 2-19 illustrate the range of addresses available for memory address<br />

space and 1/0 address space. For the <strong>TI486</strong>SLC/E, the addresses for physical<br />

memory range between 00 OOOOh and FF FFFFh (16 MBytes). For the<br />

<strong>TI486</strong>DLC/E, the addresses for physical memory range between 0000 OOOOh<br />

and FFFF FFFFh (4 GBytes). The accessible 1/0 addresses space for both the<br />

<strong>TI486</strong>SLC/E and <strong>TI486</strong>DLC/E ranges between 00 OOOOh and 00 FFFFh (64<br />

KBytes). The coprocessor communication space for the <strong>TI486</strong>SLC/E exists in<br />

upper 1/0 space between 80 00F8h and 80 OOFFh. The coprocessor<br />

communication space for the <strong>TI486</strong>DLC/E exists in the upper 1/0 space<br />

between 8000 00F8h and 8000 OOFFh. These coprocessor 1/0 ports are<br />

automatically accessed by the CPU whenever an ESC opcode is executed.<br />

The 1/0 locations 22h and 23h are used for <strong>TI486</strong>SLC/E and <strong>TI486</strong>DLC/E<br />

configuration register access.<br />

Figure 2-18. <strong>TI486</strong>SLCIE Memory and 110 Address Spaces<br />

FF FFFFh<br />

Physical<br />

Memory Space<br />

FF FFFFh<br />

Accessible<br />

Programmed<br />

1/0 Space<br />

Physical<br />

Memory<br />

16 MBytes<br />

8000FFh<br />

8000F8h<br />

..-- Coprocessor<br />

Space<br />

00 OOOOh 1..-_____ .....<br />

00 FFFFh<br />

_----111..--<br />

<strong>TI486</strong><br />

00 OOOOh 1..-_____ .....<br />

Configuration<br />

Register 1/0<br />

Space<br />

000023h<br />

000022h<br />

2-37

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