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No screen  -  Am I at a DOS prompt, or am I in Cassette BASIC ?



Note that if you have an IBM 51xx computer, and you heard {two short beeps} during the power-on self test (POST), that means that an error occured, and unknown to you, the POST is prompting you with "ERROR. (RESUME = F1 KEY)".  In which case, obviously, press the F1 key to allow the computer to continue the boot process.


DOS

If typing the following sequence of keys results in a beep, you are at a DOS prompt:

1.  Press [e]
2.  Press [c]
3.  Press [h]
4.  Press [o]
5.  Press the space bar
6.  Momentarily press [g] whilst the [CTRL] key is being held down
7.  Press [ENTER]


Note:  You may not hear a beep because DOS started, then ran something like a menu program (i.e. you are not at a DOS prompt).

Note:  Simply pressing CTRL-G only (no 'echo ' in front) works in some versions of DOS, but not others.  (IBM DOS 3.3 = Yes, MS-DOS 6.22 = No)

Technical:  What you are doing is sending a CTRL-G character to the console.  CTRL-G results in the byte of 07, which is the BELL character in ASCII.



Cassette BASIC

If entering (i.e. press ENTER after typing in the line) the following results in a beep, you are in Cassette BASIC:

print chr$(7)