> From: Ben Sinclair
> If I setup the BDV11 to control the LTC interrupt, should I have W4 in
> or out?
If you have W4 in, you can do whatever you want on the BDV11, with the front
panel LTC ('Aux') switch, etc, and it won't make a difference - the machine
will not do LTC interrupts, no way, no how! :-)
If W4 is out, _and_ the LTC switch on the front panel is on, _and_ the BDV11
is set up to control the LTC, then the machine will boot with the LTC off,
and the LTC can be turned on by the software (by storing a '0100' in 177546).
> I'm currently only running with the CPU, memory, and serial boards
> installed.
Oh, one other thing to pay attention to: not all DEC backplanes have
termination QBUS pull-up resistors. The H9270 and H9373 (normal equippage in
the BA-11M and BA-11N boxes, respectively), for instance, do not. Those
machines need something at the end of the bus to provide the
termination/pull-up - such as a BDV11 or an REV11.
And then we get to 18 and 22 bit busses... :-)
Noel
Hello Adrian,
I can't come to uk to take up the stuff, but still I'm very interested to
unibus (possibly qbus) boards.
Do you think you could add some to the box of the SDI disks you have there
for me, when possible?
Thanks in advance
Andrea
> From: Ben Sinclair
> I did not have a jumper on W4, so I added one
Err, adding jumper W4 _disables_ the LTC interrupt; see pg. 324-325 of the
"Microcomputers and Memories Handbook (1982)". (Since you were apparently
seeing LTC interrupts before, it makes sense that the prior state of the
board had them enabled...) If you don't have that book, worth picking one up
on eBay - full of all sorts of useful info.
> The test I can't run .. is the JKDBDO CPU test. When I try to run this
> one it doesn't print anything and drops me to ODT at 037526.
Hmm. Probably need listings, or something, to figure out what it's unhappy
about. The only documentation I could find online is the "PDP-11 Diagnostic
Handbook", and various copies of the content there, and it's not very
detailed. (BTW, it's probably 'JKDBD0', not "JKDBDO".)
> The BDV11 manual says they are controlled through a register via
> software, so maybe I'm just not running anything that sets them.
That would be my guess too.
> The only boot rom I have on the BDV11 is a TU58 boot loader, so if it's
> up to some other boot rom to set that LED register
More likely the system software, not the ROM.
Noel
Hello there,
we have a Silent 709 with external modem, connected through a db25M on
the machine. is it vey different from a 703 with just a RS232 connection?
is this convertible to RS232?
--
Met vriendelijke Groet,
Simon Claessen
drukknop.nl
A contemporary band recently released a CD without a reflective layer.
My son asked me about ways it might be read.
It looks completely clear but when tilted in the light you can see the
rainbow of recorded material. I believe it's a data CD, not audio,
as statements from the band hint it contains the MP3s of their
previous four albums.
(Why did the band do this? They said they were making an artistic
statement about the nature of and longevity of CDs, and as a puzzle
to their fans. The other half of the package was on a second CD in
an uncommon format known as "Mini-Max", where it is an ordinary-sized
CD but only the center 3" is silvered, giving it a distinctive look.)
I asked a friend who was an engineer at a 3M pressing plant in 1986-88.
He said that early CD-ROM drives could read a CD that didn't have a
reflective layer. He thought these drives had some of the first
Phillips and Sony mechanisms. He said they read discs like this
"all the time" in the production process. He also thought there were
a few "novelty" cealer discs produced this way in those early days.
He thought that by today's standards, these first-gen readers had lasers
that were overpowered and the gain circuitry more sensitive, so they
were able to read the un-aluminumized pits in the pressed polycarbonate.
I believe I first acquired a CD-ROM drive in 1988 or so. I may even
still have it, but I've yet to hunt for it in my storage. I don't
remember the brand of its internals.
On eBay I see old Phillips CD reading mechanisms selling for astounding
prices of more than $500, as they're used by equally astoundingly-priced
($3,000-5,000) high-end CD players such as the Studer brand. Bits is
bits, you'd think, but as usual, not for the high-end audio enthusiast.
http://www.thevintageknob.org/THEVAULT1/D730/D730.html
The same mechanisms were used in the first CD-ROm readers for PCs
such as the Phillips CM100.
