Re: HP 7970E - interest to split?

[Jon Elson via cctalk]

On 09/30/2017 10:31 PM, Chuck Guzis via cctalk wrote:

On 09/30/2017 06:29 PM, Jon Elson wrote:


Ahh, but the genius is built into the heads!  Note that nobody
recorded 800 BPI on 7-track tapes. I think they supported 200 and 556
BPI, only.  There were some low-density 9-track tapes, but generally
most 9-tk tapes were 800 BPI.

Say what?   We certainly did a lot of tape at CDC at 800 NRZI on the
607s.657 and 667.   Most IBM 729s, but for the very early models could
support 800 NRZI.

800 NRZI for 9 track was common only until about 1970; 1600 PE was
available on the 2400 series.   By 1975, it had pretty much become the 9
track interchange standard.  In spite of packing more data on a piece of
tape, 1600 PE is actually more reliable than 800, as a dropped bit
transition doesn't corrupt data downstream.


OK, I never used 7 track tapes, but I thought that they were 
recorded at lower density than 9 track.

Yes, I know about 1600 PE, 3200 PE and 6250 GCR.

Jon

Re: HP 7970E - interest to split?

[Chuck Guzis via cctalk]

On 09/30/2017 06:29 PM, Jon Elson wrote:

> Ahh, but the genius is built into the heads!  Note that nobody
> recorded 800 BPI on 7-track tapes. I think they supported 200 and 556
> BPI, only.  There were some low-density 9-track tapes, but generally
> most 9-tk tapes were 800 BPI.
Say what?   We certainly did a lot of tape at CDC at 800 NRZI on the
607s.657 and 667.   Most IBM 729s, but for the very early models could
support 800 NRZI.

800 NRZI for 9 track was common only until about 1970; 1600 PE was
available on the 2400 series.   By 1975, it had pretty much become the 9
track interchange standard.  In spite of packing more data on a piece of
tape, 1600 PE is actually more reliable than 800, as a dropped bit
transition doesn't corrupt data downstream.

--Chuck

Re: HP 7970E - interest to split?

[Jon Elson via cctalk]

On 09/30/2017 12:47 PM, Chuck Guzis via cctalk wrote:

What I found a little surprising is that on a 7970 head assembly, the DC
resistance of the 9 track coils is about 76 ohms, but on the 7 track
side, the resistance measures out to about 27 ohms.

Yet, both feed into the same read amplifiers.  On the standard 7970
dual-mode drives, the switching between 7 and 9 track, is performed with
a JFET on the input.  I use small-signal DIP relays.

I would have expected a big difference in the signal levels between the two.


Ahh, but the genius is built into the heads!  Note that 
nobody recorded 800 BPI on 7-track tapes.
I think they supported 200 and 556 BPI, only.  There were 
some low-density 9-track tapes, but
generally most 9-tk tapes were 800 BPI.  So, this means that 
a transition spans less longitudinal distance along the tape.
So, you get less output from the head for an 800-BPI 
transition. For 800 BPI, they might make the head poles a 
bit shorter, but they HAD to make the gap narrower!  The gap 
must be no more than half the length of a bit, or the
signal output rapidly drops.  I'm guessing the smaller head 
poles and narrower gap forced them to use more turns of much 
smaller wire to get the signal back up to what the read amps 
need.


Jon

Re: HP 7970E - interest to split?

[Paul Koning via cctalk]

> On Sep 30, 2017, at 11:50 AM, Stefan Skoglund via cctalk 
>  wrote:
> 
> fre 2017-09-29 klockan 12:52 -0400 skrev Paul Koning via cctalk: 
>> ...
>> The approach would be somewhat similar to the disk support in SIMH, which 
>> does already have "RAW" as one of the formats, meaning direct access to a 
>> real disk.
> 
> RAW disk does that also includes using a zfs/fc/iscsi volume as disk ?
> It should considering they appear as sd{a-z} on the host.

I would assume yes, for the reason you mentioned.  But I haven't tried it.

paul

Re: HP 7970E - interest to split?

[Chuck Guzis via cctalk]

What I found a little surprising is that on a 7970 head assembly, the DC
resistance of the 9 track coils is about 76 ohms, but on the 7 track
side, the resistance measures out to about 27 ohms.

Yet, both feed into the same read amplifiers.  On the standard 7970
dual-mode drives, the switching between 7 and 9 track, is performed with
a JFET on the input.  I use small-signal DIP relays.

I would have expected a big difference in the signal levels between the two.

--Chuck

Re: HP 7970E - interest to split?

[Jon Elson via cctalk]

On 09/30/2017 06:58 AM, Tony Duell via cctalk wrote:


One of my tape drives has a set of equal-value resistors connected to
each of the read channels, the others ends of the resistors being brought
out to a testpoint. You connect a 'scope there and read a skewmaster
tape. The idea is that if the read transitions all occur at the same time
(no skew) you get a pefect step on the 'scope, if some are later than
others you get a staircase. You adjust the heads for the smallest
width of the stairs.


Yes, this is the classic NRZI skew adjust testpoint.  The 
resistors sum up the read data latches, that are set by 
seeing a transition of either polarity on a data channel, 
and reset by a one-shot that is set to about half a 
character time.
You run a skew tape or a tape written with all ones.  If you 
see a square wave, all is good.  If you see a slope on the 
wave, adjust the skew adjust screws on the head mount to 
make it as straight as possible.


Jon

Re: HP 7970E - interest to split?

