Dietmar

@roytam1 Have you tested with the modded WINNT32A.DLL and WINNT32U.DLL, if the hack in ntoskrnl.exe against Bug Check 0x5D UNSUPPORTED_PROCESSOR is not necessary any longer Dietmar

@roytam1 With my XP TXTSETUP runs ok. But then, after first reboot, compi hangs after about 4 min. Sometimes hanging after about 4 min and sometimes during detect of devices (37min to wait is shown). Are WINNT32A.DLL and WINNT32U.DLL on the german CD the same as on English ones? Please tell me the crack or send me the already modded files Dietmar

Yessssaaa, it installs XP SP3 on my AMD 486 133MHZ cpu !!!!!!!!!!!!!!!!!!!!!!!!! Even I do not get any Bsod before, I did exact the same extras as you: Extra setupldr.bin patch 75 to EB in 0x23513 (strange, because it has CPUID), and replacing NTKRNLMP.EXE with our hacked NTOSKRNL.EXE, niccccccccccccccccccccceee.. And I also delete logagent.exe and wmnetmgr.dll from the XP SP3 install CD, because those 2 are the only files left, with CMPXCHG8b opcode in it Dietmar

@roytam1 I am just testing on Shuttle Hot 433 board with AMD 133 MHZ486 cpu AMD AM5x86-P75 Dietmar EDIT: On real 486 compi, the same reboot happens before the F8 appears. Is there something other, that you change on my "Source" CD for setup of german XP SP3 with all those modded files?

@roytam1 I replace the second ntdll.dll with my modded one but get the same reboot just at the end of the Setup process, before you have to hit F8. Please, can you tell me, what simulator you use for the AMD 486 cpu. And is there a possibility, even in this very first Setup of XP to let Windbg watch it, may be via a crash debug log Dietmar

@roytam1 With this changes, can you install XP SP3 now on a 486 cpu Dietmar

@roytam1 The ntdll.dll is patched. So I dont know, where this Bsod happens Dietmar EDIT: Ah, I see, there is a second ntdll.dll on the xp.iso, crazy;))..

@roytam1 Please describe more exact this Bsod. I test all my modded files a lot and now no kind of such a Bsod happens to me. Does it happen during Setup of XP, my modded setupldr.exe and setupldr.bin together with my modded ntdll.dll Dietmar

@roytam1 Until now,all the 486 cpu's are treated as the Pentium Overdrive 486 Podp5v83.This makes the aktual Xp slow on the Amd processors.For to speed them up a lot,we need to build a real xp486.iso ,where the correct cpu is listened via Cpuid.For me this is hard work,because no Windbg during very first steps of Setup.May be,in this situation an emulation can help a lot,when this emulation can build a real amd486 cpu Dietmar Edit: A elegant solution for this would be,to use the Source for Xp Sp1, adding all 486 cpu's there and just compile a new setupldr.exe and *.bin

After a new, full install of XP SP3 on a 486 cpu, I get a boottime from less than 2 min. Now XP uses full 256MB ram, cached with 1024 Cache memory. The load of the cpu goes down to 35%, when doing nothing. With this XP you can work, oh..soso much fun Dietmar

@genieautravail ChatGPT is blind as much as possible in coding. Nearly nothing is correct, even most easy errors. BUT: You can use ChatGPT for to get new ideas. The hard way to make them come true, is ALWAYS on you Dietmar

Here is the source for the 486 fun above Dietmar https://ufile.io/i3j8idk7

@Cixert It is not difficult, to change from Standard PC to Acpi Multiprocessor via a Bios, that supports ACPI for XP. Your case is very different from this: After Bios update, your DSDT and SSDT tables have changed. Now, XP CANT boot any longer with acpi via them. From my experiments, mostly this goes to an "new" incompatible Graphik Mode. Your problem can be easy solved with the acpi patcher at boot time from @Mov AX, 0xDEAD. There you give them via modded ntldr always your old acpi tables, that you have fetched for example via RWEverthing in binary form. After this, your compi works like before, tricking out the new Bios Dietmar PS: Another way is just to go back to your old Bios. But this can be impossible, even with EEprom Bios chip writer.

@Cixert Yes, I try also the 486-step3 hal.dll. Same reboot until now. @ProgramHacker With 256 MB cached ram and 160 MHZ, you can work with XP SP3 on a 486 cpu. It is still slow but enough for easy tasks. For me it is just fun as much as possible, to understand XP much better and how to speed it up Dietmar

I think, that the reboot of the 486 compi during Setup happens, because CPUID gives values in all those registers, which tell Setup, that it is an unsupported cpu. The same happened when using a ready IDE install and can be overcome only with the nice hack from @roytam1 against Bsod 0x0000005D, Bug Check UNSUPPORTED_PROCESSOR. May be a working solution would be, to fake the 486 cpu with the CPUID settings of the Intel Overdrive 486 cpu podp5v83. But this needs to be checked careful. Anyway I get stable XP SP3 on 2 different Amd 486 cpu's, 100 MHZ and 133 MHZ. With updating the Cache to 1024 KB, may be, that XP uses all the memory and then it will be much faster Dietmar

It workkkkkkkkkkkkkkkkkkkkkkkkkkkkssssssssssssssssssssssss Just now I am installing XP SP3 via CD on an AMD 486 100MHZ cpu Dietmar EDIT: But 486 compi reboots at the place, Windows is starting, when the harddisk should be seen.. EDIT2: Rom also was not build in one day. So, for today it is a nice result to overcome the CMPXCHG8B check in XP. Here are all my files until now for 486 XP SP3 boot and install https://ufile.io/7bgj5rv1

