[cctalk] Re: Talking PDP11

[Jon Elson via cctalk]

On 7/10/23 11:19, Douglas Taylor via cctalk wrote:
I'm looking to see if it possible to do something 
similar.  Just blasting raw 12bit samples from memory out 
the D/A board.
A fine point would be to use the KWV11-C realtime clock 
board for the sample rate control.  No interrupts, just 
polling.


Harder is taking an existing MPG or WAV audio clip and 
converting it into raw 12bit integers.
I wouldn't try this on the PDP11, I would do this in 
Linux, offline, using python or octave to take a wide band 
audio file convert it into a narrowband audio file, then 
resample down to the rate I would use on the PDP11 and 
finally convert the numbers into 12bit integers.


I think audacity will convert to any arbitrary sample rate.  
I'm not sure if there's a way to set the bits/sample, but if 
you turn the volume down you should be able to just truncate 
the data.


Jon

[cctalk] Re: Talking PDP11

[Paul Koning via cctalk]

> On Jul 9, 2023, at 9:19 PM, Douglas Taylor via cctalk  
> wrote:
> 
> Wow! Actual engineers responding...
> 
> It looks like I could only do the most rudimentary audio.
> 
> 1. Sample Rate: You got maybe 20K samples to store in lower memory.  At 7KHz 
> sample rate that would allow 3 seconds of audio.  Voice only.
> 2. Samples: They must be 12 bits. Converting a modern audio clip requires, 
> band filtering, resampling and mapping to 12 bit integers.  Could be done in 
> python, they have libraries.
> 3. Clocking output:  I have a KMV11, but never programmed  around it.
> 4. Amplify output: AAV11-C produces -10 to +10 volts, have to divide this 
> down for input to an audio amp.
> 
> In the end I will have undone all the advances made in digital audio in the 
> last 30 to 40 years.

I'm reminded of a project I did in college in 1974, when I made a primitive 
graphics display using an X/Y oscilloscope driven by an AA-11.  Since the 
machine was a PDP-11/20 with 8 kW of memory, I decided to use the RC-11 disk as 
the refresh memory, doing DMA directly from disk to the D/A data CSR.

So on the scenario here: the sample rate is clearly more than adequate.  12 
bits is not CD grade audio but not bad; for ears used to the distorions of 
compressed audio files it's probably good enough.  

The PDP-11 certainly won't be able to decompress modern lossy compression 
files.  It should be fine with raw or nearly-raw files, which means you can 
convert externally and feed the resulting files to the PDP-11.  You could 
convert to 16 bit raw mono with standard tools and then drop the bottom 4 bits. 
 Band filtering?  Resampling?  I don't know why you would want to do that, 
unless there isn't a reasonable way to drive the device at the source file's 
data rate.  For example, if you have a KW-11/P that's clearly doable.  (Come to 
think of it, that 11/20 had a KW-11/P and I created BASIC extensions for it 
that would allow sampling to be driven by that clock, at a rate of your 
choosing.)

You can't fit a whole lot of data in 64 kW of memory, but that isn't needed.  
That rate isn't all that high; it isn't hard to write a program that does 
double buffering from a disk file to memory to the D/A.  That makes a really 
nice real time programming exercise.

paul

[cctalk] Re: 1-click exploits was Re: BEWARE: Phishing

[geneb via cctalk]

On Sun, 9 Jul 2023, Todd Pisek via cctalk wrote:


Be aware that clicking on a malicious url can result on malware or spyware 
being installed on your machine without any further action on your part. All 
browsers have vulnerabilities. The most famous of these was the older version 
of Pegasus by NSO back in the 2014-2016 timeframe. These so called 1-click 
exploits are well known to bad actors. It?s a continuous cat and mouse game 
between exploit writers and infosec. For the interested, look at this report 
regarding Apple and the ?Trident? series of exploits from 2016.

https://info.lookout.com/rs/051-ESQ-475/images/pegasus-exploits-technical-details.pdf



Excellent advice.  I'd also point out that malware can be served up by ad 
networks, so it's also in your best interests to install the Privacy 
Badger and U-Block Origin plugins to whatever browser you use.


