Advertisement
OTHER SYSTEM FUNCTIONS
EXIT CONDITIONS:
A
is
unchanged.
B
is unchanged.
27.1 -- Register Functions
X is shifted left one bit position.
Bit
zero is rilled with zero.
e
contains
bit 15 of the entry value of
Xo
The
remainder
of
CC
is
indeterminate.
27.1.15 Push X
on stack -- .PSHX
The .PSHX
function pushes the contents
Or
the X register
on the current stack.
ENTRY PARAMETERS:
EXIT
CONDITIONS;
None.
A is unchanged.
B is
unchanged.
X is
unchanged.
CC
is unchanged.
S
has
been
dec~emented
by
2.
The
contents
or
XL
have been pushed on
the stack followed by the contents oT
XH.
27.
1.
16 Pu 11 X from stac k -- . PULX
The
. PULX
function
pulls
the contents from the stack
into the X register.
ENTRY PARAMETERS:
EXIT CONDITIONS:
None.
A is unchanged.
B
is unchanged.
XH contains the contents located
at
the
entry
value of S + 1.
XL
contains
the contents located at the
entry value
01
S
+
2.
CC
is
unchanged.
S has been incremented
by
2.
27.2 Double-byte Arithmetic Functions
The double-byte arithmetic functions are used by some oT
the
other
system
functions
and
the
MDOS
commands as an
extension of the M6800 instruction set.
These functions
are
not
as
general
purpose as the register functions,
but they
are useful in special cases.
c..........
~7_l'\L.
Advertisement
