26 Feb
2013
26 Feb
'13
10:31 a.m.
Hi folks,
I'd like to introduce my newly designed Omnibus-USB interface.
I designed a quite well working prototype of something that looks like a KL8E
for the PDP8 and like a serial port on the PC - but is none of both :-)
It ist not meant as a console terminal replacement (which it could be used as)
but as an alternative IO device used to dump (archive!) and restore mass storage
media.
To the people who don't know the problems of having MASSES of disks and tapes to
dump: Please don't flame.
Pictures and some more information can be found on my website:
http://pdp8.hachti.de?gallery/omnibus_usb
My intention is to design an improved (probably full height) version and do a
little production run. As I'm currently out of work, selling those boards could
help a bit. I can do it only if I get enough preorders. So I ask everybody with
serious interest to tell me how many boards he wants and how much he could
spend. Based on that feedback I'll decide if I can do it and fix a price. It
won't be cheap - but very helpful and cool!
I'd really like to make some more. It would be great if there's enough interest
to do it.
If you have any suggestions, let me know!
Kind regards,
Philipp :-)
--
Dipl.-Inf. (FH) Philipp Hachtmann
Buchdruck, Bleisatz, Spezialit?ten
Alemannstr. 21, D-30165 Hannover
Tel. 0511/3522222, Mobil 0171/2632239
Fax. 0511/3500439
hachti at hachti.de
www.tiegeldruck.de
UStdID DE 202668329
26 Feb
26 Feb
10:34 a.m.
how much?????????
On Tue, Feb 26, 2013 at 12:31 PM, Philipp Hachtmann <hachti at hachti.de>wrote:
Hi folks,
I'd like to introduce my newly designed Omnibus-USB interface.
I designed a quite well working prototype of something that looks like a
KL8E for the PDP8 and like a serial port on the PC - but is none of both :-)
It ist not meant as a console terminal replacement (which it could be used
as) but as an alternative IO device used to dump (archive!) and restore
mass storage media.
To the people who don't know the problems of having MASSES of disks and
tapes to dump: Please don't flame.
Pictures and some more information can be found on my website:
http://pdp8.hachti.de?gallery/**omnibus_usb<http://pdp8.hachti.de?galler…
My intention is to design an improved (probably full height) version and
do a little production run. As I'm currently out of work, selling those
boards could help a bit. I can do it only if I get enough preorders. So I
ask everybody with serious interest to tell me how many boards he wants and
how much he could spend. Based on that feedback I'll decide if I can do it
and fix a price. It won't be cheap - but very helpful and cool!
I'd really like to make some more. It would be great if there's enough
interest to do it.
If you have any suggestions, let me know!
Kind regards,
Philipp :-)
--
Dipl.-Inf. (FH) Philipp Hachtmann
Buchdruck, Bleisatz, Spezialit?ten
Alemannstr. 21, D-30165 Hannover
Tel. 0511/3522222, Mobil 0171/2632239
Fax. 0511/3500439
hachti at hachti.de
www.tiegeldruck.de
UStdID DE 202668329
3:34 p.m.
Am 26.02.2013 19:34, schrieb Adrian Stoness:
how much?????????
Depends on interest/lot size.
After 3 hours now the price is at approx.
EUR 250/piece without VAT - falling with growing number of boards.
But it should still become cheaper....
On Tue, Feb 26, 2013 at 12:31 PM, Philipp Hachtmann<hachti at hachti.de>wrote:
> Hi folks,
>
> I'd like to introduce my newly designed Omnibus-USB interface.
> I designed a quite well working prototype of something that looks like a
> KL8E for the PDP8 and like a serial port on the PC - but is none of both :-)
>
> It ist not meant as a console terminal replacement (which it could be used
> as) but as an alternative IO device used to dump (archive!) and restore
> mass storage media.
> To the people who don't know the problems of having MASSES of disks and
> tapes to dump: Please don't flame.
