Date: Sun, 11 Mar 2007 09:47:28 -0700
From: "Chuck Guzis" <cclist at sydex.com>
Subject: Re: baud modifier
>Terminal switchers that accommodate baud rate differences are still
>made:
>http://www.networktechinc.com/srvsw-term.html#
>Cheers,
>Chuck
-------------------------------------------
I've still got a few NC-16 Net Commanders that are similar to
those units in case anyone's interested. Same as the one Tony
mentioned, but single board, RS-232 only, 110 to 19200 baud.
mike
On 3/11/07, Zane H. Healy <healyzh at aracnet.com> wrote:
> Cool! is this the Caddy 6x drive? I collect the Plextor caddy drives
> whenever I can find them. I think I'm up to 3 6x drives, and 1 8x
> (which is the drive in my PDP-11).
The Plextor PX-6XCS is indeed an external SCSI CD-ROM Caddy 6x drive.
I'll keep my eye out for more of these if find them cheap locally. I
just checked the Plextor manual for the PX-32CSi/e (Caddy) and
PX-32TSi/e (Tray) series and they still have 512-byte Block jumpers.
Those models don't seem to be too hard to find locally. There are
some on Craigslist locally right now.
> That is correct. Do you have the Hobbyist Licenses yet? You'll
> probably want to start working on that first.
>
> Zane
I don't have the Hobbyist Licenses yet. I'll take care of that after
making sure the MicroVAX II/III hardware seems to be working.
-Glen
If someone can provide me with an environment that will host mono and
its asp.net clone, then I can build some web site tools for us faster
than if I just have access to raw PHP/MySQL. This is currently in the
"test" debian distribution, which XMission will move to when it comes
out of test, but who knows how long that will be. At that time I'll
have the environment available to me on my xmission account.
--
"The Direct3D Graphics Pipeline" -- DirectX 9 draft available for download
<http://www.xmission.com/~legalize/book/download/index.html>
Legalize Adulthood! <http://blogs.xmission.com/legalize/>
On 3/10/07, Sridhar Ayengar <ploopster at gmail.com> wrote:
> Ethan Dicks wrote:
> > I think a 11/750 makes a fine single-user VMS "workstation" ;-)
>
> Never trust a workstation that couldn't roll over you and smash you flat?
I almost had an 11/750 land on me, but I was able to coax it out of
the side door of a Chevy Astro mini-Van (alone) without getting
squished or pinched. That was a fun experience.
Thinking about the whole "11/750 workstation" concept - I wonder if
one could take a qbus mono framebuffer and hang it off of some flavor
of Qniverter? It'd be glacial compared to a real VAXstation II or
VAXstation 2000, but presuming the framebuffer doesn't depend on
anything peculiar to POST on a MicroVAX II, it'd be slick to see. For
"real" work on an 11/750, any flavor of DMA-capable Unibus comms
interface (DEC DMF-32, Emulex CS21...) and an authentic
ANSI-compatible dumb terminal (VT100, VT220...) is just fine (but back
in the day, the "power users" had two terminals on their desk, along
with a serial switch box to manage "multiple sessions" in hardware).
-ethan
Speaking as a youngster (I was in the sort-of midrange bracket, my
elementary/middle school had a reasonably well equipped Apple IIc (&
clone)/ IIgs lab that we actually learned programming on, then high
school had 2 XT clones and 2 Mac Pluses for general use, and about 25
386s kept under lock and key for learning typing, then when I got to
college I missed the VAX years-we were on Suns) the DEC bit was due
partially to reputation and, perhaps, partially due to advertising
(after the children's programming on PBS they ran McNeil/Lehrer, and
right at the start they did the "brought to you by Digital Equipment"
with the Digital logo. Still remember that).
Anyway- I was old enough to remember the technical buzz about Alpha
when it came out, and of course I later learned how 4BSD was written on
and for VAXen. I don't have a huge DEC collection (VAX 4000/200,
VAXstation 3100/76 (cobbled together, it seems to mostly work) DEC
3000, AlphaServer 1000a, Multia (my first machine, I was getting
desparate...)
Haven't found any PDPs in the area/within my price range, but based on
my experience there are two manufacturers who do really nice console
firmware, one of them is DEC (SRM/later VAX consoles), and the other is
Sun. DEC marketing was terrible, though (arbitrary hardware limits,
extreme proprietariness, random direction changing (sounds a bit like
SGI...) It's a testament to DEC engineering, though, that HP hasn't
been able to kill off the Alpha after several years of trying. It's
back, at least for another month.