[Stefan Skoglund via cctalk]

fre 2017-09-29 klockan 12:52 -0400 skrev Paul Koning via cctalk: 
> > On Sep 29, 2017, at 12:33 PM, Jon Elson via cctalk  
> > wrote:
> > 
> > On 09/29/2017 10:56 AM, Henk Gooijen via cctalk wrote:
> >> 
> >> 
> >> 
> >> On a related note my plan is to make a USB-based, Pertec-compatible
> >> controller for it. Not sure how SimH connects with peripherals so I'm
> >> /very/ eager to talk with someone familiar with its workings. I'll also
> >> release all the board files and firmware as open-source. Timeline as always
> >> is completely unknown, though I do have a now-vested interest in making it
> >> work.
> 
> It looks like it only handles tape container files (.TAP files) right now.  
> But the machinery basically has a tape emulation module (sim_tape.c) which 
> has a number of functions roughly corresponding to what a tape drive does 
> (read forward, write tape mark, rewind, etc.).  It doesn't look like a 
> terribly hard task to support a real tape drive as another "container file 
> format".  One question I can think of is how OS-dependent raw SCSI access is.
> 
> The approach would be somewhat similar to the disk support in SIMH, which 
> does already have "RAW" as one of the formats, meaning direct access to a 
> real disk.

RAW disk does that also includes using a zfs/fc/iscsi volume as disk ?
It should considering they appear as sd{a-z} on the host.

Re: HP 7970E - interest to split?

[Anders Nelson via cctalk]

Hi Chuck,

How did you program compile if you were missing a semicolon? I'm assuming
you're programming in C and not scripting it somehow... Good news on that
front!

Was it typical to read a record(s) in reverse if an error was encountered?
Sounds like that might require buffering the whole record. Easy for us now
certainly.

=]

--
Anders Nelson

+1 (517) 775-6129

www.erogear.com

On Sat, Sep 30, 2017 at 1:37 AM, Chuck Guzis via cctalk <
cctalk@classiccmp.org> wrote:

> Hi Anders,
>
> I found the reason for my SD card problems--a missing semicolon.   There
> was supposed to be a stall until SDIO transfer complete; instead of a
> stall, the next statement was being executed.
>
> Argh.  It's those little things that really trip you up.
>
> At any rate, I've even got read-reverse working, so I can read a block,
> parity check it and retry automatically if there's an error.
>
> Not too shabby for a $10 MCU board.
>
> --Chuck
>
>

Re: HP 7970E - interest to split?

[Tony Duell via cctalk]

On Sat, Sep 30, 2017 at 6:32 AM, Chuck Guzis via cctalk
 wrote:

> Still a few too many read errors for my taste, so this weekend is going
> to be a session with a 'scope and alignment tape.   I think I've got a
> way to adjust skew--just hook a logic analyzer probe to each channel and
> set the LA to trigger on state changes.   The HP box I'm using is good
> to about 25 nsec.

One of my tape drives has a set of equal-value resistors connected to
each of the read channels, the others ends of the resistors being brought
out to a testpoint. You connect a 'scope there and read a skewmaster
tape. The idea is that if the read transitions all occur at the same time
(no skew) you get a pefect step on the 'scope, if some are later than
others you get a staircase. You adjust the heads for the smallest
width of the stairs.

-tony

Re: HP 7970E - interest to split?

[Chuck Guzis via cctalk]

Hi Anders,

I found the reason for my SD card problems--a missing semicolon.   There
was supposed to be a stall until SDIO transfer complete; instead of a
stall, the next statement was being executed.

Argh.  It's those little things that really trip you up.

At any rate, I've even got read-reverse working, so I can read a block,
parity check it and retry automatically if there's an error.

Not too shabby for a $10 MCU board.

--Chuck

Re: HP 7970E - interest to split?

[Chuck Guzis via cctalk]

On 09/29/2017 03:01 PM, Al Kossow via cctalk wrote:
> 
> 
> On 9/29/17 11:35 AM, Chuck Guzis via cctalk wrote:
> 
>> Does the little Kennedy drive have a vacuum takeup reel?
> 
> No, they are tension arm, very similar design to the 7970
> 
> I wanted to compare the mechanical design of the 9000 to the 7970
> but don't know if I have the time/interest any more.

No, that's not what I meant.  Some drives put a slight vacuum on the
takeup reel hub, so that the tape "sticks" to the hub--no finger hole
needed.

I've got all the programming done for the drive, including auto retries
if there's a parity error.   Reading is pretty good for 50+ year old
tapes (the ones I'm reading appear to be from the 1976 Viking missions).
 They look like session transcripts--you can see the command and the
response.

Still a few too many read errors for my taste, so this weekend is going
to be a session with a 'scope and alignment tape.   I think I've got a
way to adjust skew--just hook a logic analyzer probe to each channel and
set the LA to trigger on state changes.   The HP box I'm using is good
to about 25 nsec.

--Chuck

Re: HP 7970E - interest to split?

[Jon Elson via cctalk]

On 09/29/2017 01:35 PM, Chuck Guzis via cctalk wrote:

On 09/29/2017 09:00 AM, Al Kossow via cctalk wrote:


On 9/29/17 8:48 AM, Jon Elson via cctalk wrote:


I did a few of these on a lathe years ago.  It was a couple minutes job per 
reel.

you are also going to have to cut holes near the hub so that you can get a tape 
started
on the takeup reel.

Does the little Kennedy drive have a vacuum takeup reel?   The 7970
certainly doesn't--no fans in that box at all.  I've wondered about
applying a low-tack glue dot to the hub of the takeup reel to speed loading.



Yes, some drives had some kind of elastomer ring in the 
takeup reel that would grab most tapes and wrap them quite 
nicely with no finger hole.


Jon

Re: HP 7970E - interest to split?

[Al Kossow via cctalk]

On 9/29/17 11:35 AM, Chuck Guzis via cctalk wrote:

> Does the little Kennedy drive have a vacuum takeup reel?

No, they are tension arm, very similar design to the 7970

I wanted to compare the mechanical design of the 9000 to the 7970
but don't know if I have the time/interest any more.

Re: HP 7970E - interest to split?

[Chuck Guzis via cctalk]

On 09/29/2017 09:00 AM, Al Kossow via cctalk wrote:
> 
> 
> On 9/29/17 8:48 AM, Jon Elson via cctalk wrote:
> 
>> I did a few of these on a lathe years ago.  It was a couple minutes job per 
>> reel.
> 
> you are also going to have to cut holes near the hub so that you can get a 
> tape started
> on the takeup reel.

