Remote-processing RPC-2350 Manuel d'utilisateur télécharger pdf (Page 18)

CHAPTER 3 SAVING AND LINKING PROGRAMS

3-3

SAVING DATA TO FLASH EPROM

Additional data, such as strings and constants, can be

saved to U3 using a variation of the SAVE command.

Exactly how much memory you have depends upon how

many and how large of program(s) you have.

Flash sector size must be considered when saving. The

sector size determines the minimum write ar ea. Thus, if

you were to save just 1 byte, 128 (29C010A type) or 256

(29C040A) bytes w ill be written. All unwritten data is

saved as FFH.

Font are stored starting at address &AC00, segment 9.

This is above program area 1. If space is tight, consider

using a 512K Flash.

Chapter 5 treats saving data to RAM and Flash more

extensively.

INSTALLING 128K OR 512K FLASH

Socket U3 can hold a 128K or 512K Flash EPROM.

Perform the following steps to install a a new Flash:

1) Remove power from board and r emove existing

EPROM from U3.

2) Orient the new Flash so pin 1 is near the edge

of the board. Install the IC.

3) Set jumper W2 according to memory size:

W2[4-5] 128K (29C010A, 29C010)

W2[5-6] 512K (29C040A)

LINKING PROGRAMS

One CAMBASIC program can load and run another.

For example, the autorun program can, at some point,

run the program in Flash area 1, which can then call the

original one. Using this technique, you can have

program sizes of nearly 70K bytes using a 128K Flash or

245K using a 512K Flash..

This linking is intended to be called occasionally

(although we have run programs that have linked

millions of times). For example, the second pr ogram is

a set up and calibration routine. This will fr ee up ma in

program RAM for variables.

Linking in CAMBASIC is not threaded code. It does

replace one program with another while keeping

variables.

When developing programs and testing for linking, make

sure you save any changes to Flash before running. Any

changes in program length, especially the first (autorun)

one, can have adver se, strange, or disastrous results.

When you have saved the changes, press the reset button

to simulate an autorun. NEVER start with program 1

(LOAD 1) then have it load program 0.

There are other do’s and don’ts, precautions and

limitations to linking. They are discussed below.

Program size

The first (autorun) program run MUST be larger than

the second, linked program. This is because variables

and data are stored above the program. If the second

program was longer, it would wipe them out. To simply

increase program size, add co mments.

Multi-tasking

All multitasking (ON BIT, ON COM$, COUNT, etc.)

and interrupts are disabled and multi-tasking data cleared

(hash table is zeroed out) when a program is linked.

You must re-enable them in your code. The reason for

this is the operating system stores the address (not line

number) to execute. When you chan ge progr ams,

addresses change.

You can save some selected data by writing it to a

variable. For example, the current count can be saved

just before you LOAD 1 RUN. You will need to re-

enable the count when you enter the program.

DATA statements

Use RESTORE to reset the DATA statement pointer

every time you enter a program (if you are using DATA

statements).

Linking within the program

To link to another program , execute

LOAD n RUN

on its own line. Do not put any other code after it. Do

not make it as part of a conditional statem ent, as in

IF A = N THEN LOAD 1 RUN

If you link within a subroutine, DO..U NTIL, or

FOR..NEXT, execute EXIT CLEAR before LOAD.

2250 GOSUB 7000

1 2 ... 13 14 15 16 17 18 19 20 21 22 23 ... 82 83

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Remote-processing RPC-2350 Manuel d'utilisateur Page 18

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