Radio Shack TRS-80, Service Manual, Page: 6 / 44

– 6 –
MEMORY MAP
Hex Address
C000 - FFFF 16K ROM (only 8K used)
9000 - BFFF 16K I/O Slot (Keyboard and VDG control)
4000 - 8FFF 16K RAM (4K - 20K used)
0100 - 3FFF Not Used
0080 - 00FF RAM internal to the 6803
0015 - 007F Not Used
0014 RAM Control Register
0013 Not Used
0012 Not Used
0011 Not Used
0010 Not Used
000F Port 3 Control and Status Register
000E Input Capture Register (low byte)
000D Input Capture Register (high byte)
000C Output Compare Register (low byte)
000B Output Compare Register (high byte)
000A Counter (low byte)
0009 Counter (high byte)
0008 Timer Control and Status Register
0007 Not Used
0006 Not Used
0005 Not Used
0004 Not Used
0003 Miscellaneous I/O Data Register
0002 Keyboard Output Lines
0001 Data Direction Register for miscellaneous I/O
0000 Data Direction Register for keyboard lines