3. The command "CURSOR #n, a, b, c, d" is not accepted.
Clue: "CURSOR #n, a, b, c, d" gives "bad parameter" (NB: message "channel not open" is NOT a bug).
4. If an expression in a DATA statement starts with a bracket [(], the rest of the DATA line is ignored.
Clue: DATA ...., ( ...),
5. GOSUB in short FOR loops can act as ENDFOR.
Clue: GOSUB in a short FOR loop.
6. If you ask for DIR mdv8_, then DIR mdv2_ will not work properly thereafter.
Clue: DIR mdv8_
NOTE: A bad microdrive 2 can cause the same symptoms, so beware!
7. If a program aborts in the middle of a PROCedure, and you type EDIT, you get "not implemented", and you are left editing a spurious line
number.
Clue: EDITing PROCedures.
8. Sometimes variable names get over-written by the word "PRINT". This is random, so far as we know.
Clue: "PRINT" in unexpected places.
9. If you declare more than 9 local variables, all sorts of unexpected things can come up on the screen.
Clue: LOCal a, b, c, d, e, f, g, h, i, j, ...
Note that if the "fault" can be repeatedly demonstrated on the customer's QL, but not on another one with the same RDM version, then it is not a
bug.
If the fault cannot be reproduced at all on the customer's QL, then it MAY be a random bug (e.g. item (h) above), but this is most unlikely.
2.2 In some circumstances, the use of slices of strings leads to memory being allocated which cannot be reclaimed without the use of CLEAR.
Either of these will run out of memory eventually:
10 DIM a$(10,10)
20 a$(5) = "hello"
30 REPeat x: PRINT a$(5, 1 TO 4)
or
30 REPeat x: PRINT a$(5)(1 TO 4)
2.3 CLEAR, LOAD or NEW are the only ways of getting this memory back; these commands delete all the variables. (Remember that RUN on its
own leaves variables untouched - put a CLEAR and/or restore at the start of your program if you need to). To avoid this problem, use:
30 REPeat x: temp$=a$(5): PRINT temp$(1 TO 4)
This problem only arises with string arrays, not with numerical ones.
2.4 One bug has inadvertently been introduced into the QL with the introduction of the JS ROM. in a procedure, if you SELect ON one of the
parameters of the procedure, you get "bad name", unless you are SELecting ON the last one.
i.e. DEF PROCedure f(x,y)
...
SELect ON x gives "bad name"
SELect ON y is OK.
This bug is only present in the JS ROM. You should also note that you cannot SELect ON a character string.
2.5 Another obscure bug on the QL is as follows. If you ever open the SER2 port, either by an explicit OPEN command, or indirectly by LOAD,
COPY, SAVE etc, please note that the channel can never be properly closed again, even using the CLOSE command. In fact CLOSE (SER2)
closes SER2 output and SER1 input.
2.6 One effect of this is that if you subsequently input data via SER1, and you have a device that is also trying to send to SER2, the data streams
will get muddled. One way round the problem is to unplug the lead from SER2 when not in use. This bug is present on all current versions of ROM
(AH, JM and JS).
3. PRINTING PROBLEMS
3.1 If a customer complains that his printer will not print more than about a page of output from his QL, he should check the wiring in the lead.
3.2 Many printers require the DTR line to be connected to pin 20. Some of these, by chance, work with the DTR line connected to pin 4, until one
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