It will be interesting to see what today's children are interested in.
AFAIK few school districts do programming now, and most are running
PCs.
I've been out in my shop this morning getting some VT52 DecScopes out of the back corner to prep them for shipping. I decided to boot up the old Wofford Witch PDP-11/40, since it has not been booted since November. While it's up and running, I think I am going to set up my camcorder and take some videos of the front panel as the lights blink, the LA120 Decwriter III console during the RSTS/E V7 startup process, the ASR-33 teletype as it clanks away running SYSTAT, the VT05 terminal during a video display, as well as the LA36, VT52, RL02, RK05, etc.
I will hopefully find time to put these videos on my web site http://www.woffordwitch.com later today.
I will show how to load an RL02 pack, an RK05 pack, etc. Is there anything in particular anyone is interested in while I am making videos?
Hopefully someone will find these little video clips interesting or useful. I know that there have been times in the past where somebody would acquire an RL02 drive or RK05 drive and wish that someone could show them how to load a disk pack properly.
Let me know if there is anything else that might be of interest while I have a few minutes and am not being summoned by "she who must be obeyed". :-)
Ashley
http://www.woffordwitch.com
Here's my six cents...
I worked for DEC (twice).
Better engineering and nicer group of people you would not find
again.
Rod Smallwood
DEC Badge No 45083
-----Original Message-----
From: cctech-bounces at classiccmp.org
[mailto:cctech-bounces at classiccmp.org] On Behalf Of Ethan Dicks
Sent: 10 March 2007 02:26
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: Value of a PDP/8?
> > Someone (Jules? broken attribution?) wrote:
> > I feel the need to ask - what is it that makes DEC stuff so popular
> > and collectible, versus other machines of the same time period?
> >
> > So... why? More of a community? Better documentation? Better
> > hardware or software availability? What do collectors *do* with
> > their running DEC systems anyway?
Familiarity - for me, as well as many members of this list, it's a
matter of accumulated experience on DEC boxes when they were new or
recently retired.
> I can only speak to my own reasons. It really comes down to 2 issues.
>
> When I started collecting DEC hardware it was pretty cheap on the
> surplus market. My 11/05 cost $50.00 US and was runnable. Another $150
> and I had a pair of RX01's. The most expensive part was RAM.
Nice start. As I've posted in the past, my start with DEC hardware was
a $35 PDP-8/L in 1982 from the Dayton Hamvention. It took me 2 years of
fiddling around with it until I ran across a copy of the module list and
got it working. From there, it was to a PDP-8/a to which I added an
RX8E/RX01 then an RL8A and RL01 and a VT52.
Coincident with the PDP-8/a, I was using PDP-11s and VAXen at work, so I
was pretty well established as a DEChead between High School and my
Freshman year of College. I never got paid to program a PDP-8, but I'm
happy I barely made the cutoff to program the PDP-11 for a living
(1986-1987).
Besides early access to the hardware, I'd say the appeal was how much
cooler 12-bits and 16-bits and 32-bits was compared to my little 6502
and 1802 machines were at home. I could write "real" programs on a
minicomputer at work or poke around with noddy stuff in BASIC and 6502
assembler at home. No contest. It didn't hurt that while I was
learning PDP-11 machine language at work (typing in diagnostics with
console ODT emulators), I was also working on Unibus and Qbus hardware.
I got to learn all the low-level stuff _and_ get a paycheck for it. I
never saw an HP or Data General in the flesh until several years after I
was repairing PDP-11 boards and writing programs in MACRO and C.
Speaking of C, I learned it on an 11/750 running 4BSD in 1985. A
venerable platform if ever there was one (back in the days of "all the
world's a VAX"). I learned the One True Brace formatting standard in
that environment and retain that style to this day.
So... in short - early exposure and access, then the chance to pick up
older stuff on the surplus market for cheap or free. When nobody wanted
5MB RL01s, I was buying cheap RL01s. Later it was RL02s, then it was
entire MicroVAXen, etc. So much of it was backwards and forwards
compatible, I could play with what I could afford at home, then take my
results to work and run stuff on really expensive iron ($100K+).
Shame it's all so hard to find now.
