-----Oorspronkelijk bericht-----
Van: Antoni Burguera <[EMAIL PROTECTED]>
Aan: [EMAIL PROTECTED] <[EMAIL PROTECTED]>
Datum: zaterdag 13 juni 1998 11:16
Onderwerp: RE: Assembler programming
:>>The
:>>specification of this routine says that the slot may be specified in the
8
:>>order bits of the iy register... why the iy register has been loaded with
:>>the content of the addres 0faf7??
:>
:>0FF7 is MSX2 system variable (EXBRSA) containing the MSX2 subrom slot id.
:
:The MSX2 Technical Handbook sais:
:
:AVCSAV (FAF7H, 1)
: contents: reserves AV control port
:
:
:EXBRSA (FAF8H, 1)
: contents: SUB-ROM slot address
:
:Then, the EXBRSA is the FAF8, not FAF7. There is an error in the assembler
:listing, or in my version of the Technical Handbook?
EXBRSA is a one-byte data. The routine expects this data to be in the high
part (the IYh (I)-part) If you load it into IY from FAF7, then the data of
FAF7 will be loaded in IYl, and will have no use but dummy. The data of FAF8
will be loaded in the IYh-register.
:>>* Is the 085h the routine to draw a line? It isn't specified in the
:>>Technical Handbook.
:>
:>Yes, it is !
:
:Where can I find the specification of this routines? In the MSX2 Technical
:Handbook I have, the NVBXLN (draw a box) routine is specified, but the
line
:routine isn't.
MSX-Basic subrom-routines are not located on fixed adresses. Calling them
MAY cause incompatibility when using a higher version of Basic. It's better
and faster to draw a line via the VDP-commando's manually.
~Grauw
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