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RBBS in a Box Volume 1 #2
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RBBS_vol1_no2.iso
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011p
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environ.pat
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1985-03-23
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2KB
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45 lines
-------------
-ENVIRON.PAT-
-------------
The following is a patch for COMMAND.COM (IBM-PC) to allow
for a larger environment area. Currently, only 223 bytes total
are allowed for environment string storage, with all data over
22│á byte≤ truncated«á ┴ large≥ environmen⌠ areß caε bσá quitσ ì
usefu∞á fo≥ passinτ variable≤ betweeε differen⌠ program≤á anΣá iε ì
BATCH commands.
Usσá thσ followinτ patcΦ t∩ increasσ thσ sizσ oµ thi≤ datß area:
For DOS 2.0:
1) DEBUG COMMAND.COM (load COMMAND.COM into debugger)
2) S 100 4600 BB 0A 00 B4 48 CD 21 (search for allocation call)
3) Replace the 0A with the new area size factor (in paragraphs).
The string searched for in step 2 is a call to allocate space for the
environment area:
BB 0A 00 MOV BX,0AH ; area size factor=10 decimal
B4 48 MOV AH,48 ; allocation function number
CD 21 INT 21 ; perform allocation call
Thσ areß sizσ facto≥ i≤ calculateΣ a≤á ((AF+4)*16)-1¼á witΦ ì
areßá facto≥á AF«á Thσá defaul⌠ valuσ oµ 1░á decima∞á yield≤á aε ì
environmen⌠á areßá oµ 22│ bytes¼á increasinτ thσ valuσá t∩á 2░ ì
decima∞á (14H⌐á wil∞ yielΣ aε areß oµ 38┤ bytes╗á increasinτá thσ ì
valuσ t∩ 3░ decima∞ (1EH⌐ wil∞ yielΣ 54┤ bytes«
For DO╙ 2.1░ thσ areß facto≥ bytσ i≤ pluggeΣ iε a⌠ locatioε ECF.
For DO╙ 3.0░ thσ areß facto≥ bytσ i≤ pluggeΣ iε a⌠ locatioε F2C.