Does the little Kennedy drive have a vacuum takeup reel?   The 7970
certainly doesn't--no fans in that box at all.  I've wondered about
applying a low-tack glue dot to the hub of the takeup reel to speed loading.


--Chuck

Re: HP 7970E - interest to split?

[Paul Koning via cctalk]

> On Sep 29, 2017, at 12:33 PM, Jon Elson via cctalk  
> wrote:
> 
> On 09/29/2017 10:56 AM, Henk Gooijen via cctalk wrote:
>> 
>> 
>> 
>> On a related note my plan is to make a USB-based, Pertec-compatible
>> controller for it. Not sure how SimH connects with peripherals so I'm
>> /very/ eager to talk with someone familiar with its workings. I'll also
>> release all the board files and firmware as open-source. Timeline as always
>> is completely unknown, though I do have a now-vested interest in making it
>> work.

It looks like it only handles tape container files (.TAP files) right now.  But 
the machinery basically has a tape emulation module (sim_tape.c) which has a 
number of functions roughly corresponding to what a tape drive does (read 
forward, write tape mark, rewind, etc.).  It doesn't look like a terribly hard 
task to support a real tape drive as another "container file format".  One 
question I can think of is how OS-dependent raw SCSI access is.

The approach would be somewhat similar to the disk support in SIMH, which does 
already have "RAW" as one of the formats, meaning direct access to a real disk.

> MANY, MANY years ago I got a surplus Pertec key to tape system that had a 7" 
> 9-track 800 BPI NRZI drive connected to hardwired logic. You could key in 
> data, verify data by re-keying it, and read back data to a panel of light 
> bulbs.  It had core memory for the data buffer.
> 
> I found the right place to slice the sections apart and have what was pretty 
> close to the unformatted Pertec interface.
> I then wrote a mostly software-driven interface to read and write tape blocks 
> on my CP/M Z-80 system.  I created tapes and took them in to work to map them 
> and got it to write ASCII text files in VAX ANSI-D format.  It really was not 
> that complicated.  This was a read/write drive with only a single data gap.  
> So, to write and check a record, you had to write it, back up and read it.  I 
> used it for making backups.
> 
> I think you could use a Beagle Bone and the PRU microcontrollers in it to do 
> a Pertec unformatted interface.

I wonder if a BBB is fast enough that you can just drive the Pertec interface 
directly from the GPIO pins.  At 1 GHz lots of things become possible in 
software...

I noticed there is a BB "Cape" (I/O board) with a medium size FPGA on it.  
Haven't found a use for that yet, but it looks pretty powerful for those case 
where software isn't quite fast enough.

paul

Re: HP 7970E - interest to split?

[Jon Elson via cctalk]

On 09/29/2017 10:56 AM, Henk Gooijen via cctalk wrote:




On a related note my plan is to make a USB-based, Pertec-compatible
controller for it. Not sure how SimH connects with peripherals so I'm
/very/ eager to talk with someone familiar with its workings. I'll also
release all the board files and firmware as open-source. Timeline as always
is completely unknown, though I do have a now-vested interest in making it
work.


MANY, MANY years ago I got a surplus Pertec key to tape 
system that had a 7" 9-track 800 BPI NRZI drive connected to 
hardwired logic. You could key in data, verify data by 
re-keying it, and read back data to a panel of light bulbs.  
It had core memory for the data buffer.


I found the right place to slice the sections apart and have 
what was pretty close to the unformatted Pertec interface.
I then wrote a mostly software-driven interface to read and 
write tape blocks on my CP/M Z-80 system.  I created tapes 
and took them in to work to map them and got it to write 
ASCII text files in VAX ANSI-D format.  It really was not 
that complicated.  This was a read/write drive with only a 
single data gap.  So, to write and check a record, you had 
to write it, back up and read it.  I used it for making backups.


I think you could use a Beagle Bone and the PRU 
microcontrollers in it to do a Pertec unformatted interface.
The only issue is that the PRUs have a fast local memory of 
very limited size.  There is a way to open a memory
map to the ARM system memory from the PRU, although the 
shared memory is 12 K bytes, which might be enough to handle 
many uses.


I did an FPGA-based adapter to Pertec formatted interface 
using the parallel port.  (Slow, but I already had all the 
FPGA and computer side infrastructure to make that work.)  I 
have some CDC Keystone (92185) drives.


Jon

Re: HP 7970E - interest to split?

[Al Kossow via cctalk]

On 9/29/17 8:48 AM, Jon Elson via cctalk wrote:

> I did a few of these on a lathe years ago.  It was a couple minutes job per 
> reel.

you are also going to have to cut holes near the hub so that you can get a tape 
started
on the takeup reel.

RE: HP 7970E - interest to split?

[Henk Gooijen via cctalk]

Van: Anders Nelson via cctalk<mailto:cctalk@classiccmp.org>
Verzonden: vrijdag 29 september 2017 05:57
Aan: General Discussion: On-Topic and Off-Topic 
Posts<mailto:cctalk@classiccmp.org>
Onderwerp: Re: HP 7970E - interest to split?

Update: I bought the Kennedy 9800 as it pushed all my buttons at once.

Now I'm looking for 8" mag tapes/reels that will fit! Anyone know where I
can find these, maybe 3pcs? I could laser-cut some frosted acrylic or
machine some frosted polycarbonate I suppose but I'd rather just buy it,
plus that would include a dust cover.

On a related note my plan is to make a USB-based, Pertec-compatible
controller for it. Not sure how SimH connects with peripherals so I'm
/very/ eager to talk with someone familiar with its workings. I'll also
release all the board files and firmware as open-source. Timeline as always
is completely unknown, though I do have a now-vested interest in making it
work.

Be well!

Looking forward to see that controller “materialize”.

I could -give- you 3 8” mag tapes with (manual) sealing ring, but the
catch is, I am in the Netherlands.  Don’t know what shipping cost
would be, but my guess is between $25 - $35.
If you cannot get the 8” tapes over there, this might be an option.

