simple: explain why we don't worry about disk read versus memory clear

On the Z80 and many other 8bit micros a sequential series of disk reads
(especially from CF) are as fast as a memory clear or very close to it.

The TRS80 is perhaps the obvious exception.

diff --git a/Kernel/simple.c b/Kernel/simple.c
index ea66f6d..7e225bf 100644 (file)
--- a/Kernel/simple.c
+++ b/Kernel/simple.c
@@ -19,6 +19,11 @@
  *     on switches. It makes no sense to support it here because to do that
  *     well we want to support a simple first fit allocator for swap ranges
  *     so our swap isn't huge and empty.
+ *
+ *     The fact we don't do this for 8bit systems may seem weird, but on most
+ *     of the systems supported a contiguous series of disk reads of 512
+ *     byte blocks isn't *that* much slower than a memory zero. (inir + sector
+ *     setup versus ldir on Z80 for example)
  */
 
 #include <kernel.h>