I certainly don't recall this at the time, but I'll ask to be sure.
According to the GW-BASIC documentation, a semicolon between the INPUT prompt and the variable suppresses the question-mark prompt.
I do not believe this was the case on the Apple or PET/C64, anyone have a sim handy to try?
My interpreter is coming along, if I get another day or two free I'll post it for people to try.
The comma syntax does not work in Commodore BASIC, neither on the PET (Commodore BASIC V4.0), nor on C64 (Commodore BASIC V2.0), C16/116 (Commodore BASIC V3.5) or Commodore 128 (Commodore BASIC V7.0). Using a construction like INPUT "ENTER SOMETHING",A$ yields a SYNTAX ERROR. There are however other ways to suppress the question mark prompt on a C64, see the answers to this question.
INPUT "ENTER SOMETHING";A$ (with a semicolon) would be a valid statement when used in a program line.
INPUT with comma vs. semi
I'm not sure what this is supposed to ask, but ...
According to the GW-BASIC documentation, a semicolon between the INPUT prompt and the variable suppresses the question-mark prompt.
I do not believe this was the case on the Apple or PET/C64,
It was on the Apple and all other MS-BASIC versions, but not on the PET.
Examples:
10 INPUT A
20 INPUT "NUMBER"; A
10 INPUT ""; A
will display on an Apple II ("_ "being the cursor)
?_
NUMBER_
_
while the PET does always give the question mark and a space
? _
NUMBER? _
? _
In addition maybe relevant here that the ECMA-55 (1978) standard "For minimal BASIC" (adopted by ANSI as ANSI X3.60-1978) makes the whole prompt implementation defined and optional, while recommending:
It is recommended that the input-prompt consists of a question-
mark followed by a single space.
So Commodore's implementation is close to standard .. albeit I'm not sure if by purpose.
[Also, if you're about to write any new BASIC, make sure it is able to handle ECMA-55 programs as means for general compatibility. The National Bureau of Standards' Minimal BASIC Test Suite might be of help]
Later ECMA-116 defines that
If an input-prompt specifier is present in the input-statement, then
the implementation-defined input-promt shall not be output;
Though, it also requests a quite different syntax using keywords and a colon to seperate between modifiers and variable list:
INPUT PROMT "Name? ": A$
While using a keyword does allow for a prompt to be supplied in a string variable, the colon may tick off many. ECMA-116 is eventually a great language definition, but came way to late for any influence.
Input in (early) MS BASIC has another nice side effect when using the notation without assigning a prompt. A statement like
INPUT ;A
which should produce a syntax error right away when executed, will still first prompt for a value, only to break after it has been entered.
