F0-FF HEX
These key codes are used for keyboard to 68000 communication, and are not associated
with a keystroke. They have no key transition flag, and are therefore described completely
by 8-bit codes:
78 Reset warning. CTRL-AMIGA-AMIGA has been pressed. The keyboard will
wait a maximum of 10 seconds before resetting the machine. (Not
available on all keyboard models)
F9 Last key code bad, next key is same code retransmitted
FA Keyboard key buffer overflow
FC Keyboard self-test fail. Also, the caps-lock LED will blink to
indicate the source of the error. Once for ROM failure, twice for
RAM failure and three times if the watchdog timer fails to
function.
FD Initiate power-up key stream (for keys held or stuck at power on)
FE Terminate power-up key stream.
These key codes will usually be filtered out by keyboard drivers.
LIMITATIONS OF THE KEYBOARD
The Amiga keyboard is a matrix of rows and columns with a key switch at each
intersection (see Appendix H for a diagram of the matrix). Because of this, the keyboard is
subject to a phenomenon called "phantom keystrokes." While this is generally not a
problem for typing, games may require several keys be independently held down at once.
By examining the matrix, you can determine which keys may interfere with each other,
and which ones are always safe.
Phantom keystrokes occur when certain combinations of keys pressed are pressed
simultaneously. For example, hold the "A" and "S" keys down simultaneously. Notice that
"A" and "S" are transmitted. While still holding them down, press "Z". On the original
Amiga 1000 keyboard, both the "Z" and a ghost ''X" would be generated. Starting with the
Amiga 500, the controller was upgraded to notice simple phantom situations like the one
above; instead of generating a ghost, the controller will hold off sending any character
until the matrix has cleared (releasing "A" or "S" would clear the matrix). Some high-end
Amiga keyboards may implement true "N-key rollover," where any combination of keys
can be detected simultaneously.
- Interface Hardware 247 -
Summary of Contents for Amiga A1000
Page 1: ...AMIGA HARDWARE REFERENCE MANUAL 1992 Commodore Business Machines Amiga 1200 PAL...
Page 20: ...Figure 1 1 Block Diagram for the Amiga Computer Family Introduction 11...
Page 21: ...12 Introduction...
Page 72: ...Figure 3 12 A dual Playfield display Playfield Hardware 63...
Page 87: ...Figure 3 24 Horizontal Scrolling 78 playfield hardware...
Page 101: ...92 Playfield Hardware...
Page 199: ...Figure 6 9 DMA time slot allocation 190 Blitter hardware...
Page 203: ...Figure 6 13 Blitter Block Diagram 194 Blitter Hardware...
Page 229: ...220 System Control Hardware...
Page 246: ...Figure 8 8 Chinon Timing diagram cont Interface Hardware 237...
Page 265: ...256 Interface Hardware...
Page 289: ...280 Appendix A...
Page 297: ...288 Appendix B...
Page 298: ...APPENDIX C CUSTOM CHIP PIN ALLOCATION LIST NOTE Means an active low signal Appendix C 289...
Page 302: ...APPENDIX D SYSTEM MEMORY MAP Appendix D 293...
Page 343: ...334 Appendix F...
Page 351: ...342 Appendix G...
Page 361: ...352 Appendix H...
Page 367: ...358 Appendix I...
