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- From: mhardy@acorn.co.uk (Michael Hardy)
- Subject: Re: Real Icon Dragging.
- Date: 8 Oct 92 09:17:36 GMT
- Organization: Acorn Computers Ltd, Cambridge, England
-
- >The easiest way (although it is cheating somewhat) is to type
- >*FX 162,28,3. This enables solid icon drags with shadows.
-
- Without wishing to sound too critical, this is not a good way to do it,
- since you are also altering the state of seven other bits which control
- other aspects of FileSwitch and the Wimp. A better way is to read the byte,
- set bit 1, and then write it back. This is the program that I use:
-
- REM Toggle state of DragASprite bit in CMOS
-
- REM Read byte
- SYS "OS_Byte",161,&1C TO ,,byte%
- REM EOR byte with mask for bit 1
- byte% = byte% EOR 1<<1
- REM Write byte back again
- SYS "OS_Byte",162,&1C,byte%
- END
-
- You *must* use the OS_Byte calls, otherwise the checksum byte will become
- incorrect. This byte is calculated on a power-on reset, and then maintained
- by the OS_Byte calls (in other words, they don't recalculate it, but merely
- update it in a manner that is appropriate to the changes made).
-
- The other thing to note is that you *must* do a power-on reset when
- upgrading from RISC OS 2 to RISC OS 3, not just to initialise the checksum,
- but more importantly because the CMOS usage differs between the versions.
-
- - Michael J Hardy
-
-