If you're /really/ paranoid, read email with Alpine.  You'll never get 
phished when it's painfully obvious where a link *really* goes. ;)


g.


--
Proud owner of F-15C 80-0007
http://www.f15sim.com - The only one of its kind.
http://www.diy-cockpits.org/coll - Go Collimated or Go Home.
Some people collect things for a hobby.  Geeks collect hobbies.

ScarletDME - The red hot Data Management Environment
A Multi-Value database for the masses, not the classes.
http://scarlet.deltasoft.com - Get it _today_!

[cctalk] A from-scratch PDP 11 OS - ruos

[Alan Kirby via cctalk]

A friend suggested that some in this group may have an interest in this.

ruos stands for Retro Useless Operating System
ruos is an OS for the long-obsolete PDP11/70 from Digital Equipment 
Corporation. ruos runs on the simh simulator for that machine. It was written 
completely from scratch in C and assembler. On a modern machine, the kernel and 
user code builds in a few seconds.
Overview:
It can run something less than 64 processes simultaneously with one user on the 
console and others on other serial ports. Equal priority CPU-bound tasks share 
the CPU.
The user program API includes a number of stdio-like C functions
ruos was built using the gcc toolchain for the PDP11 (Thanks for those 
toolchain bug fixes Paul Koning!)
Each user process is given exactly 64kB for code, data, heap, and stack and is 
(mostly) isolated from other processes
Users access the OS using a  very simple unix-like shell for command execution 
with pipes allowed
It does not have its own file system but uses a proxy for file IO. The proxy 
code (Python 3) is included.
Communication between the OS and the proxy is via UDP/IPv4/Ethernet.
Familiar user binaries include: cat, ps, echo, grep. Device status is provided 
by ds
If a user tries to run a program that is not native to ruos, an attempt is made 
to run it on the proxy. Using this mechanism, users can edit files or build new 
programs (assuming the gcc toolchain is installed on the proxy and the proxy is 
on the same machine as simh).

It is accessible here:
https://ajco...@bitbucket.org/ajcorbeil/ruos.git 



Regards,


Alan Kirby

[cctalk] Re: Talking PDP11

[Sellam Abraham via cctalk]

On my Apple ] [ with 48k memory I used to be able to sample audio from the
cassette port and store about 30 seconds of audio that was fairly decent
quality upon playback. With a 1MB RAM board installed I was able to sample
the entire ~5 minutes of Led Zeppelin's Over The Hills And Far Away from
their Houses of the Holy album.

Sellam

On Mon, Jul 10, 2023, 6:41 AM Paul Koning via cctalk 
wrote:

>
>
> > On Jul 9, 2023, at 9:19 PM, Douglas Taylor via cctalk <
> cctalk@classiccmp.org> wrote:
> >
> > Wow! Actual engineers responding...
> >
> > It looks like I could only do the most rudimentary audio.
> >
> > 1. Sample Rate: You got maybe 20K samples to store in lower memory.  At
> 7KHz sample rate that would allow 3 seconds of audio.  Voice only.
> > 2. Samples: They must be 12 bits. Converting a modern audio clip
> requires, band filtering, resampling and mapping to 12 bit integers.  Could
> be done in python, they have libraries.
> > 3. Clocking output:  I have a KMV11, but never programmed  around it.
> > 4. Amplify output: AAV11-C produces -10 to +10 volts, have to divide
> this down for input to an audio amp.
> >
> > In the end I will have undone all the advances made in digital audio in
> the last 30 to 40 years.
>
> I'm reminded of a project I did in college in 1974, when I made a
> primitive graphics display using an X/Y oscilloscope driven by an AA-11.
> Since the machine was a PDP-11/20 with 8 kW of memory, I decided to use the
> RC-11 disk as the refresh memory, doing DMA directly from disk to the D/A
> data CSR.
>
> So on the scenario here: the sample rate is clearly more than adequate.
> 12 bits is not CD grade audio but not bad; for ears used to the distorions
> of compressed audio files it's probably good enough.
>
> The PDP-11 certainly won't be able to decompress modern lossy compression
> files.  It should be fine with raw or nearly-raw files, which means you can
> convert externally and feed the resulting files to the PDP-11.  You could
> convert to 16 bit raw mono with standard tools and then drop the bottom 4
> bits.  Band filtering?  Resampling?  I don't know why you would want to do
> that, unless there isn't a reasonable way to drive the device at the source
> file's data rate.  For example, if you have a KW-11/P that's clearly
> doable.  (Come to think of it, that 11/20 had a KW-11/P and I created BASIC
> extensions for it that would allow sampling to be driven by that clock, at
> a rate of your choosing.)
>
> You can't fit a whole lot of data in 64 kW of memory, but that isn't
> needed.  That rate isn't all that high; it isn't hard to write a program
> that does double buffering from a disk file to memory to the D/A.  That
> makes a really nice real time programming exercise.
>
> paul
>
>

[cctalk] Re: Talking PDP11

[Mike Katz via cctalk]

Doug,

You could also do some kind synthesizer using fixed frequencies and 
pulse width modulation.


It would not be that difficult to add attack and decay and even be 
polyphonic.


You could either use the keyboard for single tone with different keys to 
change the PWM, Attack, Decay, white noise, pink noise, and volume of 
each channel or you could write some kind of interpreter that would play 
music from some kind of text file.


Way back in the 80's I was able to do stereo 4 part harmony on a 2 MHZ 
6809 using two 8-bit D/A converters.


If you want to generate different waveforms they can be stored in memory 
and the faster you cycle through them the higher the frequency.  
However, the finer the resolution the greater the memory requirement.


Square waves are the easiest to produce as they don't need waveform 
tables.  Just remember you need to remember the Nyquist frequency. You 
need to be writing to the D/A at at least double the frequency of the 
tone you are trying to product.  However,  twice the frequency only 
allows you to produce square waves.


I would look at the output of your program on an oscilloscope to see if 
there is any high frequency artifacts that you might want to filter out 
electronically.


Have fun and please post some recordings.

On 7/9/2023 10:07 PM, Martin Bishop via cctalk wrote:

Doug

You have the essence of what it can do and how it might do it, an old iron 
PDP-11 / LSI-11 can't organically do the signal processing necessary to go from 
a compact signal representation to audio.  That said you could use a one bit 
output, which would for efficiency require a serialiser, to drive a sigma delta 
converter, e.g. 
https://digilent.com/shop/pmod-i2s2-stereo-audio-input-and-output/, to convert 
a word stream to sound.  Generating the I2S bit stream is of course an XFU, 
probably doable from a DRV11 type interface, with a fair bit of logic or your 
favorite microcontroller as intermediary.

A 7 kHz sample rate will not be easily achieved, unless you can use an external clock or plug in an 
"optimal" oscillator, e.g. the classic example (but not for this requirement) is one 
running at a multiple of baud rate frequencies, 12M288 Hz say.  On these old boards, frequency = 
oscillator / prescaler / divisor.  Generally, the divisor is the "round" number and the 
frequency is the fractional mess.  Also, the prescalers may be powers of two, ten, or 1/2/5 : YMMV.

The sort of thing you could demonstrate as audio output from your hardware is 
either Morse or audio composed of phonemes.  The Morse would require some 
evolution of the test generator I described and a little tapering of the attack 
/ decay of the di dah dit sounds to avoid harshness, or could be done from 
canned waveforms (returning to 0V).  The phonemes might generate text to speech 
of 1980's (i.e. contemporary period) standard.