I saw the 9800 auction briefly. Nice looking unit!  From memory, the
tape reel has the same size as fitting on the TS03?  I will measure the
reel dimensions tomorrow to make sure that they are 8”. I have open
reel tapes in 2 sizes, so probably it is 10.5” and 8”, although ISTR that
the size was 7”.

Henk

Re: HP 7970E - interest to split?

[Jon Elson via cctalk]

On 09/28/2017 11:44 PM, Anders Nelson via cctalk wrote:

Hi Chuck,

Yeah I could try that but unless I can separate the reel halves from the
hub I'd have to make a jig of sorts to absorb the laser beam on the bottom
side of the cut. Can the sides be separated? And is it possible to cut down
a dust cover?


I did a few of these on a lathe years ago.  It was a couple 
minutes job per reel.
Dust cover?  You mean the ring that goes around the reel?  
Yes, these can be cut down.
Generally, they have black plastic parts that snap into a 
hole on the end of the ring.
You take out one of the end pieces, cut the ring and then 
cut the hole in the ring that the
end piece fits into with an X-acto knife.  You may have to 
narrow the rims of the reel so the
ring fits right.  That's why the lathe is better than the 
laser cutter.  Generally, the flanges are
glued together to the hub, and you will not be able to 
disassemble them.


Jon

RE: HP 7970E - interest to split?

[Henk Gooijen via cctalk]

Van: Steve Malikoff via cctalk<mailto:cctalk@classiccmp.org>
Verzonden: vrijdag 29 september 2017 09:26
Aan: General Discussion: On-Topic and Off-Topic 
Posts<mailto:cctalk@classiccmp.org>
Onderwerp: Re: HP 7970E - interest to split?

On my Kennedy 9000s the rubber O-rings have expanded on all the spindles and a
reel has a lot of trouble being pushed on and removed. I plan to replace them 
with
neoprene O-rings of the original size. These are readily available and cheap 
from
bearing supplies stores, I'll get a range of close sizes and find the right one.

Steve.

I have read that putting the rubber rings in warm water
will make them shrink to their orginal sze, but keep their
Specifications. Worth a try …

Re: HP 7970E - interest to split?

[Steve Malikoff via cctalk]

Chuck said:
> On 09/28/2017 08:57 PM, Anders Nelson via cctalk wrote:
>> Update: I bought the Kennedy 9800 as it pushed all my buttons at once.
>>
>> Now I'm looking for 8" mag tapes/reels that will fit! Anyone know where I
>> can find these, maybe 3pcs? I could laser-cut some frosted acrylic or
>> machine some frosted polycarbonate I suppose but I'd rather just buy it,
>> plus that would include a dust cover.
>
> Why not just laser-cut down a 10.5" reel?  The hub dimensions are the same.
>
> --Chuck

Or take the reels to a engineering shop and ask them to turn them down on a 
lathe,
it should be a very simple job for them. Besides, there are lots of 10.5" dia 
tapes
available on eBay, and I'm sure I've seen sellers with 8" tape reels.

On my Kennedy 9000s the rubber O-rings have expanded on all the spindles and a
reel has a lot of trouble being pushed on and removed. I plan to replace them 
with
neoprene O-rings of the original size. These are readily available and cheap 
from
bearing supplies stores, I'll get a range of close sizes and find the right one.

Steve.

Re: HP 7970E - interest to split?

[Anders Nelson via cctalk]

Hi Chuck,

Yeah I could try that but unless I can separate the reel halves from the
hub I'd have to make a jig of sorts to absorb the laser beam on the bottom
side of the cut. Can the sides be separated? And is it possible to cut down
a dust cover?

=]

--
Anders Nelson

+1 (517) 775-6129

www.erogear.com

On Fri, Sep 29, 2017 at 12:12 AM, Chuck Guzis via cctalk <
cctalk@classiccmp.org> wrote:

> On 09/28/2017 08:57 PM, Anders Nelson via cctalk wrote:
> > Update: I bought the Kennedy 9800 as it pushed all my buttons at once.
> >
> > Now I'm looking for 8" mag tapes/reels that will fit! Anyone know where I
> > can find these, maybe 3pcs? I could laser-cut some frosted acrylic or
> > machine some frosted polycarbonate I suppose but I'd rather just buy it,
> > plus that would include a dust cover.
>
> Why not just laser-cut down a 10.5" reel?  The hub dimensions are the same.
>
> --Chuck
>
>

Re: HP 7970E - interest to split?

[Chuck Guzis via cctalk]

On 09/28/2017 08:57 PM, Anders Nelson via cctalk wrote:
> Update: I bought the Kennedy 9800 as it pushed all my buttons at once.
> 
> Now I'm looking for 8" mag tapes/reels that will fit! Anyone know where I
> can find these, maybe 3pcs? I could laser-cut some frosted acrylic or
> machine some frosted polycarbonate I suppose but I'd rather just buy it,
> plus that would include a dust cover.

Why not just laser-cut down a 10.5" reel?  The hub dimensions are the same.

--Chuck

Re: HP 7970E - interest to split?

[Anders Nelson via cctalk]

Update: I bought the Kennedy 9800 as it pushed all my buttons at once.

Now I'm looking for 8" mag tapes/reels that will fit! Anyone know where I
can find these, maybe 3pcs? I could laser-cut some frosted acrylic or
machine some frosted polycarbonate I suppose but I'd rather just buy it,
plus that would include a dust cover.

On a related note my plan is to make a USB-based, Pertec-compatible
controller for it. Not sure how SimH connects with peripherals so I'm
/very/ eager to talk with someone familiar with its workings. I'll also
release all the board files and firmware as open-source. Timeline as always
is completely unknown, though I do have a now-vested interest in making it
work.

Be well!