Problem is, that we have only 6 byte for all. May be this bts edx, 8 ; Set the 9th bit in EDX and update the zero flag == 0f ba ea 08 test edx, edx ; Test the value of EDX against itself to clear the zero flag == 85 d2 So, always the 9th bit in EDX will be set, no matter if it was set already or not. And the test edx, edx makes sure, that the zeroflag is cleared. No other value in EAX, EBX, ECX, EDX is disturbed from this hack waaoh Dietmar

May be, that the check for the 9th bit in EDX for the present of CMPXCHG8B on a cpu can be faked via this Original test edx, 100h == F7 C2 00 01 00 00 replaced with or edx, 100h == 81 CA 00 01 00 00 It does not change any other in EDX, it just sets this 9th bit for CMPXCHG8B in EDX and the ZeroFlag behaves after this operation in both identically Dietmar

@user57 CPUID is really a lot of stuff, see at this https://www.sandpile.org/x86/cpuid.htm Yepp, the aim can be, to set all values correct for the 486 AMD 133 MHZ cpu, Am5x86, and with a fake bit for the CMPXCHG8B. This 486 cpu is cheap, has 16kB cache and can be overclocked to 160..(200) MHZ Dietmar PS: I get 486 cpu's to run stable XP SP3: AMD 100 MHZ and AMD 133 MHZ. Only install of XP SP3 for this cpu's is not so easy.

@roytam1 No, in setupldr.exe is no more check for this. BUT: I find the same check in setupldr.bin Dietmar seg000:000213A1 loc_213A1: ; CODE XREF: sub_211FF+195j seg000:000213A1 call sub_24F4C seg000:000213A6 call sub_2995C seg000:000213AB test al, al seg000:000213AD jz short loc_213BA seg000:000213AF push 236Dh seg000:000213B4 call sub_25596 seg000:000213B9 pop ecx seg000:000213BA seg000:000213BA loc_213BA: ; CODE XREF: sub_211FF+1AEj seg000:000213BA call sub_299A0 seg000:000213BF test ah, 1 seg000:000213C2 jnz short loc_213CF seg000:000213C4 push 238Ch seg000:000213C9 call sub_25596 seg000:000213CE pop ecx

@roytam1 I mean, at which place for CPUID or CMPXCHG8B this check is done Dietmar

@roytam1 Do you have an idea, from where that crazy message about CPUID and CMPXCHG8B can come? I look via Ida Pro and the Debug version of setupldr.exe but do not find another place for that check. I also look at the Source files for XP SP1. But also there, I can find only this single place from above Dietmar

May be this is a more elegant way, because it sets the last bit in ah always to 1, no matter what has been there before and does not change any other bit in ah and gives the same result as the test, if the last bit in ah is 1 Dietmar .text:0031F3CB call sub_315CDC .text:0031F3D0 or ah, 1 .text:0031F3D3 jnz short loc_31F3E0 .text:0031F3D5 ; --------------------------------------------------------------------------- .text:0031F3D5 push 238Ch .text:0031F3DA call sub_323C94 .text:0031F3DF pop ecx

@Mov AX, 0xDEAD I try to hack the question about CPUID and CMPXCHG8B in setupldr.exe from XP SP3 on the xp.iso. I search via the debug version of this setupldr.exe, but changes I do in the free version of setupldr.exe. Still I get this crazy message about no CPUID CMPXCHG8B on this 486 compi and I have no idea, from where it comes. This I have changed in setupldr.exe. Thanks for help Dietmar .text:0031D48F loc_31D48F: ; CODE XREF: SlInit(x,x,x)+195j .text:0031D48F call _SlInitDisplay@0 ; SlInitDisplay() .text:0031D494 call _BlIs386@0 ; BlIs386() .text:0031D499 test al, al .text:0031D49B jz short loc_31D4A8 .text:0031D49D push 236Dh .text:0031D4A2 call _SlFatalError .text:0031D4A7 pop ecx .text:0031D4A8 .text:0031D4A8 loc_31D4A8: ; CODE XREF: SlInit(x,x,x)+1AEj .text:0031D4A8 call _BlGetFeatureBits@0 ; BlGetFeatureBits() .text:0031D4AD test ah, 1 .text:0031D4B0 jnz short loc_31D4BD .text:0031D4B2 push 238Ch .text:0031D4B7 call _SlFatalError .text:0031D4BC pop ecx ==> .text:0031D48F loc_31D48F: ; CODE XREF: SlInit(x,x,x)+195j .text:0031D48F call _SlInitDisplay@0 ; SlInitDisplay() .text:0031D494 call _BlIs386@0 ; BlIs386() .text:0031D499 test al, al .text:0031D49B jmp short loc_31D4A8 .text:0031D49D push 236Dh .text:0031D4A2 call _SlFatalError .text:0031D4A7 pop ecx .text:0031D4A8 .text:0031D4A8 loc_31D4A8: ; CODE XREF: SlInit(x,x,x)+1AEj .text:0031D4A8 call _BlGetFeatureBits@0 ; BlGetFeatureBits() .text:0031D4AD test ah, 1 .text:0031D4B0 jmp short loc_31D4BD .text:0031D4B2 push 238Ch .text:0031D4B7 call _SlFatalError .text:0031D4BC pop ecx

For to overcome my ultraslow IDE HD with 7 (!) MByte/s I bought this adapter https://www.amazon.de/gp/product/B00EOJNGC2?ref=ppx_pt2_dt_b_prod_image So, from tomorrow starts fun, because this adapter works also with SSD and 6 Gbit/s Dietmar