-ethan
>> Then I looked at the pictures, and saw it was made by my old
>> employers, Marconi Avionics who took over Elliott Brothers, and
>> continued to make 920 series machines. I think there were 12 bit
>> versions made by one of the divisions, though I am surprised they
>> were still making them in the 1980s.
> Yes, the unit was made after 1986 I think. One quy in the
> rec.aviation.military claimed, that the box might be from
> early tornados as I mentioned in my original posting. I do
> not know how long development of such an aircraft takes but
> the first take-off was in 1974 I think, so this would match
> the design of this box wuite well - what do you think?
Aircraft development takes a long long time. To make it worthwhile
the aircraft has a long service life. Whilst the computers are bullet
proof in an office/home, the temperature extremes, vibration, high G
forces etc in service means that many failures occur and PCBs could
be replaced many times over the years, so do not pay too much notice
of the dates on components of the boards currently installed.
There were at least four 12 bit versions, and one 13 bit apparently.
Then 12 bit models were the 902, 102C, ARCH 105 and Minim or 12/12.
>
>> One part of Elliott Brothers became GEC Computers (based in
>> Borehamwood).
> Yes, that matches - the core memory module already has the
> label GEC. So this is (as I suspected) older than the CPU and
> taken maybe from a different design?!
You have it the wrong way around. The GEC name replaced the Marconi
name, which had earlier replaced Elliott. Core memory was very
convenient for military applications and was in use long after it was
replaced in commercial applications. Think of a missile or torpedo
held in stock for many years, stick a power plug into it and program
the target, pull out the plug and then launch it. Only then does the
internal power supply come up, the processor boots up and does its
thing.
>
>> One of your labels is from Airborne Displays Division based at the
>> same Rochester site as I worked. This was also part of Marconi
>> Avionics, and the company later changed its name to GEC Avionics. I
>> worked on compilers, linkers and other utility software for the 18
>> bit 920s before moving on to the Zilog Z8001.
> Hey, than you are a valuable expert on these - do you have
> got any source of intormation about the 920s?
Not directly but I may be able to help.
>
>> Erik, could you tell me if the instruction code is anything like
>> this:
>> 0 Load B (indexing) register and the Q register (shift extension)
>
> RIGHT
>
>
>> 1 Add to accumulator
>
> RIGHT
>
>
>> 2 Negate and add to accumulator
>
> RIGHT
>
>
>> 3 Store the Q register
>
> RIGHT
>
>
>> 4 Load accumulator
>
> RIGHT
>
>
>> 5 Store accumulator
>
> RIGHT
>
>
>> 6 And to accumulator
>
> RIGHT
>
>
>> 7 Jump if zero
>
> RIGHT
>
>
>> 8 Jump
>
> RIGHT
>
>
>> 9 Jump if negative
>
> RIGHT - all three jumps are relative ones
On the 18 bit machines these were relative to the start of the 8k
memory module the instruction was in. An interesting modification.
>
>
>> 10 Increment
>
> RIGHT
>
>
>> 11 Store program counter (for function return)
>
> SIMILAR - This stores PC and then does a
> table jump
On the 18 bit machines, it actually stored the program counter + 1
and the following instruction was either an 8 or a "/8", i.e. 24.
>
>
>> 12 Multiply
>
> RIGHT, unsigned multiplication
This should multiply the signed accumulator and the signed memory
operand giving a double length result in the A and Q registers.
>
>
>> 13 Divide
>
> HMMM, the command takes very long but the results are
> very strange. I thought it might be some type of
> random number generation by an irreducible polynomal,
> but it is definitively not Divide. Maybe here is something
> different or wrong with the microcode.
This divides a signed DOUBLE LENGTH number in the A and Q registers
by a signed memory operand. IIRC the A register gets the result and
the Q register the remainder.
>
>> 14 Shift
>
> In PART: Here exist many subgroups of commands including
> shift left/right. Also the Q as you call it can be transferred
> to Accu and vice versa. There als is a MTA (MoveToAccu as I call it)
> which is a two-word instruction (most others are one-word) and
> transfers the word following this command into Accu. About
> 16 bit patterns have (at least to me now) the same meaning in
> this segment.
Shifting by the entire word length does transfer Q to A or A to Q
(but the data disappears from the source). A load immediate
instruction would have been very handy. There was also a block move
instruction here in the 18 bit machines. Maybe some of the special 15
orders were encoded in the 14 order on the 12 bit machines with only
256 numbers available compared with 8k on the 18 bitters.