I believe this CD has its top-coat of acrylic / lacquer. I think
that adding a reflective layer at this point (such a shiny paint) wouldn't
affect the readability of the pits (and that spray-paint would probably
melt the lacquer.) As I understand it, the depth of the pits are
about a fifth of the wavelength of the light used to read them,
so the detector sees a phase shift.
Does anyone remember if first-gen CD drives had such super-powers?
Does anyone remember any clear pressed CDs? Any advice on how this
clear CD might be read?
- John
> From: Ben Sinclair
> I wasn't clear though on the discussion about the line clock... If my
> machine is having problems with the line clock, would I need to do
> anything to the aux switch, other than leave it in a certain position?
Well, I wouldn't call it a 'problem'. The thing is that the 11/03 and 11/23
were, unlike all other PDP-11s, designed with a line clock which _the software
could not enable/disable_. [*] The only way to turn the LTC on/off on those
machines is with that front-panel switch. When running software which _does
not_ handle line clock interrupts, turning the LTC on will blow the software
away - it will get an un-handled interrupt. (As happened to you.)
So if you're running code which does not use/handle the LTC (like XXDP,
apparently), turn it off. If you're running something that does want/need it,
turn it on. (And some software may require that it be _off_ while booting, and
turned _on_ once the system has started - Unix V6 falls into this category.)
* Two caveats. First, the 11/23-PLUS _does_ have software control over the
LTC; there's an LTC register on that board; it's only the dual-height 11/23
which does not. Second, the BDV11 card has this really elegant kludge that
basically adds an LTC register to a 11/03 or an 11/23, so on an 11/03 or 11/23
with a BDV11, you can leave the LTC switch on all the time, and the software
can enable line clock interrupts if it wants them.
Noel
> From: Noel Chiappa
> There's documentation somewhere (don't recall off the top of my head
> ..) about how to configure the Aux switch.
Remembered where I saw it: in the "PDP-11/23B Mounting Box User's Guide"
(EK-23BMB-UG-001), available here:
http://www.computer.museum.uq.edu.au/pdf/EK-23BMB-UG-001%20PDP-11-23B%20Mou…'s%20Guide.pdf
among many other places, on pp. 2-3 and 2-4. (This manual talks about the
BA11-S, but the front panel configuration is the same for other boxes - my
BA11-N has the exact same hardware on the front panel.)
Noel
Shortly I'll be building yet another HP2000 TSB machine, so I'm looking for
either of the following:
HP 12920B Asynchronous Multiplexer :
12920-60001 Upper Select Code Data Board
12920-60002 Lower Select Code Data Board
12922-60001 Control Board
Or
HP 12920A Asynchronous Multiplexer:
12921-60001 Upper Select Code Data Board
12921-60002 Lower Select Code Data Board
12922-60001 Control Board
Generous bounty and/or trades available for either of the above. Even single
boards of any of the above would be a big help.
Best,
J
> From: Yvan Janssens
> TNMOC in Bletchley Park [1]
> ...
> [1]: http://www.tnmoc.org/
Wow! What a great site! Thanks for the pointer. Y'all should go check it out
- they are building an EDSAC replica, and the have the original Harwell
Dekatron (aka WITCH) - the world's oldest operational computer - designed
1949, first operated 1951.
Noel
Curious if anyone might remember this.
On the HP2K TSB system I used in high school, there was a system library
program to assist with what we then called "spot plotting". This is what
allowed you to position the cursor anywhere on the screen (given a terminal
specific library of control codes for each terminal).
All I can remember was that the system library program was called something
like $PLOT or $ZPLOT or something similar. It was something to the effect of
a different string with the control codes for each terminal, and the
substring positions matched up with the row/column you wanted to go to. So
printing A$(3,1);A$(8,1) or similar positioned the cursor at row 3 column 8.
I'm sure this description isn't completely correct but it was something
similar to that.
I've looked through the HP Contributed library and while I can find a number
of programs named similar to PLOT, none of them seem to provide this
functionality. Perhaps it was site specific, but I'm wondering if anyone
remembers anything like this and can shed light on it? I think it was a
program stub that you "APP-" to your program, not sure.
Best,
J
