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Table 1628

Format of DOS memory control block:
Offset	Size	Description	)
 00h	BYTE	block type: 5Ah if last block in chain, otherwise 4Dh
 01h	WORD	PSP segment of owner or special flag value (see #01629)
 03h	WORD	size of memory block in paragraphs
 05h  3 BYTEs	unused by MS-DOS
		(386MAX) if locked-out block, region start/prev region end
---DOS 2.x,3.x---
 08h  8 BYTEs	unused
---DOS 4.0+ ---
 08h  8 BYTEs	ASCII program name if PSP memory block or DR DOS UMB,
		  else garbage
		null-terminated if less than 8 characters
Notes:	the next MCB is at segment (current + size + 1)
	under DOS 3.1+, the first memory block is the DOS data segment,
	  containing installable drivers, buffers, etc.	 Under DOS 4.0+ it is
	  divided into subsegments, each with its own memory control block
	  (see #01633), the first of which is at offset 0000h.
	for DOS 5+, blocks owned by DOS may have either "SC" or "SD" in bytes
	  08h and 09h.	"SC" is system code or locked-out inter-UMB memory,
	  "SD" is system data, device drivers, etc.
	Some versions of DR DOS use only seven characters of the program name,
	  placing a NUL in the eighth byte.
SeeAlso: #01630,#01632,#01633


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