>
> Pictures and some more information can be found on my website:
>
http://pdp8.hachti.de?gallery/**omnibus_usb<http://pdp8.hachti.de?galler…
>
> My intention is to design an improved (probably full height) version and
> do a little production run. As I'm currently out of work, selling those
> boards could help a bit. I can do it only if I get enough preorders. So I
> ask everybody with serious interest to tell me how many boards he wants and
> how much he could spend. Based on that feedback I'll decide if I can do it
> and fix a price. It won't be cheap - but very helpful and cool!
>
> I'd really like to make some more. It would be great if there's enough
> interest to do it.
>
> If you have any suggestions, let me know!
>
>
> Kind regards,
>
> Philipp :-)
>
> --
>
>
> Dipl.-Inf. (FH) Philipp Hachtmann
> Buchdruck, Bleisatz, Spezialit?ten
>
> Alemannstr. 21, D-30165 Hannover
> Tel. 0511/3522222, Mobil 0171/2632239
> Fax. 0511/3500439
> hachti at hachti.de
> www.tiegeldruck.de
>
> UStdID DE 202668329
>
3:03 p.m.
I should point out that (at least from looking at a couple of the photos) you're not
using Unibus transceivers which are standard on Omnibus devices. It'll probably work
OK on a lightly loaded system but a PDP-8/e with a double backplane with lots of boards
may have issues.
TTFN - Guy
On Feb 26, 2013, at 3:34 PM, Philipp Hachtmann wrote:
Am 26.02.2013 19:34, schrieb Adrian Stoness:
how much?????????
Depends on interest/lot
size. After 3 hours now the price is at approx. EUR 250/piece without VAT - falling with
growing number of boards.
But it should still become cheaper....
On Tue, Feb 26, 2013 at 12:31 PM, Philipp Hachtmann<hachti at hachti.de>wrote:
> Hi folks,
>
> I'd like to introduce my newly designed Omnibus-USB interface.
> I designed a quite well working prototype of something that looks like a
> KL8E for the PDP8 and like a serial port on the PC - but is none of both :-)
>
> It ist not meant as a console terminal replacement (which it could be used
> as) but as an alternative IO device used to dump (archive!) and restore
> mass storage media.
> To the people who don't know the problems of having MASSES of disks and
> tapes to dump: Please don't flame.
>
> Pictures and some more information can be found on my website:
>
http://pdp8.hachti.de?gallery/**omnibus_usb<http://pdp8.hachti.de?galler…
>
> My intention is to design an improved (probably full height) version and
> do a little production run. As I'm currently out of work, selling those
> boards could help a bit. I can do it only if I get enough preorders. So I
> ask everybody with serious interest to tell me how many boards he wants and
> how much he could spend. Based on that feedback I'll decide if I can do it
> and fix a price. It won't be cheap - but very helpful and cool!
>
> I'd really like to make some more. It would be great if there's enough
> interest to do it.
>
> If you have any suggestions, let me know!
>
>
> Kind regards,
>
> Philipp :-)
>
> --
>
>
> Dipl.-Inf. (FH) Philipp Hachtmann
> Buchdruck, Bleisatz, Spezialit?ten
>
> Alemannstr. 21, D-30165 Hannover
> Tel. 0511/3522222, Mobil 0171/2632239
> Fax. 0511/3500439
> hachti at hachti.de
> www.tiegeldruck.de
>
> UStdID DE 202668329
>
27 Feb
27 Feb
12:41 a.m.
Am 27.02.2013 00:03, schrieb Guy Sotomayor:
I should point out that (at least from looking at a
couple of the
photos) you're not using Unibus transceivers which are standard on
Omnibus devices. It'll probably work OK on a lightly loaded system
but a PDP-8/e with a double backplane with lots of boards may have
issues.
Ah, really? Of course NOT! The original driver was DEC8881 which is a
relabelled 7439. The 7438 I used has very similar specifications.
As the DEC8881 and the 7438 are not available, I have chosen the 7438.
And it does not make a big difference if the machine is more or less
loaded. The load on the drivers is always the same. It's an open
collector bus.
