On Tue, 22 Jun 2010 23:16:00 +0100
"Rob Jarratt" <robert.jarratt at ntlworld.com> wrote:
> The machine came without a keyboard or mouse and I think I need at
> least a keyboard to get it to boot.
If no keyboard is connected the machine defaults to serial console on
the first serial port. (IIRC this is the DB25 one.) 9600 8n1. Before
investing money in a keyboard and mouse you should check if the machine
lives at all via the serial console.
--
tsch??,
Jochen
Homepage: http://www.unixag-kl.fh-kl.de/~jkunz/
Hi,
what exactly is a Mohawk Data Sciences (MDS) Series 21? There's almost
nothing on the net about that system apart from one small article in the
July 1978 issue of Computer. Is it worth saving?
Christian
I'm pondering making two types of P112 kits . First there is the complete
kit and then there would be a partial kit. The partial kit contains the
board, surface-mounts already mounted, and memory chips with boot rom
already burned in. How many of you would be interested in a partial kit
rather than a complete kit? I'm not sure of the prices yet.
--
David Griffith
dgriffi at cs.csubak.edu
A: Because it fouls the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?
Hi guys,
I've got a Laserjet III laser scanner module kicking around in my
junkbox, harvested from an utterly screwed LJ3. It has a fibre-optic
light pipe on one side, which connects to a photosensor on the
motherboard. Does anyone know what the frequency or period of the
photocell signal is?
That is to say, how long does it take for the scanner to make one
complete pass from "horizontal blank" to the right margin -- in other
words, the time from the leading edge of one photocell pulse to the next?
I'm toying with the idea of repurposing the scanner module for another
project (using a BluRay laser diode to print directly onto photographic
paper then process using a 3-bath B&W process), and I'd like to figure
out (in advance!) what the requirements will be placed on the paper
drive system (among other things!)
Thanks,
--
Phil.
philpem at philpem.me.uk
http://www.philpem.me.uk/
Jules,
A while ago you posted that you had the manual and discs for a Compaq
SLT/286. Do you by chance still have them? If so does it include the
Supplemental Programs disc?
Thanks
James
"Shoppa, Tim" <tshoppa at wmata.com> wrote:
> "Walter F.J. Mueller" <w.f.j.mueller at gsi.de> wrote:
>>> Johnny Billquist <bqt at softjar.se> wrote:
>>> > I wasn't aware that any prototypes ever were produced and came as
>>> > far as being functional. I thought it was just paper work that
>>> > had bee done.
>>>
>>> The 11/74 wasn't marketed, as pointed out in this thread, but a
>>> few systems were build by DEC. A picture of such 11/74 system
>>> was made available by Tim Shoppa, see
>>>
>>> http://www.trailing-edge.com/~shoppa/1174Xopen.jpg
>>>
>>> You'll nicely see the four CPUs.
>
>> Yes, I know of these systems. However, that is not an 11/74 on that
>> picture, but an 11/70mP. There is a difference...
>> As pointed out, the 11/70mP was marketed as an 11/74, but it's a
>> different CPU.
>
>> The easiest way to see that this is a picture of an 11/70mP is by
>> looking at the lower rotary switch, which only have four positions, and
>> not eight (which the 11/74 have). So no CIS on this machine.
>
>> The only 11/74 picture I've seen so far is the silk screen panel picture
>> posted a few days ago. Unfortunately I've already forgotten the name
>> (I'm lousy with names, sorry) of the person who posted it, and who also
>> worked on the 11/74 CIS microcode.
>
>> The machine on that picture is probably CASTOR:: by the way.
>
> The people who work with/maintain CASTOR:: call it a 11/74, FWIW.
Yes, I know.
I'll reply to this one last time, and then I'll give up.
Don North reported that he had been a part of the team that had written
the CIS microcode for the 11/74 CPU.
I commented that I thought the 11/74 CPU had only been a paper product.
Don North also pointed out that marketing "stole" the 11/74 moniker for
the 11/70mP system.
Now, throughout this discussion, we need some way of separating what we
are talking about. DEC internal project papers seems like a good start.
There we have the 11/70mP, which is a modified 11/70 with just the
addition of the ASRB cache bypass and memory interlock, as well as the
cache bypass bit in the PDR, and a cache bypass bit and flush control in
the cache control CSR.
The 11/74 is a total redesign of the 11/70 CPU, with the same
modifications as the 11/70mP, but also the addition of the CIS, removal
of one Massbus, and redesign of a whole bunch of CPU boards, including
removing one clock signal not used, and the addition of new clock
signals and control signals required by the CIS.
I'm only talking CPUs here, not systems.
Another way to name them would perhaps be:
KB11-B - Old 11/70 CPU with synch FPP.
KB11-C - New 11/70 CPU with asynch FPP.
KB11-CM - MP modified KB11-C
KB11-E(?) - The new 11/74 CPU with asynch FPP and CIS.
I seem to remember reading somewhere that the 11/74 CPU were to be
called KB11-E, but I also have this nagging feeling that KB11-E might
have been the 11/44, or possibly the 11/60.
Now, as I myself pointed out, RSX regards the 11/70mP as an 11/74, and
that is also what the CPU identification code in RSX calls it.
