Сообщение от
goodboy
Bit 6 of IN-Port 0xfe is the EAR input bit. The value read from this port is not trivial, as can be seen from the following program:
10 OUT 254,BIN 11101111
20 PRINT IN 254
30 OUT 254,BIN 11111111
40 PRINT IN 254
50 GOTO 10
For a correct test do not press any key while running, and have no EAR input.
If the output is 191,255,191,255 etc, you are on real Spectrum Issue 3.
If output is always 191 or always 255, change the value in line 10 to BIN 11100111.
If output is then 191,255,191,255 etc, then you are on Spectrum Issue 2.
If output is still always 191 or always 255 you are on Spectrum emulator.