EMM200 Patch for 4MB HP200LX

1. Applying patch.
1. rename EMM200.EXE to EMM200.BIN
2. under the DOS session apply patch
• debug < emm200_4m.pat
3. rename EMM200.BIN to EMM200.EXE
2. Or you can download the pre-patched binary
3. Installing
1. You need a special configuration program or hassle with debug command to get work the patched version EMM200. Sorry I have no time to make the program, please wait who wants it.

• This patch needs reconfigure of your RAM drive(C:), all data on the C: drive will be lost during the instalation of EMS paging area. Be sure to back your C: drive up.
• Who do not want to wait until the configuration program available, make EMS paging area as followings:
• Make extended BIOS area writable
  

  o22,87
  o23,a0
  

• set 2nd permanent sector memory start to your EMS paging file size(unit 1KB) 9f00:0a-0b
  If you want 256KB of paging area, you can set the value as followings:

  e 9f00:0a 0
  e 9f00:0b 1
  

• subtract the same amount from the memory length field 9f00:0c-0d
  If you have the 4MB model as same as mine, then these area may be "00 08" . For the 256KB of paging area, you can set the value as followings:

  e 9f00:0c 0
  e 9f00:0d 07
  

• recalculate checksum and set it to 9f00:27-28(you may not need to set because above step add XX to the table and subtract XX from the table)
• make extended BIOS area readonly
  

  o22,87
  o23,9f
  

• issue initialize RAM Disk BIOS call with debug command

a100
mov ax,ff01
mov dl,1
mov bx,0
mov cx,0
int 13
int 3

g=100

• reset 200LX with ctl-alt-delete
• check your RAM drive with chkdsk command.
• transfer the patched emm200.exe from somewhere
• make your config.sys include following line
• DEVICE=C:\emm200.exe
• restart 200LX
• check with MEM command, whether it reports the availability of EMS memory.

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