The BBC and Master Computer Public Domain Library
BF66 Detect Tube presence
Submitted by Steve Fewell
Description:
Call OSBYTE &EA with Y = #&FF to detect Tube presence.
Transfer the result to A, which will contain the following on return:
0 - If no Tube is present
255 - If Tube is present
Disassembly for the Detect Tube presence routine
|
|
169 234 |
A9 EA |
LDA#&EA |
|
|
BF68 |
|
162 000 |
A2 00 |
LDX#&00 |
|
BF6A |
|
160 255 |
A0 FF |
LDY#&FF |
|
BF6C |
|
032 244 255 |
20 F4 FF |
JSR &FFF4 OSBYTE |
|
BF6F |
|
138 |
8A |
TXA |
|
BF70 |
` |
96 |
60 |
RTS |
