HP Vectra Technical Reference Manual page 308

This function gets the segment pointers of the EX-BIOS free RAM area. Two pointers are
returned
by
this function call, the "last used OS" pointer marks the first paragraph of EX-BIOS
RAM that is free for use. The "max OS" pointer marks the lowest value that "last used DS" can
have. Figure 9.1 shows how the EX-BIOS memory is organized.
See the F _RAM_RET memory function.
On Entry: BP
=
V_SYSTEM (12H)
AH
=
F_RAM_GET (1 EH)
On Exit: AH
=
RS_SUCCESSFUL
BX
=
"last used OS"
OX
=
"max OS"
Registers Altered: AH, BP, DS, BX, OX
Sets the "last used DS" and "max OS" EX-BIOS pointers to the values passed in the BX and OX
registers. This allows the calling routine to reserve a piece of the EX-BIOS memory.
Caution
The F_INS_FIXGETOS and F_INS_FREEGETOS functions described above also mod-
ify these values. Use caution when allocating memory with both methods.
On Entry:
BP
=
V_SYSTEM (12H)
AH
=
F_RAM_GET(20H)
BX
=
"last used OS"
OX
=
"max OS"
On Exit: AH
=
RS_SUCCESSFUL
Registers Altered: AH, BP, OS
"",.. Example: The following code allocates five paragraphs (80 bytes) of EX-BIOS memory.
Get the memory pointers first.
MOV BP, V_SYSTEM
MOV AH, FJAM_GET
,. HP vector 12H.
,. function
1
EH
System Drivers 299