TTFN - Guy
On Feb 26, 2013, at 3:34 PM, Philipp Hachtmann wrote:
> Am 26.02.2013 19:34, schrieb Adrian Stoness:
>> how much?????????
> Depends on interest/lot size. After 3 hours now the price is at
> approx. EUR 250/piece without VAT - falling with growing number of
> boards. But it should still become cheaper....
>
>
>
>>
>> On Tue, Feb 26, 2013 at 12:31 PM, Philipp
>> Hachtmann<hachti at hachti.de>wrote:
>>
>>> Hi folks,
>>>
>>> I'd like to introduce my newly designed Omnibus-USB interface.
>>> I designed a quite well working prototype of something that
>>> looks like a KL8E for the PDP8 and like a serial port on the PC
>>> - but is none of both :-)
>>>
>>> It ist not meant as a console terminal replacement (which it
>>> could be used as) but as an alternative IO device used to dump
>>> (archive!) and restore mass storage media. To the people who
>>> don't know the problems of having MASSES of disks and tapes to
>>> dump: Please don't flame.
>>>
>>> Pictures and some more information can be found on my website:
>>>
http://pdp8.hachti.de?gallery/**omnibus_usb<http://pdp8.hachti.de?galler…
>>>
>>>
>>>
My intention is to design an improved (probably full height) version
and
> do a little production run. As I'm currently
out of work,
> selling those boards could help a bit. I can do it only if I
> get enough preorders. So I ask everybody with serious interest
> to tell me how many boards he wants and how much he could
> spend. Based on that feedback I'll decide if I can do it and
> fix a price. It won't be cheap - but very helpful and cool!
>
> I'd really like to make some more. It would be great if there's
> enough interest to do it.
>
> If you have any suggestions, let me know!
>
>
> Kind regards,
>
> Philipp :-)
>
> --
>
>
> Dipl.-Inf. (FH) Philipp Hachtmann Buchdruck, Bleisatz,
> Spezialit?ten
>
> Alemannstr. 21, D-30165 Hannover Tel. 0511/3522222, Mobil
> 0171/2632239 Fax. 0511/3500439 hachti at hachti.de
> www.tiegeldruck.de
>
> UStdID DE 202668329
>
1:10 a.m.
Guy Sotomayor wrote:
I should point out that (at least from looking at a
couple of the
photos) you're not using Unibus transceivers which are standard on
Omnibus devices. It'll probably work OK on a lightly loaded system
but a PDP-8/e with a double backplane with lots of boards may have
issues.
Philipp Hachtmann wrote:
Ah, really? Of course NOT! The original driver was
DEC8881 which is a
relabelled 7439.
I think it must have been more than just relablled; the original 8881
was from a non-7400 Signetics family whose name escapes me at the
moment, and may have been binned. The characteristics were somewhat
similar to the 7439 but not identical. The edge rate and maximum
leakage current are different. They may have binned 7439 parts that met
the Omnibus specs, but there's no expectation that an ordinary 7439 (or
7438) would.
The 7438 I used has very similar specifications.
As the DEC8881 and the 7438 are not available, I have chosen the 7438.
And it does not make a big difference if the machine is more or less
loaded. The load on the drivers is always the same. It's an open
collector bus.
The load isn't the same. Unlike modern CMOS parts, the receiver inputs
are not especially high-impedance. The receivers do present both DC and
AC loading on the bus lines. More receivers presents more loading. The
AC loading is often more of an issue than the DC.
The bigger problem with using parts that don't meet the DEC specs in
heavily loaded systems (Omnibus, Qbus, or Unibus, all of which are
similar electrically) is the receiver thresholds and the leakage
current. In large systems (multiple backplanes, or in the case of
Omnibus, even a full single 20-slot backplane), third-party modules that
used receivers with the wrong threshold (including all normal TTL parts)
do NOT work reliably, because in a heavily loaded bus asserted signals
don't always dip as low as the threshold of normal TTL parts, or don't
do so in a timely manner. This can easily be observed on such a system
using a 100 Mhz or better oscilliscope (with a slower scope you won't
see accurate signal edge waveforms).