>
>
>> 15 Input/Output and special (like interrupt return)
>
> Yes, in part as well. Commands for sending and receiving
> via the serial links I found here.
>
>> 16 to 31, as above but indexed by B register.
>
> NOPE - The box is 12-bit and does not have got this block.
> EVERYTHING is done via the index register I as I called it.
Do you mean you cannot turn the B-register modification off?
Does it get cleared automatically somehow?
>
>
>
> So
>
> #######
> # # # ##### ###### # # ##
> # # # # # # # # # #
> ##### # # # # ##### #### # #
> # # # ##### # # # ######
> # # # # # # # # # #
> ####### #### # # ###### # # # #
Eh?
>
> the box is a 12-bit version of the Elliot series of Computer.
> Lot of work for rediscovering the instruction set of the 920
> Elliot...
>
> Roger, do you have got any detailed information on these
> you are willing to share with me! I am familar with the above
> mentioned instruction set, but some details are still open and
> perhaps studying the Elliot would help to solve the remaining
> problems??!?!?!!
I am willing to try.
By the way, there are two 't's in Elliott.
>
>> In early versions of the 920, the B and Q registers were the same
>> register and it and the program counter were held in memory. There
>
> In this box the registers are stored in "batteries" of 74xxx flip
> flops on the processor boards.
On the later 920s, the current interrupt levels B register and
sequence control register (i.e. program counter) were held in real
registers but the other interrupt ones were held in memory. There was
extra circuitry to make it so that writing to the current level's B
register address actually got trapped and also modified the real
register.
>> were four levels of interrupt and a set of these registers for each,
>> held in location 0 to 7. The high end of memory held a paper tape
>> bootstrap, in later versions, this was just copied into core when the
>> machine was initialised.
> Interesting. The Programmer Electronic Control starts execution
> at 0x0a0 after reset.
Could it be that there is a value of 0x0A0 at location 0?
> But of course the application was different
> and the operation software was completely loaded via the big plug
> boefore operation.
I suspect the big plug is for the OMP (Operator's Monitor Panel), and
yes the program would be loaded via this once, probably in the
factory or at a maintenance depot, and the machine would probably be
rebooted many times afterwards.
>
>> If this indeed a military machine, you can be sure the memory was
>> erase by flipping every bit backwards and forwards several hundred
>> times to remove any trace magnetism before it was released from
>> the RAF.
> Yes you are probably right. I thought just in case there are some
> fragements inside it would have been interesting to study them
> in order to learn about the instruction set.
>
> I am sure the unit supports interrupts (one for each serial
> port (panavia link I think) and maybe there is an additional
> for the timer. This timer has a reload register and
> thus can be programmed to arbitrary intervals (12bit, running
> at 2MHz). But up to now I was not able to read or write it
> nor occured an interrupt. Here studying the Elliot would
> really be inspiring - I am very sure that they reused the
> know how here as well...
The 920 was unusual in that it booted into the highest level
interrupt, level 1, so no interrupts will be serviced until you go
down an interrupt level or two or three.
The 15 order is coded thus:
15 0 to 2047 Input
15 2048 Shift A register left 7 places and OR in a character from the
paper tape reader (via OMP)
15 2052 (IIRC) Wait until character pressed on teletype and read into
A register (via OMP)
15 4096 to 6143 Output
15 6144 Output character to paper tape punch (via OMP)
15 6148 Output character to teletype (via OMP) if I remember correctly
15 7168 Terminate current program level i.e. return from interrupt
15 7169 Test if standardised IIRC, skip the next instruction if the
accumulator is zero or top two bits are different
15 7170 Increment B and skip the next instruction if bottom 13 bits
are zero
15 7171 Read the value of the control keys on the OMP
15 7172 Move l.s. 17 bits of A to the m.s. 17 bits of Q. Bottom bit
of Q is zeroed
15 7173 Move m.s. 17 bits of Q to l.s. 17 bits of A. Top bit of A is
zeroed
15 7174 Move A to B
15 7175 Move B to A
15 7176 Set relative addressing mode
15 7177 Set absolute addressing mode
In relative mode, all addresses are relative to the start of the 8k
block of memory the instruction is in. In absolute mode (the
default), 7,8 and 9 orders are still relative but in all others the
address is absolute, so that only the bottom 8k of memory is
accessible without using B modifiers.
Roger Holmes.