On Tue, Sep 26, 2017 at 10:42 PM Anders Nelson 
wrote:

> Well there goes my evening, thanks Chuck!
>
> --
> Anders Nelson
>
> +1 (517) 775-6129
>
> www.erogear.com
>
> On Tue, Sep 26, 2017 at 10:09 PM, Chuck Guzis via cctalk <
> cctalk@classiccmp.org> wrote:
>
>> On 09/26/2017 06:45 PM, Anders Nelson via cctalk wrote:
>> > Cool, is there documentation available for this formatting and
>> > error-check/correction algorithm and structure? I'd like to take a look!
>>
>> A good place to start is the HP "Introduction to Magnetic Tape" in
>> bitsavers:
>>
>>
>> http://bitsavers.informatik.uni-stuttgart.de/pdf/hp/tape/MVD-014_introToMagTap_Apr71.pdf
>>
>> --Chuck
>>
>>
> --
--
Anders Nelson
+1 (517) 775-6129
www.erogear.com

Re: HP 7970E - interest to split?

[Anders Nelson via cctalk]

Well there goes my evening, thanks Chuck!

--
Anders Nelson

+1 (517) 775-6129

www.erogear.com

On Tue, Sep 26, 2017 at 10:09 PM, Chuck Guzis via cctalk <
cctalk@classiccmp.org> wrote:

> On 09/26/2017 06:45 PM, Anders Nelson via cctalk wrote:
> > Cool, is there documentation available for this formatting and
> > error-check/correction algorithm and structure? I'd like to take a look!
>
> A good place to start is the HP "Introduction to Magnetic Tape" in
> bitsavers:
>
> http://bitsavers.informatik.uni-stuttgart.de/pdf/hp/tape/
> MVD-014_introToMagTap_Apr71.pdf
>
> --Chuck
>
>

Re: HP 7970E - interest to split?

[Chuck Guzis via cctalk]

On 09/26/2017 06:45 PM, Anders Nelson via cctalk wrote:
> Cool, is there documentation available for this formatting and
> error-check/correction algorithm and structure? I'd like to take a look!

A good place to start is the HP "Introduction to Magnetic Tape" in
bitsavers:

http://bitsavers.informatik.uni-stuttgart.de/pdf/hp/tape/MVD-014_introToMagTap_Apr71.pdf

--Chuck

Re: HP 7970E - interest to split?

[Anders Nelson via cctalk]

Cool, is there documentation available for this formatting and
error-check/correction algorithm and structure? I'd like to take a look!

=]

--
Anders Nelson

+1 (517) 775-6129

www.erogear.com

On Tue, Sep 26, 2017 at 12:26 PM, Chuck Guzis via cctalk <
cctalk@classiccmp.org> wrote:

> On 09/25/2017 11:40 PM, Steve Malikoff via cctalk wrote:
>
> > Yes, you will need the controller to at least format, but not sure about
> just reading/writing.
>
> Looking at the interface, it's pretty much a "raw" interface.
>
> As in a lot of things in life, timing is everything in tapes.Tape
> blocks are separated by blank gaps--it's the gap that defines the block
> boundaries.   In addition, check characters (LRCC in 7 track; CRC+LRCC
> in 9 track) are separated from block data by a specified number of bit
> times of empty space.
>
> External logic has to generate/check vertical and horizontal parity, and
> insert the required spacing between check characters and inter-block
> gaps.   In addition, most formatters will correct any single-bit errors
> in a block (using the vertical and horizontal parity(LRCC) to locate the
> bit in error).
>
> Logic should also include generation/detection of tapemarks.
>
> It's not simple, but it's also not rocket science.
>
> --Chuck
>
>
>
>

Re: HP 7970E - interest to split?

[Chuck Guzis via cctalk]

On 09/25/2017 11:40 PM, Steve Malikoff via cctalk wrote:

> Yes, you will need the controller to at least format, but not sure about just 
> reading/writing.

Looking at the interface, it's pretty much a "raw" interface.

As in a lot of things in life, timing is everything in tapes.Tape
blocks are separated by blank gaps--it's the gap that defines the block
boundaries.   In addition, check characters (LRCC in 7 track; CRC+LRCC
in 9 track) are separated from block data by a specified number of bit
times of empty space.

External logic has to generate/check vertical and horizontal parity, and
insert the required spacing between check characters and inter-block
gaps.   In addition, most formatters will correct any single-bit errors
in a block (using the vertical and horizontal parity(LRCC) to locate the
bit in error).

Logic should also include generation/detection of tapemarks.

It's not simple, but it's also not rocket science.

--Chuck

RE: HP 7970E - interest to split?

[Steve Malikoff via cctalk]

> Well, as others have pointed out, a "tape transport" is not the whole 
> ball-of-wax.  You need the ability to format the tape into blocks and then 
> control tape motion in terms of those blocks.  That's what you'd be 
> responsible for in your added electronics.  From the Introduction in the 
> Kennedy
manual:>
> "The Model 9800 is equipped with the electronics
> necessary for reading and writing tapes and for
> controlling the tape motion. The head specifications
> and the mechanical and electrical tolerances of the
> Model 9800 meet the requirements for IBM compatibility.
>
> However, the formatting electronics, parity
> generator, cyclic redundancy check character (CRCC)
> generator, gap control, etc, are not included and
> must be provided by the tape control and formatter
> in order to generate properly formatted IBM compatible
> tapes."

Yes, you will need the controller to at least format, but not sure about just 
reading/writing.
Earlier this year I lucked onto a pair of Kennedy 9000 drives from a listmember 
here in Oz. These are
similar in physical size and arrangement to the HP 97970 rather than the more 
compact 9800 on eBay. Not
long after, I found a Kennedy 9219 Format Control Unit formatter in the US 
which I shipped to Oz. I also
acquired an Emulex TC11 unibus controller and an Emulex TC03 Qbus controller 
but have not been able to find
the split ribbon cable yet. However I think this is the standard Pertec 
interface cable, so I will be posting
the boards to this listmember for testing sometime in the near future to find 
out whether the whole box and
dice will actually work together, at least for one of the controllers. I bought 
some 36-pin edge connectors in
anticipation of making up my own split cable based on the listmember's cable.
It's going to be a long while before I can report anything, but whatever 
happens I'll at least be making some
notes about it.