On a lightly loaded system you can get away with using ordinary TTL
receivers and OC buffers.
5:02 a.m.
Philipp Hachtmann wrote:
Might be. As I remember the Signetics TTLs had different pinouts compared
to the
TI 74xx series. And now compare the 7438 and the 7439's pinouts: The 7439
doesn't only have a better drive performance (60mA) than the 7438 - its gates
are also in the "Signetics order". I have seen 7439 on a DEC board. Soldered
where other boards have 8881.
Ah, really? Of course NOT! The original driver
was DEC8881 which is a
relabelled 7439.
I think it must have been more than just relablled; the original 8881 was from a
non-7400 Signetics family whose name escapes me at the moment, and may have been
binned. The characteristics were somewhat similar to the 7439
but not identical.
The edge rate and maximum leakage current are different. They may have binned
7439 parts that met the Omnibus specs, but there's no expectation that an
ordinary 7439 (or 7438) would.
That discussion is a completely theoretical thing. Let's fix some facts:
- I have built working hardware
- I use the "wrong" drivers.
- The real drivers are not available anymore.
===>> I find it's a good compromise to use the 7438 as a replacement.
I could easily change the design to use real 8881 drivers. For me it would be
fine - I still have some of them. But I want to supply the board to other people
who might not have those chips. I want to use current hardware for that current
project.
The spare 8881 should be kept for repairs on old hardware.
And by the way I'm always open to suggestions for improvements. But only
complaining is not exactly that productive.
The 7438 I used has very similar specifications.
As the DEC8881 and the 7438 are not available, I have chosen the 7438.
And it does not make a big difference if the machine is more or less loaded.
The load on the drivers is always the same. It's an open collector bus.
The load isn't the same. Unlike modern CMOS parts, the receiver inputs are not
especially high-impedance. The receivers do present both DC and AC loading on
the bus lines. More receivers presents more loading. The AC loading is often
more of an issue than the DC. do NOT work
reliably, because in a heavily loaded bus asserted
signals don't always dip as
low as the threshold of normal TTL parts, or don't
do so in a timely manner.
On a lightly loaded system you can get away with using ordinary TTL receivers
and OC buffers.
11:24 a.m.
On Feb 27, 2013, at 12:41 AM, Philipp Hachtmann wrote:
Am 27.02.2013 00:03, schrieb Guy Sotomayor:
The 8881 is *not* a relabeled 7439. Yes, it's open collector but the current sinking
capabilities are pretty high (80ma?). It's also what's called a
"trapezoidal" driver which has a controlled slew rate (rise/fall times) to
minimize reflections on the bus. The drivers are optimized to drive into a bus terminated
by a 180ohm resistor to +5 and a 390ohm resistor to ground.
The receivers are also specialized and are not quite at the "standard" TTL
levels for greater noise immunity and minimal input leakage.
The Unibus interface chips (that were also used on Omnibus) are:
DS8640 quad bus receivers
DS8641 quad bus transceivers
DS8837 hex bus receivers
DS8881 quad bus drivers
There were older versions but these are pretty much what everyone used for Unibus and
Omnibus systems.
As I said, you can probably get away with it for small configurations but I would expect
some issues with larger systems/configurations.
TTFN - Guy
I should point out that (at least from looking at
a couple of the
photos) you're not using Unibus transceivers which are standard on
Omnibus devices. It'll probably work OK on a lightly loaded system
but a PDP-8/e with a double backplane with lots of boards may have
issues.
Ah, really? Of course NOT! The original driver was DEC8881 which is a
relabelled 7439. The 7438 I used has very similar specifications.
As the DEC8881 and the 7438 are not available, I have chosen the 7438.
And it does not make a big difference if the machine is more or less loaded. The load on
the drivers is always the same. It's an open collector bus. 
11:57 a.m.