But if we call this an 11/74, what shall we call the 11/70 with CIS?
So, for the purpose of this thread, I decided to go with Don Norths
naming, and call the 11/70 modified for multiprocessor operations the
11/70mP. If you look at the picture on your site, Tim, you'll also
notice that the text on the front panel actually says something like
"PDP-11/74 MP". (Not sure about the /74, but you definitely see the "MP"
part. (http://www.trailing-edge.com/~shoppa/1174Xopen.jpg)
Now, compare that to Don Norths picture of the 11/74 front panel:
http://www.ak6dn.com/stuff/1174.jpg.
> They never used the term "11/70mP" in front of me for sure. I would occasionally elicit comments about multiprocessing on 73's or 93's but it always came back to "our 11/74 does it THIS WAY" because that was the working example.
I'm not disagreeing with you, Tim. I'm just trying to point out that we
have two different CPUs here, one of which I thought was never made, but
Don actually claims that it did exist, even if just as one prototype.
The system was called an 11/74 everywhere, but for the purpose of this
discussion, we need to make a distinction between the CPUs.
> I'm not saying that "11/70mP" is wrong, indeed it's used in some of the drawings and memos to describe what was commonly called the 11/74.
Yes.
> CIS was real important to some DECcies circa late 70's for some Cobol requirement but coming from the real-time side none of us ever cared. We'd just run across machines that had this unneeded option.
Indeed. And the 11/70 don't have it, nor does the 11/74 systems that
ever were used.
CASTOR:: was 4 CPUs, by the way, while PHEANX:: was only 2, if I
remember right.
Johnny
On JMon, 28 Jun 2010 22:15:57 +0100, Philip Pemberton <classiccmp at philpem.me.uk> wrote:
Having played with a the Canon II printer series scanners (the guts of both the Laserjet II and Apple Laserwriter II), some comments:
> Well, working backwards from DPI and print speed gives about 3MHz dot clock:
>
> 300DPI * 11 inches (paper height) * 3ppm = 9900 lines per minute
> (thus, the line rate is 9900Hz, or 9.9kHz)
> 9900lpm * 300 dots per line = 2.97e6
> (thus, the pixel rate is 2.97MHz)
Unless you are using the control board, the above calculation is moot: the scanner is a DC brushless motor - the speed is controlled by the input voltage. The control board closes a motor loop based on the feedback optical pulse and synchroniz(s)es the speed with the shift register clock. You can chose a clock rate to suit your system, build the motor control loop with a D/A, and set up logic to fire off at the right time based on the feedback optical pulse. If you are using the control board, all you have to do is feed the data in and the board will take care of the bit clocking. If you are generating the bit clock, you can determine your DPI. The II series uses a 6-sided mirror.
> Replacing the laser assembly might be "interesting", as will realigning
> the optics. My back-of-an-envelope calculations suggest I need a 0.085mm
> spot size to get to 300DPI:
>
> 300dpi = 300 dots per inch, or 1/300in per pixel
> 1/300 * 25.4mm/in = 0.0846667
>
> Focusing that will be.... "fun", especially with a 20mW blue diode
> laser... and I need to find a beam sensor that's sensitive to blue light.
The sensor on the board should work if you remove the red filter/attenuator on the input to the fibre optic cable. You might have to either increase the gain of the amp at the detector or place an attenuator in the optical chain. In any case, you should replace the red filter with a suitable pass filter to match your laser.
IIRC the laser is collimated to the desired spot size, i.e. the beam is parallel through the optical path - no focusing per se. However, going from red to blue will change the deflection characteristics of the optical path. You will probably see a narrower page at the same distance from the folding mirror and possibly some non-linearities. By changing the distance from the final mirror you should be able to control the page width. Non-linearities are a different matter.
>
> Seems like it should work... though designing a suitable
> constant-current controller with ~3MHz analog current modulation will be
> interesting. PWM would require ~768MHz modulation, so analog is the
> "easy way out", and beam power is roughly linear from the lasing
> threshold (30mA) up to 10mW (~40mA). Hmmm.
As mentioned above, you will have to control the motor voltage to sync with the bit oscillator to achieve the DPI. Also note that most laser diodes have a photodiode as part of the assembly and power is also in a control loop.
[...]
> So am I right in thinking it has some form of PLL to generate the pixel
> clock from the beam-detect (or motor tacho?) pulses?
Actually, you probably want to fix the bit rate (crystal oscillator) and control the motor speed so that you get n bit counts between laser pulses. It should be fairly easy to control to +/- 1 bit. Note that the number of bits will be greater than the dots you wish to generate in order to take care of margins.
>
> That's along the lines of what I was going to do... lock a fairly
> slow-loop PLL off the either the beam detect or the tacho (haven't
> decided which), then use the pulses from that to drive the clock input
> for the data shifter.
>
> It's like the CX-VDO all over again.... :)
Different problem...
>
> --
> Phil.
> classiccmp at philpem.me.uk
> http://www.philpem.me.uk/
I used two scanners a few year ago to make a far IR scanner. The first was a modified mirror wheel which slow scanned the vertical and the second was the horizontal scan. The optical output was fed to pyroelectric detector found in a motion detector with modified electronics. Fun toys.
CRC
