Introduction.

Workshop PG5
Resources
3.2.5 Texts &
Data blocks
TEXT/DB
Main memory
NV
0 3999
Extension memory NV
4000 (PCD4/6) 7999
(PCD2) 5999
(PCD1) 4999
Texts and DataBlocks (DB's ) are non volatile. Texts ( string of characters ) are
used for: Messages on displays, texts you want to send to a pager, initial
strings for modems and so on.
DB's are used for data logging, tables and so on.
Technical stuff:
Where are
Text/DB’s saved?
Register, flags, timers, and counters are handled by the system and stored in a
small RAM apart from the main memory.
DB's and texts on the other hand are stored in the main memory, together with
the user program. If you want to use a FLASH Eprom or a normal EPROM for
your main memory, remember that if you are in run mode, you can read from
this memory but not write to it. Therefore you can't alter the content of your
DB’s ( for example your Data login ). In most cases you won’t bother with
this, but if you know that you are going to read and write from your DB's, then
make sure to use DB's which are stored in the extension memory => address
4000 and up. (This is the extension memory and it is always RAM, which
means you can read and write to it).
See how a Text or DB is declared in a Instruction list program:
Example:
Declaration of
BD’s & Text
TEXT 10 "Bonjour!"
TEXT 11 [7]"Hello"
DB 12 45,46,78,999,0
DB 13 [10]
DB 14 [4] 2,3
;Text number 10 contains the string Bonjour!
;Text number 11 is 7 characters long were from
the last 5 are Hello and the first two are spaces.
;DB number 12 with the 5 integer values:
;45.46,78,999,0
;DB number 13 is 10 values long and they are
zero at start up.
;DB 14 is four values long. The first two are 2 &
3 the second ;two are 0
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