Deadlock

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Sun: Expert C Programming

Expert C Programming
Deep C Secrets by Peter van der LindenISBN 0-13-177429-8
http://www.sun.com/971124/cover-linden/cchap.html

Dynamic C - For embedded systems

http://www.rabbitsemiconductor.com/documentation/docs/manuals/DC/DCUserManual/

Dos Memory Map

http://www.frick-cpa.com/dos/DOS_Memory_1.asp#1
http://www.osdata.com/system/physical/memmap.htm

PC-DOS and MS-DOS memory map

PC-DOS and MS-DOS memory map

high memory
segment	offset	size	contents
0000h	0000h	1024	interrupt vector table
	0400h	172	BIOS communication area
	04ACh	68	reserved by IBM
	04F0h	16	user communication area
	0500h	256	DOS communication area
	0600h	varies	operating system: IBMBIO.COM (DOS interface to the BIOS) IBMDOS.COM (DOS interrupt handlers and interrupt 21h service routines DOS buffers, control areas, and device drivers COMMAND.COM (resident portion), interrupt 22h, 23h, and 24h handlers, routine to reload transient portion of COMMAND.COM memory-resident utilities transient applications transient portion of COMMAND.COM
9000h	FFFFh		highest address of user memory
A000h	0000h	128K	reserved area of ROM
A000h	0000h		beginning of area used by EGA and PS/2 video systems
B000h	0000h	4000	monochrome video memory
	0800h	16K	color graphics adaptor (CGA) video memory
C000h	0000h	192K	ROM expansion and control area
	8000h		ROM for hard disk
D000h			ROM expansion and control area
E000h			ROM expansion and control area
F000h	0000h	16K	reserved ROM
	4000h	40K	base system ROM, ROM BASIC
	E000h	8K	ROM BIOS
low memory

If a TSR is created in assembly langauge, the programmer has exact control over the use of memory and can omit the heap area and place the initialization code at the end of the segment (where it can be released after initialization).

If a TSR is created in C, the small-memory model must be used. Because of the severe memory limitations, the programmer should not use C allocation functions (such as malloc and calloc), as these add to the heap. A small heap must be assigned because some C library routines (such as fprintf) allocate memory from the heap.

Variables required by MS-DOS interrupt handlers must be placed at the beginning of the code segment.