Have fun

Martin

-Original Message-
From: Douglas Taylor via cctalk [mailto:cctalk@classiccmp.org]
Sent: 10 July 2023 02:20
To: Martin Bishop via cctalk 
Cc: Douglas Taylor 
Subject: [cctalk] Re: Talking PDP11

Wow! Actual engineers responding...

It looks like I could only do the most rudimentary audio.

1. Sample Rate: You got maybe 20K samples to store in lower memory.  At 7KHz 
sample rate that would allow 3 seconds of audio.  Voice only.
2. Samples: They must be 12 bits. Converting a modern audio clip requires, band 
filtering, resampling and mapping to 12 bit integers. Could be done in python, 
they have libraries.
3. Clocking output:  I have a KMV11, but never programmed  around it.
4. Amplify output: AAV11-C produces -10 to +10 volts, have to divide this down 
for input to an audio amp.

In the end I will have undone all the advances made in digital audio in the 
last 30 to 40 years.

Doug

On 7/9/2023 4:09 PM, Martin Bishop via cctalk wrote:

You just did use it to play "audio" :<)

The 6 us settling time corresponds to a sampling rate of ~167 kHz, not that you 
will ever get there or would wish to.

The theoretical (real) sampling rate required for a given bandwith is
Fs = 2 Bw.  That requires brick wall filters and it is a lot of work
to get close without significant distortion.  These old DACs are all
but certain to use ladder circuits [see e.g.
https://en.wikipedia.org/wiki/Resistor_ladder] the settlng time will
mostly come from the output buffer [see e.g.
https://www.analog.com/en/technical-articles/ltc1668-dac-lt1807-opamp-
achieve-90ns-settling-to-16bits-83db-sfdr-small-footprint.html for
bleeding edge examples].  To see something other than ringing on a
scope you want at least 10 samples per cycle, e.g. for 3 kHz bandwidth
(i.e. 0 - 3 kHz frequency coverage) output at 30 kHz or greater.  A
low pass (reconstruction in the argot) filter will round off the
corners - set the corner just above the passband

DMA, a local FIFO or at least double buffering are the minimum to
avoid sample jitter.  On basic hardware you will probably have to do
what you can with a 

[cctalk] OLD ftp.compaq.com Mirror?

[Ali via cctalk]

Hello All,

I am wondering if anyone has a private or knows of a mirror for
ftp.compaq.com that is older than 2014? All the ones I have found online,
including the file at archive.org, are from 2014. By then a number of files
and directories had been purged e.g. "/pub/supportinformation/techpubs" and
"softlib1". I am looking for some old documentation and firmware for Compaq
switches and Tape Libraries but if anyone has a full set of files I am happy
to add them to a mirror. TIA!


-Ali

[cctalk] Re: Talking PDP11

[Douglas Taylor via cctalk]

I'm looking to see if it possible to do something similar.  Just 
blasting raw 12bit samples from memory out the D/A board.
A fine point would be to use the KWV11-C realtime clock board for the 
sample rate control.  No interrupts, just polling.


Harder is taking an existing MPG or WAV audio clip and converting it 
into raw 12bit integers.
I wouldn't try this on the PDP11, I would do this in Linux, offline, 
using python or octave to take a wide band audio file convert it into a 
narrowband audio file, then resample down to the rate I would use on the 
PDP11 and finally convert the numbers into 12bit integers.


Then just deposit those 12bit numbers into the PDP11 memory and blast away!

Will it work?  I don't know.

Anyway, it's July and too hot to go outside.  This is an inside project, 
with air conditioning.


Doug

On 7/10/2023 9:41 AM, Paul Koning via cctalk wrote:



On Jul 9, 2023, at 9:19 PM, Douglas Taylor via cctalk  
wrote:

Wow! Actual engineers responding...

It looks like I could only do the most rudimentary audio.

