Remote Processing BASIC 52 - Manual (Page 102)

RPBASIC-52 PROGRAMMING GUIDE
2-83
POKEB
Syntax: P O K E B segmen t,address,d ata
Where: segment = 0 to 7, specifies a 64K segment
address = 0 to 65535, specifies address in a segment
data = 0 to 2 5 5, n um b e r t o sa v e to R A M
Function: W r it es on e da ta b yt e t o R A M .
Mode: Comm and, Run
Use: POK E B1 ,2100,D
Cards: All
D E S C R IP T I ON
Use POKE B to write to any one of 512K memory locations. The maximum number of
locations is limited by the amount of RAM installed.
WARNING: RPBASIC-52 does not check the address . It is possible to poke into the
program, stack , or variable areas. Re sults are unpredicta ble. Poke into
memory above M TOP for safest operation.
PEE K and POK E state men ts and fu nction s acce ss me mory by spe cifying a segm ent an d an ad dress. A
s e g m en t is a 65 , 53 5 b yt e bl o ck . T he l ar g es t se g m e nt n um b e r a l lo w e d de p e nd s up o n th e a m ou n t o f R A M
installed. A system with 32K of RAM can only acc ess 1 segm ent, numbe red segme nt 0. When 128K is
installe d, two segm ents, 0 a nd 1, are acce ssible. A 512K system has 8 se gme nts, num bered 0 throu gh 7.
Ano ther w ay of lo oking at a seg men t is its ad dress e quiva lent. T he gen eral ad dressin g form is: S,A AA A. S
is the se gme nt and AA AA is the ad dress.
RPBAS IC-52 always uses segment 0 for variable and program storage. Setting MTOP to a number below the
t op o f R A M e ns u re s th a t R P B A SI C -5 2 wi ll no t u s e t he m e m or y a b ov e th a t a d dr e ss . I n a 3 2K R A M s ys te m ,
the top of memory is address 32767. In a 128K or larger system, it is 65535. In 128K or 512K systems, all of
the memory in segment 1 and higher is available for data storage.
M a x im u m segment and address for a given system RAM size are:
R A M Maximum Maximum
Size Segment Address
32K 0 32767
128K 1 65535
512K 7 65535
RELATED
P E E K B , X B Y
ERRORS
B A D S Y N T A X If B, segment, ad dress, or data is missing.
BAD DATA If segment is > 7, address > 655 35 or ne gative , data > 255 or negative.
EXAMPLES
10 POKE B0,64000,D Pokes to segment 0, address 64000
20 POKE W1,0,A Pokes a word (2 bytes) to segm ent 1, address 0
30 POKE $2,30,$(1) Pokes a string to segment 2, address 30.