On Feb 27, 2013, at 2:24 PM, Guy Sotomayor <ggs at shiresoft.com> wrote:
On Feb 27, 2013, at 12:41 AM, Philipp Hachtmann
wrote:
I'm not sure any but the last National Semiconductor transceivers
were actual trapezoidal drivers. That requires an integrator on
the output driver. My impression from the datasheets of the
earlier DEC chips is that they're binned for a particular max
slew rate, which is really all you need. By the time the true
trapezoidal transceivers came out (like the DS3662), the silicon
was both cheaper and faster, necessitating the rate limiting.
The current sink is also designated to be a maximum of 70mA by
DEC standards, but this is presumably a momentary sink for
driving the bus load capacitance low; the maximum sustained
current would be about 28mA (5v / 180 ohms) plus the relatively
small amount contributed by driver/receiver leakages (another
few mA if all the other bus participants are following the same
rules). There are also rules about the minimum voltage when
driving zero at 70mA, which many modern FETs meet quite handily.
There are a lot of discrete or paired FETs that should do the job
of the driver quite adequately; the receiver is usually best done
with a high-speed comparator, which unfortunately tend not to be
particularly cheap. The best one I've found for modern devices
is the MAX9108, which fits the required 35ns propagation delay;
it has TTL outputs (not great for 3.3v logic, but you can use
glue) and costs about $1 per gate ($.50 per in >= 100 qty).
That's what I have planned for my QBUS board, whenever it may
happen. If anyone happens to find a suitable comparator that
is cheaper, I'm all ears (don't forget about input leakage and
capacitance constraints!).
Ah, really? Of course NOT! The original driver
was DEC8881 which is a relabelled 7439. The 7438 I used has very similar specifications.
As the DEC8881 and the 7438 are not available, I have chosen the 7438.
And it does not make a big difference if the machine is more or less loaded. The load on
the drivers is always the same. It's an open collector bus.
The 8881 is *not* a relabeled 7439. Yes, it's open collector but the current sinking
capabilities are pretty high (80ma?). It's also what's called a
"trapezoidal" driver which has a controlled slew rate (rise/fall times) to
minimize reflections on the bus. The drivers are optimized to drive into a bus terminated
by a 180ohm resistor to +5 and a 390ohm resistor to ground. The receivers are also specialized and are not quite
at the "standard" TTL levels for greater noise immunity and minimal input
leakage.
The Unibus interface chips (that were also used on Omnibus) are:
DS8640 quad bus receivers
DS8641 quad bus transceivers
DS8837 hex bus receivers
DS8881 quad bus drivers
There were older versions but these are pretty much what everyone used for Unibus and
Omnibus systems.
There are newer ones as well, with true trapezoidal drivers, such
as the DS3662 (I think John Wilson said he had a large quantity
of some member of that family that he was happy to sell). None,
of course, are in production anymore.
- Dave
2:06 p.m.
Am 27.02.2013 20:57, schrieb David Riley:
There are a lot of discrete or paired FETs that should
do the job of the
driver quite adequately;
I had that idea, too. Even easier to design and -
cheaper.
the receiver is usually best done with a high-speed
comparator, which unfortunately tend not to be particularly cheap. The best
one I've found for modern devices is the MAX9108, which fits the required
35ns propagation delay;
35ns is not that fast. But it could work.
it has TTL outputs (not great for 3.3v logic, but you
can use glue) and costs about $1 per gate ($.50 per in>= 100 qty).
The CPLD
I'm planning to use (the three small ones are result of an "accident"
when estimating the pin consumption) is 5V tolerant.
I will keep the current design for now. After building a prototype of the final
board, I'll simply test it in a really loaded 8/e. And then we'll see if there
are reliability issues. I'll also test the system with the card in place.
Philipp
--
Dipl.-Inf. (FH) Philipp Hachtmann
Buchdruck, Bleisatz, Spezialit?ten
Alemannstr. 21, D-30165 Hannover
Tel. 0511/3522222, Mobil 0171/2632239
Fax. 0511/3500439
hachti at hachti.de
www.tiegeldruck.de
UStdID DE 202668329
2:55 p.m.
