I just finished installing Windows 95 4.00.950 B from floppies and it runs perfectly... The only modifcations to the CT486 machine i have done are 8MB of RAM and a CD-ROM drive... this is my command line
mame ct486 -hard1 hd\HD504MB_pruebas.chd -board3:ide:ide:1 cdrom -ramsize 8M
the HD was created with chdman, using the following configuration: 1024 Cylinders, 16 heads, 63 sectors/track, 512 byte sectors
The problems were the RAM size and the disk configuration: I've reduced the -ramsize option from 64M to 32M (I've got an old real 486DX2 PC with 32 Mb RAM) and set the disk configuration you stated: 1024 cyl + 16 h + 63 sect and could complete my installation.
To allow Win95 (my version is just "4.00.950") to boot without freezing I've had to remove the "-isa ne2000" as well; at present I get an error message but I can reach the Windows desktop. I'll check later if the NIC works.
Unfortunately I have to set the disk configuration every time I start the machine, since the BIOS shows a "cmos size mismatch" at boot and states 4161 cylinders instead of 1024, maybe because I haven't reinstalled everything from scratch.
Last note: creating a 500 Mb hard disk via chdman its output is 2048 cyl, 16 h, 32 sect. Such data didn't work to correct my installation, maybe they can get saved reinstalling everything.
Many thanks again, bye!