Introduction.

Workshop PG5
Getting Started - Project management
EXTENSION MEMORY?
Although this point is handled automatically by the configurator, it might
be interesting to know what extension memory is all about:
All the PCD's have sockets where the user can place additional memory.
The user has three options; RAM, EPROM, or FLASH. Some PCD's
have RAM (PCD1 and PCD2 ) already soldered on the PC-Board itself. In
the case of PCD2, the RAM has a content of 32kByte or 128kByte depending
on the hardware version. Depending on your program size, it
may not be necessary to place a memory chip into the empty socket. You
can load your programs into this RAM and work without an additional
RAM or EPROM chip.
If you want your program to be stored on an EPROM, FLASH, or if you
have a large program which is to large for the standard RAM, then you
will have to add an additional memory chip. As soon you place a memory
chip into the empty socket, this memory becomes the main memory and
the small RAM becomes the extension memory. Complicated? A little?
Why bother? Well for one, you now know what this extension memory is
and, if for example, you have your program on an EPROM and you want
to change the content of a DB in the run mode. In such a situation the DB's
in the EPROM can't be changed and the only RAM you'll have will be this
small extension memory. DB stands for Data Blocks, and will be covered
in chapter 3.
© Saia-Burgess Controls Ltd. Page 1-16