On Feb 27, 2013, at 5:06 PM, Philipp Hachtmann wrote:
35ns is the maximum propagation delay for drivers and receivers
per DEC specs (at least for QBUS and Unibus, so I'd assume any
bus standard which uses DEC transceivers). That's for the whole
chain, so it includes the receiver as well as any buffering
required after it. The MAX9108 has a typical Tpd of 25ns, but
the max isn't specified, which makes me a little uncomfortable.
I'm considering going with the LT1720/1721 (dual and quad of
the same comparator) which have a worst-case Tpd of under 10ns
with the kind of overdrive we're talking about. It also has
the advantage of running at 3.3v CMOS levels, which makes the
design a lot easier if you're talking to modern components. It
does cost about three times as much, though, which isn't great.
It'll generally work fine because most CPLDs these days are
designed to work with PCI, so they have 4.0v-capable pins
with clamp diodes to Vcc, so all you need to do is provide
series terms. Very handy, especially considering that TTL
generally only outputs about 3.4ish volts for a high value.
It all still makes me a bit nervous, but that's probably
unfounded worries.
Am 27.02.2013 20:57, schrieb David Riley:
It does come at the expense of some board space compared to an
integrated transceiver, though with modern SMT devices, not much.
If you're not doing the assembly yourself, that'll cost you as
well. For
There are a lot of discrete or paired FETs that
should do the job of the
driver quite adequately;
I had that idea, too. Even easier to design and -
cheaper. the receiver is usually best done with a
high-speed
comparator, which unfortunately tend not to be particularly cheap. The best
one I've found for modern devices is the MAX9108, which fits the required
35ns propagation delay;
35ns is not that fast. But it could work. it has TTL
outputs (not great for 3.3v logic, but you
can use glue) and costs about $1 per gate ($.50 per in>= 100 qty).
The CPLD
I'm planning to use (the three small ones are result of an "accident" when
estimating the pin consumption) is 5V tolerant. I will keep the current design for now. After building
a prototype of the final board, I'll simply test it in a really loaded 8/e. And then
we'll see if there are reliability issues. I'll also test the system with the card
in place.
If you can, can you get scope traces of your inputs and
outputs? I'm curious to see what they look like, since I
haven't built up my board yet (and I only have a 4-slot
backplane with which to test anyway). As Eric mentioned,
you'd probably want to do it on a 100 MHz bandwidth or
better scope.
Looks like it should be a winner, though! Great work!
- Dave
3:37 p.m.
Am 27.02.2013 23:55, schrieb David Riley:
If you're not doing the assembly yourself,
that'll cost you as
well.
Currently: hand soldering...
If you can, can you get scope traces of your inputs
and
outputs?
...
you'd probably want to do it on a 100 MHz bandwidth or
better scope.
I don't have such an oscilloscope. All I have is an old broken
10MHz phosphor
oscilloscope. On that the traces look great... A good digital storage
oscilloscope is one of the next thing that I have to earn with my designs :-)
Currently completely out of reach.
Philipp
--
Dipl.-Inf. (FH) Philipp Hachtmann
Buchdruck, Bleisatz, Spezialit?ten
Alemannstr. 21, D-30165 Hannover
Tel. 0511/3522222, Mobil 0171/2632239
Fax. 0511/3500439
hachti at hachti.de
www.tiegeldruck.de
UStdID DE 202668329
28 Feb
28 Feb
5:39 a.m.
On Feb 27, 2013, at 6:37 PM, Philipp Hachtmann <hachti at hachti.de> wrote:
Am 27.02.2013 23:55, schrieb David Riley:
Ah, well. I'll take some traces of mine under various conditions
once it's actually built up, whenever that is.
