Why would this test program use 900K+ memory?

[CCurl]

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; TEST program
; ---------------------------------------------------------------------------------------------------------
.686P
.model flat, stdcall
.stack 4096

; ---------------------------------------------------------------------------------------------------------
ExitProcess PROTO,
dwExitCode:DWORD

GetStdHandle PROTO,
dwWhich:DWORD

ReadConsole EQU <ReadConsoleA>

ReadConsole PROTO,
hConsoleInput:DWORD,              ; input handle
lpBuffer:PTR BYTE,                ; pointer to buffer
nNumberOfBytesToRead:DWORD,    ; number of chars to read
lpNumberOfCharsRead:PTR DWORD,  ; ptr to number of bytes read
lpReserved:DWORD                ; (not used)

; ---------------------------------------------------------------------------------------------------------
; Constants

STD_INPUT_HANDLE EQU -10

; ---------------------------------------------------------------------------------------------------------
.data

hStdIn DWORD 0
buf byte 0 dup (100)
num dword 0

; ---------------------------------------------------------------------------------------------------------
.code

main proc

invoke GetStdHandle, STD_INPUT_HANDLE
mov hStdIn, eax

mov edx, offset buf
INVOKE ReadConsole, hStdIn, edx, 100, ADDR num, 0

invoke ExitProcess,0
ret

main endp
end main

; ---------------------------------------------------------------------------------------------------------


[CCurl]

Is it because it links in kernel32.dll?

[dedndave]

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buf byte 0 dup (100)

try this, you can place it in the .DATA? section

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buf byte 260 dup (?)

the ReadConsole function likes to have 256 bytes, plus a couple extra for termination
we make it 260 so it's evenly divisable by 4

as for the memory usage, i doubt it uses 900 K
however, CMD.EXE might use quite a bit   

[dedndave]

oh - and don't define a stack
use this....

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        .686p
        .MODEL  Flat,StdCall
        OPTION  CaseMap:None

[jj2007]

Windows is generous: by default, all programs get about one megabyte.

For further reading, Mark Russinovich has a nice series starting with Pushing the Limits of Windows: Physical Memory

[Zen]

...Oh, yes,...and speaking of  Mark Russinovich, he has an excellent FREE utility: Process Explorer v16.05, TechNet

[qWord]

Is it because it links in kernel32.dll?

yes, among others. However that are unavoidable costs, because you can't create any useful program without these APIs.