Q: No partition possible for reinstallation of El Capitan

OK thanks. just to check, i have gdisk 32 BITS for my system, is that ok or i still use 64?

my window is not showing like yours?

GPT fdisk (gdisk) version 1.0.1

Type device filename, or press <Enter> to exit: GDISK32.EXE
NOTE: Write test failed with error number 6. It will be impossible to save
changes to this disk's partition table!

Partition table scan:
  MBR: not present
  BSD: not present
  APM: not present
  GPT: not present

Creating new GPT entries.
************************************************************************
Most versions of Windows cannot boot from a GPT disk except on a UEFI-based
computer, and most varieties prior to Vista cannot read GPT disks. Therefore,
you should exit now unless you understand the implications of converting MBR
to GPT or creating a new GPT disk layout!
************************************************************************

Are you SURE you want to continue? (Y/N): Y

Command (? for help): GDISK32.exe 0
b       back up GPT data to a file
c       change a partition's name
d       delete a partition
i       show detailed information on a partition
l       list known partition types
n       add a new partition
o       create a new empty GUID partition table (GPT)
p       print the partition table
q       quit without saving changes
r       recovery and transformation options (experts only)
s       sort partitions
t       change a partition's type code
v       verify disk
w       write table to disk and exit
x       extra functionality (experts only)
?       print this menu

Command (? for help):

Hello again,

I managed to follow procedure in cmd window. Step by step including "d" + changes to partition. I then pressed "Y" to confirm and the computer shut down !

As you predicted, the black screen shows "no bootable device -- insert boot disk and press any key"

I suppose I should have waited before the "Y" command, sorry ! I tried following instructions very carefully.

Ok thanks. I have done that and tried to reboot. Not sure the NVRAM worked properly as the mac starts up to HD mac disk without booting. I don't see any options to boot into windows 7.

Last login: Sat Sep  3 14:53:40 on console

pc54:~ stuarthallett$ sudo gpt -vv -r show /dev/disk0

Password:

gpt show: /dev/disk0: mediasize=1000204886016; sectorsize=512; blocks=1953525168

gpt show: /dev/disk0: PMBR at sector 0

gpt show: /dev/disk0: Pri GPT at sector 1

gpt show: /dev/disk0: Sec GPT at sector 1953525167

       start        size  index  contents

           0           1         PMBR

           1           1         Pri GPT header

           2          32         Pri GPT table

          34           6        

          40      409600      1  GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B

      409640  1315481784      2  GPT part - 48465300-0000-11AA-AA11-00306543ECAC

  1315891424     1269536      3  GPT part - 426F6F74-0000-11AA-AA11-00306543ECAC

  1317160960      204800      4  GPT part - EBD0A0A2-B9E5-4433-87C0-68B6B72699C7

  1317365760     1269536        

  1318635296   634889839      5  GPT part - EBD0A0A2-B9E5-4433-87C0-68B6B72699C7

  1953525135          32         Sec GPT table

  1953525167           1         Sec GPT header

pc54:~ stuarthallett$ sudo fdisk /dev/disk0

Disk: /dev/disk0 geometry: 121601/255/63 [1953525168 sectors]

Signature: 0xAA55

         Starting       Ending

#: id  cyl  hd sec -  cyl  hd sec [     start -       size]

------------------------------------------------------------------------

1: EE 1023 254  63 - 1023 254  63 [         1 - 1953525167] <Unknown ID>

2: 00    0   0   0 -    0   0   0 [         0 -          0] unused     

3: 00    0   0   0 -    0   0   0 [         0 -          0] unused     

4: 00    0   0   0 -    0   0   0 [         0 -          0] unused     

pc54:~ stuarthallett$

Booted to os x utilites console. Used terminal from menu:

-bash-3.2# csrutil status

System Integrity Protection status: enabled.

-bash-3.2# csrutil disable

Successfully disabled System Integrity Protection. Please restart the machine for the changes to take effect.

-bash-3.2# csrutil status

System Integrity Protection status: enabled.

-bash-3.2#

back on track maybe

terminal :

Last login: Sat Sep  3 16:25:20 on console

pc54:~ stuarthallett$ csrutil status

System Integrity Protection status: disabled.

pc54:~ stuarthallett$