Steve.

Re: HP 7970E - interest to split?

[jim stephens via cctalk]

For generic drives of either 800 or 1600, there were Pertec formatters 
that drove the three cable Pertec interface (read / write / motion) and 
was compatible with the P1 P2 parallel formatted interface.


The ones I had were one format or another.  And they had to be strapped 
to the speed of the drive.  I am not sure if the ones I had which had 
one or 2 large boards would keep up with faster than 25ips drives.


They were about 5" high and mounted under the drive, with an option 
switch or two on them.  I did run them with a second tape unit daisy 
chained on the parallel formatted side.


There was no way to run more than a single 3 cable interface.  I've 
never heard of a way to accomplish that with any controller.


The parallel formatted Pertec has unit select, but each drive went to a 
unique connection.  Any drive could be used standalone, as there was no 
A unit / B type unit at all with the Pertec drives, anyway.


thanks
Jim

On 9/25/2017 11:02 PM, Paul Birkel via cctalk wrote:

Well, as others have pointed out, a "tape transport" is not the whole 
ball-of-wax.  You need the ability to format the tape into blocks and then control tape 
motion in terms of those blocks.  That's what you'd be responsible for in your added 
electronics.  From the Introduction in the Kennedy manual:

"The Model 9800 is equipped with the electronics
necessary for reading and writing tapes and for
controlling the tape motion. The head specifications
and the mechanical and electrical tolerances of the
Model 9800 meet the requirements for IBM compatibility.

However, the formatting electronics, parity
generator, cyclic redundancy check character (CRCC)
generator, gap control, etc, are not included and
must be provided by the tape control and formatter
in order to generate properly formatted IBM compatible
tapes."

-Original Message-
From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Anders Nelson 
via cctalk
Sent: Tuesday, September 26, 2017 1:41 AM
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: HP 7970E - interest to split?

Ah, yeah that's actually better for my purpose. I'm more concerned with the
data interface - can I just read and write bits at will or are there
contingencies as someone mentioned before?

=]

On Tue, Sep 26, 2017 at 12:06 AM Paul Birkel <pbir...@gmail.com> wrote:


-Original Message-
From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Anders
Nelson via cctalk
Sent: Monday, September 25, 2017 7:01 PM
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: HP 7970E - interest to split?

Hmmm, interesting. How does the 7970 compare to the Kennedy 9800?:


http://www.ebay.com/itm/Kennedy-9800-9-Track-Data-Tape-Subsystem/232493086636

For the same price the Kennedy drive looks more beautimous...

=]

--
Anders Nelson

-


http://bitsavers.trailing-edge.com/pdf/kennedy/Kennedy_9800_Digital_Tape_Transport_Operation_and_Maintenance_Manual.pdf

8.5" reels  (not the full size 10.5")


http://bitsavers.trailing-edge.com/pdf/hp/tape/7970/07970-90885_7970oper_Dec76.pdf

-

--

--
Anders Nelson
+1 (517) 775-6129
www.erogear.com

RE: HP 7970E - interest to split?

[Paul Birkel via cctalk]

Well, as others have pointed out, a "tape transport" is not the whole 
ball-of-wax.  You need the ability to format the tape into blocks and then 
control tape motion in terms of those blocks.  That's what you'd be responsible 
for in your added electronics.  From the Introduction in the Kennedy manual:

"The Model 9800 is equipped with the electronics
necessary for reading and writing tapes and for
controlling the tape motion. The head specifications
and the mechanical and electrical tolerances of the
Model 9800 meet the requirements for IBM compatibility.

However, the formatting electronics, parity
generator, cyclic redundancy check character (CRCC)
generator, gap control, etc, are not included and
must be provided by the tape control and formatter
in order to generate properly formatted IBM compatible
tapes."

-Original Message-
From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Anders Nelson 
via cctalk
Sent: Tuesday, September 26, 2017 1:41 AM
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: HP 7970E - interest to split?

Ah, yeah that's actually better for my purpose. I'm more concerned with the
data interface - can I just read and write bits at will or are there
contingencies as someone mentioned before?

=]

On Tue, Sep 26, 2017 at 12:06 AM Paul Birkel <pbir...@gmail.com> wrote:

> -Original Message-
> From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Anders
> Nelson via cctalk
> Sent: Monday, September 25, 2017 7:01 PM
> To: General Discussion: On-Topic and Off-Topic Posts
> Subject: Re: HP 7970E - interest to split?
>
> Hmmm, interesting. How does the 7970 compare to the Kennedy 9800?:
>
>
> http://www.ebay.com/itm/Kennedy-9800-9-Track-Data-Tape-Subsystem/232493086636
>
> For the same price the Kennedy drive looks more beautimous...
>
> =]
>
> --
> Anders Nelson
>
> -
>
>
> http://bitsavers.trailing-edge.com/pdf/kennedy/Kennedy_9800_Digital_Tape_Transport_Operation_and_Maintenance_Manual.pdf
>
> 8.5" reels  (not the full size 10.5")
>
>
> http://bitsavers.trailing-edge.com/pdf/hp/tape/7970/07970-90885_7970oper_Dec76.pdf
>
> -
>
> --
--
Anders Nelson
+1 (517) 775-6129
www.erogear.com

Re: HP 7970E - interest to split?

[Anders Nelson via cctalk]

Ah, yeah that's actually better for my purpose. I'm more concerned with the
data interface - can I just read and write bits at will or are there
contingencies as someone mentioned before?

