[FRAM71] Pre-Production Batch

[Hans Brueggemann]

(12-14-2014 12:40 AM)rprosperi Wrote:  Reconfiguring the IRAMs to ROM will protect the port contents from errant code romping thru memory. For example when playing with Forth (or even some unknown LEX files) I've trashed the contents of IRAM ports, but the "ROM" ports are preserved as-is. Basically this really just saves the time needed to ROMCOPY the port's content back to what it was, but it takes a lot less time to just POKE the revised FRAM config string to make them ROM one time, than rebuilding the IRAMs each time it gets destroyed.

exactly this. while FREE PORT (5.xy) mimics the freed RAM portion into soft configured ROM and hence protects its contents from a MEMORY LOST, it can't protect its contents against alterations that result from POKE operations. using FRAM71s configuration area to re-define portions of RAM to soft configured ROM sets FRAM71s internal read-only flag on that area which gives a better protection against overwrites, albeit not perfect, as the configuration area itself remains unprotected. also, doing POKE into an IRAM area will work without notice, while trying to POKE into a ROM-declared RAM area will result in "ILLEGAL ACCESS".


hans