This tiny util was in request to a
letter I received some time back. I
wrote this program and sent it back
as my reply, but somehow never got
around to sending it in.
What it does - well, some software
uses *FX200 to ensure that it is
wiped from memory after you press
break. This stops people from typing
OLD then LIST.
This is sometimes of annoyance so
to prevent this my patch discards all
It will not however work if the programmer
is cunning enough to restore the
default vector tables when starting
up, as my patch will be bypassed!
See how you go anyway.
It's assembled at &C00, but if this
causes problems send £2.50 to my
usual address and I'll post a disk
back with a custom version.
I find several instances when
transferring programs between machines
that the LOAD and EXEC addresses are
wrong and I need some way of altering
them without having to load the file
into memory and resaving it.
Obviously this is not practical if the
file is larger than the beeb's memory.
Running this BASIC program solves
First,the filename is checked and the
current options displayed,you may then
re enter ones that you find more
The ACCESS number is filing system
dependant,as not all FS's have all the
bits available.eg. DFS reserves just one
bit for the purpose, Locked, on not!
I advise you just copy the number and
keep it the same.
This program comes off my 'frequently
used stuff' disk, and I find it almost
essential to the course of debugging.
Essentially it allows you to trap a
vector and display on the screen the
values of A,X,Y that were present
when the call was made.
The routine then passes on the value
and all continues as normal.
Ones of note, try trapping OSByte
vector (at &20A) then catalogueing a
disk - hundreds of OSBytes fly past
as the DFS doesn't call OSWriteChar
directly but goes via it's own routine
which changes the FX3 (set output
destination) settings for EVERY letter.
Mad. I must advise that you don't try
trapping any of the character output
vectors, to avoid paradox.
6 Bollinbrook road
8BSmail - D6G
EDITOR.... Thanks for your lovely submissions Robert!