=]

On Tue, Sep 26, 2017 at 12:06 AM Paul Birkel <pbir...@gmail.com> wrote:

> -Original Message-
> From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Anders
> Nelson via cctalk
> Sent: Monday, September 25, 2017 7:01 PM
> To: General Discussion: On-Topic and Off-Topic Posts
> Subject: Re: HP 7970E - interest to split?
>
> Hmmm, interesting. How does the 7970 compare to the Kennedy 9800?:
>
>
> http://www.ebay.com/itm/Kennedy-9800-9-Track-Data-Tape-Subsystem/232493086636
>
> For the same price the Kennedy drive looks more beautimous...
>
> =]
>
> --
> Anders Nelson
>
> -
>
>
> http://bitsavers.trailing-edge.com/pdf/kennedy/Kennedy_9800_Digital_Tape_Transport_Operation_and_Maintenance_Manual.pdf
>
> 8.5" reels  (not the full size 10.5")
>
>
> http://bitsavers.trailing-edge.com/pdf/hp/tape/7970/07970-90885_7970oper_Dec76.pdf
>
> -
>
> --
--
Anders Nelson
+1 (517) 775-6129
www.erogear.com

RE: HP 7970E - interest to split?

[Paul Birkel via cctalk]

-Original Message-
From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Anders Nelson 
via cctalk
Sent: Monday, September 25, 2017 7:01 PM
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: HP 7970E - interest to split?

Hmmm, interesting. How does the 7970 compare to the Kennedy 9800?:

http://www.ebay.com/itm/Kennedy-9800-9-Track-Data-Tape-Subsystem/232493086636

For the same price the Kennedy drive looks more beautimous...

=]

--
Anders Nelson

-

http://bitsavers.trailing-edge.com/pdf/kennedy/Kennedy_9800_Digital_Tape_Transport_Operation_and_Maintenance_Manual.pdf

8.5" reels  (not the full size 10.5")

http://bitsavers.trailing-edge.com/pdf/hp/tape/7970/07970-90885_7970oper_Dec76.pdf

-

Re: HP 7970E - interest to split?

[Anders Nelson via cctalk]

Hmmm, interesting. How does the 7970 compare to the Kennedy 9800?:

http://www.ebay.com/itm/Kennedy-9800-9-Track-Data-Tape-Subsystem/232493086636

For the same price the Kennedy drive looks more beautimous...

=]

--
Anders Nelson

+1 (517) 775-6129

www.erogear.com

On Mon, Sep 25, 2017 at 2:18 PM, Jay West via cctalk 
wrote:

> ED#WROTE
> What is really  scarce is a  7 track  7970b!
> 
> I have a 7970B (needs some repair) that I would LOVE to trade for a 7970E.
>
> J
>
>
>

RE: HP 7970E - interest to split?

[Jay West via cctalk]

ED#WROTE
What is really  scarce is a  7 track  7970b!

I have a 7970B (needs some repair) that I would LOVE to trade for a 7970E.

J

Re: HP 7970E - interest to split?

[Ed via cctalk]

What is really  scarce is a  7 track  7970b!
Had one once...  it was the first  used HP  item I ever sold  when I was in 
the used computer  biz  early 80s.
 Wish now  I had  kept it! 
Ed#
 
 
In a message dated 9/25/2017 10:26:10 A.M. US Mountain Standard Time,  
cctalk@classiccmp.org writes:

On  09/25/2017 08:27 AM, Anders Nelson via cctalk wrote:
> Cool! Aaa, good  to know one of them can't be used individually.
> 
> What might be  involved in using one with a PDP-8/e emulated on SimH? I 
can
>  build/program any sort of custom USB device to interface this big  stuff,
> which I'll open-source of course. But does it need special  power/startup
> stuff beyond a control interface to get it  working?

I can speak only for my experience with the 7970B, which is an  800 NRZI
model and has no "slave' mode. The distinguishing characteristic  on the
7970E between master and slave is that the slave does not contain  the
1600 PE read or write circuitry.

If you're accustomed to a  Pertec interface, then the 800 interface isn't
terribly different, just  dumber.  You still have a connector for the
basic motion and status  commands (i.e. forward, reverse, rewind,
high-speed and online, loadpoint,  ready, protect) and you have two
8-bit+parity clocked data channels for  read and write respectively, each
with their own connector.

However,  there is no formatter, as on Pertec interface drives.  You get
the  raw, framed and deskewed data on read and pretty much anything you
want to  put in on write.   No "handshaking" as the interfaces are  not
buffered.

Thanks to Al, I've just adapted a 7970B to used a  combination head stack
for 7 and 9 track tapes.   Some 7970Es  already come so equipped, but
they're not common.  I fabricated a  small PCB with 5 miniature DPDT
relays to do the switching and it fits  right under the head assembly,
with the B's 9-track read amplifier plugging  in as usual.

The lack of a formatter means that you'll have to do the  work of gap
detection, parity checking/generation and CRC/LRCC  interpretation and
generation yourself, as well as manage the control  lines.

I used a small STM32F407 MCU board (about $10) which has lots of  5V
tolerant I/O, so receiving data and status is no problem.  For  driving
control lines, simply set the GPIO pins for open-drain  operation.
There's something like 24ma of sinking capacity on those, so  again, no
need for intermediate logic.   Since I'm interested in  reading tapes,
but not writing them, I can't address the issue of what to  do about that
end.  My setup uses a serial port for interaction and a  USB port that
makes the onboard SDHC look like a generic storage  device.  So, read a
tape, dump the data into the SDHC (Chan's FATFS  software is useful);
suck it out via the USB port to a PeeSee.

To  handle 1600 PE data would require yet another layer of software.

I  realize that not many are interested in my peculiar needs, but perhaps
this  will go to answer a question or  two.

--Chuck

Re: HP 7970E - interest to split?

[Chuck Guzis via cctalk]

On 09/25/2017 08:27 AM, Anders Nelson via cctalk wrote:
> Cool! Aaa, good to know one of them can't be used individually.
> 
> What might be involved in using one with a PDP-8/e emulated on SimH? I can
> build/program any sort of custom USB device to interface this big stuff,
> which I'll open-source of course. But does it need special power/startup
> stuff beyond a control interface to get it working?

I can speak only for my experience with the 7970B, which is an 800 NRZI
model and has no "slave' mode. The distinguishing characteristic on the
7970E between master and slave is that the slave does not contain the
1600 PE read or write circuitry.

