Remote-processing RPC-150 Manuale Utente Scaricare il pdf (Pagina 15)

CHAPTER 5 DATA MEMORY

RPC-150 Page 13

50 B = PEEK(60000)

You can store and retrieve arrays, strings, and variables

in this way. There ar e many variations of PEE K and

POKE statements. A list of CAMBASIC commands

appears at the end of this chapter.

ASSEMBLY LANGUAGE INTERFACE

Use the CAMBASIC CALL statement to execute an

assembly or C language program.

A specific area of RAM should be reserved for the

program. This is to prevent strings and variables from

corrupting that area of RAM . Use the SYS(1) and

SYS(2) statements to do this. SYS(1) returns the low

memory location while SYS(2)-500 returns the upper

location. Run the program first to make sure variable

memory has been allocated before running these SYS

commands. F ailure to do so may r esult in address

returned that are not really free for assembly language

program s.

There are sever al ways to put a program in mem ory,

depending upon your application.

1. Use DATA statements and POKE the code into

segment 0 RAM.

2. Write a program to download code. Some

applications are connected to a larger system which

"initializes" its systems. Using INKEY $ or COM $,

code is received and then poked into memory using

POKE$.

3. Read the code from the EPROM (U3) (using INP)

and transfer it to RAM (using POKE ). Y ou would

have to use an external programmer to place the

code above CAMBASIC code.

In all cases, it is best to load code into RAM from a

"secure" source. E ven though RAM is battery backed,

over time there is the possibility it could be corrupted.

Below is an example of loading and running an asse mbly

language program.

100 FOR N = &FB00 TO &FB0C

110 READ A

120 POKE N,A

130 NEXT

900 DATA &DB, 2, &47, &E6, &FE, &D3

910 DATA 2, &78, &F6, 1, &D3, 2, &C9

2000 CALL &FB00

Lines 100 to 130 load the program into RAM.

Line 2000 calls the program. It toggles J2 line 13.

COMMANDS

The following is a list of CAMBASIC commands used

with RAM.

Command Function

CALL Calls an assembly language routine

CLEAR Clears strings and allocates string space

PEEK Returns a byte

DPEEK Returns a 16 bit value

PEEK$ Returns a string

FPEEK Returns a floating point number

POKE Stores a by te

DPOKE Stores a 16 bit value

POKE$ Stores a string

FPOKE Stores a floating point number

1 2 ... 10 11 12 13 14 15 16 17 18 19 20 ... 25 26

Commenti su questo manuale

Nessun commento

Remote-processing RPC-150 Manuale Utente Pagina 15

Commenti su questo manuale

Prodotti e manuali riguardandi Computer Remote-processing RPC-150