50
All
and more about Sharp
PC
-1
500
at http:/lwww.PC-1500.info
® VEJ (VEctor subroutine Jump)
One
step s
ub
rou
tine j
ump
instruct
io
n t
hat
jum
ps to the address indicated by t
he
two-
byte ve
ctor
. whose high or
der
addr
ess byte is re
pr
esented by
FF
H and l
ow
order
a
ddr
ess byte by
the
operand
of
the instru
ct
ion.
The flag
Z is re
se
t.
There
are
28
kinds of VEJ operand within two bytes range
of
11
000000
(C
OH)
l o
1111
01
10
(F6H
).
The
refore. the vector address table
conta
ins the
addr
ess ar
ea
of
FF
C
OH
to
FFF
6H.
•Format
VEJ i
•Operat
i
on
PL - (S)
S - 1- S
PH
- (S)
S - I - S
(
FF
OOH
+
i)
- PH
(FFOO
H+i+ I) - PL
NO
TE
: i has 28 kinds of VEJ
ope
r
ands.
(
EX
) VEJ C4H
The
co
ntents of FFC4H
an
d FFCSH are
V
ecto
r
inte
rr
ogated
at
the address 4000H and
subroutine
1u
m
ti
j
ump
to
t
he
su
br
ou
ti
ne
of 4500H.
With the R
TN
instruction of the
s
ub
routin
e.
til
e ex
ec
ution res
um
es fr
om
the address 4001 H again.
Because it permits subroutine
jU1m
p
by
a
single
by
te
of
inst
ru
ct
ion. it
he
l
ps
to
reduce
program steps. when
app
li
ed
to
too
ofte
n appearing s
ub
routine.
Do
not sell this PDF !! !
lnstr
-.i
c
t1
on
exec
ut
i
on
l
<!)OOH
C4H
V(J 1nslr
uie
ti
on
lnst1ucflon
..,
4001H
execu
h
on
!
~e!u11\
4
500H
S1.1btou1i
ne
processing
RTN
::::::--..._
F
FC4
H
45H
fFC5H
OOH
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