If you're accustomed to a Pertec interface, then the 800 interface isn't
terribly different, just dumber.  You still have a connector for the
basic motion and status commands (i.e. forward, reverse, rewind,
high-speed and online, loadpoint, ready, protect) and you have two
8-bit+parity clocked data channels for read and write respectively, each
with their own connector.

However, there is no formatter, as on Pertec interface drives.  You get
the raw, framed and deskewed data on read and pretty much anything you
want to put in on write.   No "handshaking" as the interfaces are not
buffered.

Thanks to Al, I've just adapted a 7970B to used a combination head stack
for 7 and 9 track tapes.   Some 7970Es already come so equipped, but
they're not common.  I fabricated a small PCB with 5 miniature DPDT
relays to do the switching and it fits right under the head assembly,
with the B's 9-track read amplifier plugging in as usual.

The lack of a formatter means that you'll have to do the work of gap
detection, parity checking/generation and CRC/LRCC interpretation and
generation yourself, as well as manage the control lines.

I used a small STM32F407 MCU board (about $10) which has lots of 5V
tolerant I/O, so receiving data and status is no problem.  For driving
control lines, simply set the GPIO pins for open-drain operation.
There's something like 24ma of sinking capacity on those, so again, no
need for intermediate logic.   Since I'm interested in reading tapes,
but not writing them, I can't address the issue of what to do about that
end.  My setup uses a serial port for interaction and a USB port that
makes the onboard SDHC look like a generic storage device.  So, read a
tape, dump the data into the SDHC (Chan's FATFS software is useful);
suck it out via the USB port to a PeeSee.

To handle 1600 PE data would require yet another layer of software.

I realize that not many are interested in my peculiar needs, but perhaps
this will go to answer a question or two.

--Chuck

Re: HP 7970E - interest to split?

[Robert via cctalk]

That sounds very plausible, Mike.

It's too far for me, but I bet somebody local could get both lots for
$1000, by picking them up and saving them the hassle of crating etc.
-- 
Robert

On Mon, Sep 25, 2017 at 12:07 PM, Mike Loewen via cctalk
 wrote:
> On Mon, 25 Sep 2017, Anders Nelson via cctalk wrote:
>
>> Hi there, here's an eBay auction for two HP 7970E tape drives that appear
>> to function:
>>
>>
>> http://www.ebay.com/itm/VINTAGE-HP-7970e-DUAL-Tape-Drive-Cabinet-Reel-to-Reel-Player-/192204691239
>>
>> I'm curious if anyone is looking for one of these drives. I'm not sure if
>> I
>> want to pull the trigger on something expensive I won't use until I have
>> free time, but I imagine stuff like this is only getting more rare. I have
>> a Remex paper tape reader in seemingly perfect condition I intend to use
>> with an emulated PDP-8/e (using Rod Smallwood's repro front panel), but
>> it'd be awesome to be able to save stuff too.
>
>
>I believe these drives were originally attached to the 2117F in this
> auction:
>
> Ebay 401311487499
>
>I zoomed in on the first photo and it appears that the upper drive is a
> 7970E and the lower is a 7970B.  The tape controller board sets in their
> 2117F are 13183 (7970E) and 13181 (7970B), which is why I think these two
> items belong together.  The 7970B was nominally 800bpi NRZI, while the 7970E
> was 1600bpi PE.  However, each drive had options, so it's impossible to say
> what capabilities are there without seeing the option numbers.
>
>If someone wanted to pick up both items, you'd have a nice setup.
>
>
> Mike Loewen mloe...@cpumagic.scol.pa.us
> Old Technology  http://q7.neurotica.com/Oldtech/

Re: HP 7970E - interest to split?

[Mike Loewen via cctalk]

On Mon, 25 Sep 2017, Anders Nelson via cctalk wrote:


Hi there, here's an eBay auction for two HP 7970E tape drives that appear
to function:

http://www.ebay.com/itm/VINTAGE-HP-7970e-DUAL-Tape-Drive-Cabinet-Reel-to-Reel-Player-/192204691239

I'm curious if anyone is looking for one of these drives. I'm not sure if I
want to pull the trigger on something expensive I won't use until I have
free time, but I imagine stuff like this is only getting more rare. I have
a Remex paper tape reader in seemingly perfect condition I intend to use
with an emulated PDP-8/e (using Rod Smallwood's repro front panel), but
it'd be awesome to be able to save stuff too.


   I believe these drives were originally attached to the 2117F in this 
auction:


Ebay 401311487499

   I zoomed in on the first photo and it appears that the upper drive is a 
7970E and the lower is a 7970B.  The tape controller board sets in their 
2117F are 13183 (7970E) and 13181 (7970B), which is why I think these two 
items belong together.  The 7970B was nominally 800bpi NRZI, while the 
7970E was 1600bpi PE.  However, each drive had options, so it's impossible 
to say what capabilities are there without seeing the option numbers.


   If someone wanted to pick up both items, you'd have a nice setup.


Mike Loewen mloe...@cpumagic.scol.pa.us
Old Technology  http://q7.neurotica.com/Oldtech/

Re: HP 7970E - interest to split?

[Anders Nelson via cctalk]

Cool! Aaa, good to know one of them can't be used individually.

What might be involved in using one with a PDP-8/e emulated on SimH? I can
build/program any sort of custom USB device to interface this big stuff,
which I'll open-source of course. But does it need special power/startup
stuff beyond a control interface to get it working?

=]

--
Anders Nelson

+1 (517) 775-6129

www.erogear.com

On Mon, Sep 25, 2017 at 11:02 AM, Jay West  wrote:

> I may be convinced to split it with you. I could always use another 7970E.
> I can't tell from the pictures if one is master and one is slave only
> though.. that would be key.
>
>
>
>

RE: HP 7970E - interest to split?

[Jay West via cctalk]

I may be convinced to split it with you. I could always use another 7970E. I 
can't tell from the pictures if one is master and one is slave only 
though.. that would be key.