XMODEM write to HDD thrashes the HDD head

[eyalabraham]

XMODEM write to HDD thrashes the HDD head every 1K write.
Think I need a different write-at-once block size for HDD vs. Mem. maybe 32 or 63K for HDD and 1K for memory writes.

11/13/13, branch "xmodem"
(1) added capability to have different buffer sizes for memory vs. HDD write. Allowing HDD buffer to be larger and accumulate more data for writing at-once.
(2) need to consider adding an HDD 'Seek' command."

11/18/13, branch 'xmodem'
implemented (1) above as a fixed 1 x 512B block for memory writes and an optional parameter block-count for HDD writes; works nicely for HDD as writes are now grouped, for example: if count is 8, write to HDD are at 4KB intervals/chunks
didn't add (2)