YES! The monster booting again! :-)
Thus after checking the condition of the capacitors and the rectifying
diodes by interchanging the 5v sources under the advice of Curious Marc,
a finally swapped Q12 and Q13, find the dead one, replace Q13. Following
the advice of Christian I raised both regulated + 5V by taking into
account the resistance of the circuit. It was a good advice because in
full load, it was missing something like 0.3V.
Finally I was for sure with a machine that would running but not booting.
As I suspected a problem with the OS installed in the core memory and on
the Diablo 44 I tried in vain to reinstall this OS (Didos) from tape
drive, unsuccessfully. To spice things up ,the machine fall in
protection because of an overheating in the power supply G1.
I open for the 20th time these two PSU, to find that the fan of G1 is
dead, I tried to repair it but the coil is downright grilled. It's good
news. I find another fan, I do not have a 115VAC in stock , I solder new
wires to feed 220VAC to the "new" fan. Problem solved !
http://www.zeltrax.com/classiccmp_forum/second_boot/00a.jpg
http://www.zeltrax.com/classiccmp_forum/second_boot/00b.jpg
And now let's go to find the problem on the Pertec tape drive side,
engine control works, it's like if it reading/receive nothing, I
cleaning the read head again, connectors (read, write, control), I
linger on the front buttons and bingo! The lamp of the switch 500/800
BPI stays lit regardless of the real state, thus I was trying to read
800 bpi tape under 500 bpi modewithout knowing. Small but vicious failure.
After that I was able to install from the master tape a new version of
this OS, YES ! I reformatted the Diablo disk, I made read tests, writing
with various devices, all seems OK!!
I'm happy, this machine comes back from afar ;-)
I have five Entrex terminals but I will already take care of the one
currently active, it must be cleaned from top to bottom. The plastic of
the hull is yellowed by the years, I think I will not have fun to do
retrobright, I will squarely repaint it. The keyboard works well but
some touch contacts are a bit recalcitrant. About the printer there is
work, I will rather concentrate about the Operating System because here,
besides the small happening aesthetic that I allow myself to do now, it
is imperative that I find an Operating System, a real OS and even several.
The stuff currently installed is very basic, extremely closed, hyper
limited, for my part this OS does not even deserve the name of OS, it is
a simple data acquisition software with some abstruse utilities, DIDOS
was Developed by Nixdorf for its "own" model 620, a D-116 (17 slots)
made up of Digital Computer Control (itself being a clone of Nova 1200).
As I describe in other posts, the CPU seems to have been upgraded since
it dates from 1978 while some maintenance control stickers date from
1976, another on a multiplexing card for terminals Entrex displays 1974.
I'm going on the idea of finding RDOS for the 16-bit Nova line, but
maybe I could install a newer OS (eg AOS for the 16-bit Eclipse)? I also
read many pages on which it was also a question of DG-DOS, RTOS, NIROS
.... know you others?
In any case one thing is sure: I searched for hours and I did not find
anything to make a new op-sys tape to install something else instead of
my pathetic Didos. The only downloadable data I found, some RDOS sources
for SIMH which emulates the DG NOVA. Do any of you know where I might
find these precious data?
Of course I also look for a maximum of programs to install on the monster.
For info I have a VAX 4000-605A with a TU81 + (currently disconnected)
but which would allow me to write a tape with data transiting thru my
home network.
Otherwise I also have a Shugart (KENNEDY) 9612 which can write in 800,
1600, 3200 or 6250 bpi, this tape drive is equipped with a SCSI interface.
<https://computerarchive.org/files/comp/hardware/Shugart%20Kennedy%209-track%209610%20tape%20drives.pdf>https://computerarchive.org/files/comp/hardware/Shugart%20Kennedy%209-track%209610%20tape%20drives.pdf
I have not analyzed if I can connect it directly to a good old Adaptec
controller inside a PC, nor with which program I could exploit it.
Besides if you have information about this they are welcome!
And finally, while waiting for the video, here some pictures of the
machine in operation ;-)
<http://www.zeltrax.com/classiccmp_forum/second_boot/01.jpg>http://www.zeltrax.com/classiccmp_forum/second_boot/01.jpg
http://www.zeltrax.com/classiccmp_forum/second_boot/02.jpg
http://www.zeltrax.com/classiccmp_forum/second_boot/03.jpg
http://www.zeltrax.com/classiccmp_forum/second_boot/04.jpg
Dominique
PS: AJ, some pics of the Entrex terminal for you above ;-)