1. Sample Rate: You got maybe 20K samples to store in lower memory.  At 7KHz 
sample rate that would allow 3 seconds of audio.  Voice only.
2. Samples: They must be 12 bits. Converting a modern audio clip requires, band 
filtering, resampling and mapping to 12 bit integers.  Could be done in python, 
they have libraries.
3. Clocking output:  I have a KMV11, but never programmed  around it.
4. Amplify output: AAV11-C produces -10 to +10 volts, have to divide this down 
for input to an audio amp.

In the end I will have undone all the advances made in digital audio in the 
last 30 to 40 years.

I'm reminded of a project I did in college in 1974, when I made a primitive 
graphics display using an X/Y oscilloscope driven by an AA-11.  Since the 
machine was a PDP-11/20 with 8 kW of memory, I decided to use the RC-11 disk as 
the refresh memory, doing DMA directly from disk to the D/A data CSR.

So on the scenario here: the sample rate is clearly more than adequate.  12 
bits is not CD grade audio but not bad; for ears used to the distorions of 
compressed audio files it's probably good enough.

The PDP-11 certainly won't be able to decompress modern lossy compression 
files.  It should be fine with raw or nearly-raw files, which means you can 
convert externally and feed the resulting files to the PDP-11.  You could 
convert to 16 bit raw mono with standard tools and then drop the bottom 4 bits. 
 Band filtering?  Resampling?  I don't know why you would want to do that, 
unless there isn't a reasonable way to drive the device at the source file's 
data rate.  For example, if you have a KW-11/P that's clearly doable.  (Come to 
think of it, that 11/20 had a KW-11/P and I created BASIC extensions for it 
that would allow sampling to be driven by that clock, at a rate of your 
choosing.)

You can't fit a whole lot of data in 64 kW of memory, but that isn't needed.  
That rate isn't all that high; it isn't hard to write a program that does 
double buffering from a disk file to memory to the D/A.  That makes a really 
nice real time programming exercise.

paul

[cctalk] Re: OLD ftp.compaq.com Mirror?

[Ali via cctalk]

> I can't help with the mirror, but maybe I can help with the old
> spinning
> plastic that I have related to ProLiants and / or StorageWorks stuff.
> 
> Please clarify what you're looking for and I'll see if anything I have
> is germane.

Hi Grant,

I am currently looking for the following:

Firmware for the MSL5000 Tape Library (version 5.20). The file name would be 
something like Nextgen_520.bin. The MSL5000 is a rebranded Overland library. 
Apparently you could have used the original Overland firmware in the MSL5000 as 
well but Overland doesn't have any of the info/files up on that model any more 
either after the merger with Tandenberg...

The manual for the SW5450 Switch Manual and any FW updates (not sure if there 
was any).
Any FW later then 1.01 for the SW332x series of dual speed switches.

TIA!

-Ali

[cctalk] Re: OLD ftp.compaq.com Mirror?

[Ali via cctalk]

> I am surprised the original Compaq diagnostics for 5 1/4"- native
> systems
> and early DOS and even OS/2 are not someplace

Bill,

I think those are out there. I believe the last version for DOS was 8.x and 
that is in the first 500 Softpaqs. I can find the exact number for you if you 
are interested.

-Ali

[cctalk] Re: OLD ftp.compaq.com Mirror?

[John H. Reinhardt via cctalk]

I just found this the other day, but I see the update date in in 2014 so it may 
not be of use.

http://ftp.zx.net.nz/cgi-bin/archive-mirror

There is some info about libraries under the Storageworks folder.

https://ftp.zx.net.nz/pub/archive/ftp.compaq.com/pub/products/storageworks/

--
John H. Reinhardt


On 7/10/2023 10:54 AM, Ali via cctalk wrote:

Hello All,

I am wondering if anyone has a private or knows of a mirror for
ftp.compaq.com that is older than 2014? All the ones I have found online,
including the file at archive.org, are from 2014. By then a number of files
and directories had been purged e.g. "/pub/supportinformation/techpubs" and
"softlib1". I am looking for some old documentation and firmware for Compaq
switches and Tape Libraries but if anyone has a full set of files I am happy
to add them to a mirror. TIA!


-Ali

[cctalk] Re: Talking PDP11

[Paul Koning via cctalk]

> On Jul 10, 2023, at 12:19 PM, Douglas Taylor via cctalk 
>  wrote:
> 
> I'm looking to see if it possible to do something similar.  Just blasting raw 
> 12bit samples from memory out the D/A board.
> A fine point would be to use the KWV11-C realtime clock board for the sample 
> rate control.  No interrupts, just polling.

In the case I mentioned I could use the "inhibit bus address increment" feature 
of the RC11 controller (and a number of other older controllers) so a long DMA 
would send every 16-bit data word to the same bus address (the AA11 data CSR).  
That may not be an option for you.  If not, you'd have to read from disk while 
simultaneously sending to the D/A, which is a simple exercise in asynchronous 
I/O programming.

> Harder is taking an existing MPG or WAV audio clip and converting it into raw 
> 12bit integers.
> I wouldn't try this on the PDP11, I would do this in Linux, offline, using 
> python or octave to take a wide band audio file convert it into a narrowband 
> audio file, then resample down to the rate I would use on the PDP11 and 
> finally convert the numbers into 12bit integers.

You could certainly downsample if you want to, but as was already observed the 
hardware can handle standard audio data rates of 44.1 k (CD rate) or 48 k (the 
other common rate) directly.  That also avoids the need for much if any 
filtering of the output, since the aliases would be above the audible range.

paul

[cctalk] Re: OLD ftp.compaq.com Mirror?

[Ali via cctalk]

> I just found this the other day, but I see the update date in in 2014
> so it may not be of use.
> 
> http://ftp.zx.net.nz/cgi-bin/archive-mirror

John,

Thanks. Actually I have been talking to David (the maintainer/owner of that 
mirror) and he doesn't have those files either.

> 
> There is some info about libraries under the Storageworks folder.
>

 
> https://ftp.zx.net.nz/pub/archive/ftp.compaq.com/pub/products/storagewo
> rks/

Thanks I will check it out.

-Ali

[cctalk] Re: OLD ftp.compaq.com Mirror?

[Grant Taylor via cctalk]

On 7/10/23 10:54 AM, Ali wrote:

Hello All,


Hi,

I am looking for some old documentation and firmware for Compaq 
switches and Tape Libraries but if anyone has a full set of files I 
am happy to add them to a mirror. TIA!
I can't help with the mirror, but maybe I can help with the old spinning 
plastic that I have related to ProLiants and / or StorageWorks stuff.


Please clarify what you're looking for and I'll see if anything I have 
is germane.




Grant. . . .

[cctalk] Re: OLD ftp.compaq.com Mirror?

[Bill Degnan via cctalk]

I am surprised the original Compaq diagnostics for 5 1/4"- native systems
and early DOS and even OS/2 are not someplace

On Mon, Jul 10, 2023, 1:07 PM John H. Reinhardt via cctalk <
cctalk@classiccmp.org> wrote:

> I just found this the other day, but I see the update date in in 2014 so
> it may not be of use.
>
> http://ftp.zx.net.nz/cgi-bin/archive-mirror
>
> There is some info about libraries under the Storageworks folder.
>
> https://ftp.zx.net.nz/pub/archive/ftp.compaq.com/pub/products/storageworks/
>
> --
> John H. Reinhardt
>
>
> On 7/10/2023 10:54 AM, Ali via cctalk wrote:
> > Hello All,
> >
> > I am wondering if anyone has a private or knows of a mirror for
> > ftp.compaq.com that is older than 2014? All the ones I have found
> online,
> > including the file at archive.org, are from 2014. By then a number of
> files
> > and directories had been purged e.g. "/pub/supportinformation/techpubs"
> and
> > "softlib1". I am looking for some old documentation and firmware for
> Compaq
> > switches and Tape Libraries but if anyone has a full set of files I am
> happy
> > to add them to a mirror. TIA!
> >
> >
> > -Ali
>