FWIW, I have a non-storage 100MHz analog oscilloscope that's good
enough for plenty of things that I got relatively cheaply off
eBay about 10 years ago. I don't know what the market for '80s
vintage Tek scopes is in Germany, but they're usually in the 50-
100 USD range over here. I'd love a decent digital scope, but
until I can afford something really nice, I'll stick with what
I've got.
- Dave
If you're not doing the assembly yourself,
that'll cost you as
well.
Currently: hand soldering...
If you can, can you get scope traces of your
inputs and
outputs?
...
you'd probably want to do it on a 100 MHz bandwidth or
better scope.
I don't have such an oscilloscope. All I have is an old broken
10MHz phosphor oscilloscope. On that the traces look great... A good digital storage
oscilloscope is one of the next thing that I have to earn with my designs :-)
Currently completely out of reach.
27 Feb
27 Feb
1:57 p.m.
Am 27.02.2013 20:24, schrieb Guy Sotomayor:
The 8881 is *not* a relabeled 7439.
Whatever it
is: I have *seen* that on an actual board.
--
Dipl.-Inf. (FH) Philipp Hachtmann
Buchdruck, Bleisatz, Spezialit?ten
Alemannstr. 21, D-30165 Hannover
Tel. 0511/3522222, Mobil 0171/2632239
Fax. 0511/3500439
hachti at hachti.de
www.tiegeldruck.de
UStdID DE 202668329
1:59 p.m.
The Omnibus drivers, at least on most 8/E-vingtage cards, were Signetics N8881, which were
not trapezoidal. I have Omnibus cards in my possession that have clearly-labelled TI 7439
parts used instead of the 8881. Early Omnibus cards used selected 7401s. The DS series
parts were used on Unibus and later-production Omnibus cards. Undoubtedly, they were
preferable once they became available. Likewise, the Schmitt-trigger receivers that
replaced the Signetics Utilogic II (SP380, etc.) parts. DEC used different solutions over
the years, some probably better-behaved electrically than others.
--Bill
--- On Wed, 2/27/13, Guy Sotomayor <ggs at shiresoft.com> wrote:
From: Guy Sotomayor <ggs at shiresoft.com>
Subject: Re: PDP8 Omnibus to USB interface
To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at
classiccmp.org>
Date: Wednesday, February 27, 2013, 11:24 AM
On Feb 27, 2013, at 12:41 AM, Philipp Hachtmann wrote:
DEC8881 which is a
relabelled 7439. The 7438 I used has very
similar specifications.
Am 27.02.2013 00:03, schrieb Guy Sotomayor:
> I should point out that (at least from looking at a
couple of the
> photos) you're not using Unibus
transceivers which
are standard on
> Omnibus devices.? It'll probably work OK
on a
lightly loaded system
> but a PDP-8/e with a double backplane with
lots of
boards may have
issues.
Ah, really? Of course NOT! The original driver was As the DEC8881 and the 7438 are not available, I
have
chosen the 7438.
And it does not make a big difference if the
machine is
more or less loaded. The load on the drivers is always the
same. It's an open collector bus.
The 8881 is *not* a relabeled 7439.? Yes, it's open
collector but the current sinking capabilities are pretty
high (80ma?).? It's also what's called a "trapezoidal"
driver which has a controlled slew rate (rise/fall times) to
minimize reflections on the bus.? The drivers are
optimized to drive into a bus terminated by a 180ohm
resistor to +5 and a 390ohm resistor to ground.
The receivers are also specialized and are not quite at the
"standard" TTL levels for greater noise immunity and minimal
input leakage.
The Unibus interface chips (that were also used on Omnibus)
are:
DS8640??? ??? quad bus
receivers
DS8641??? ??? quad bus
transceivers
DS8837??? ??? hex bus
receivers
DS8881??? ??? quad bus
drivers
There were older versions but these are pretty much what
everyone used for Unibus and Omnibus systems.
As I said, you can probably get away with it for small
configurations but I would expect some issues with larger
systems/configurations.
TTFN - Guy
26 Feb
26 Feb
3:15 p.m.
On Tue, Feb 26, 2013 at 6:34 PM, Philipp Hachtmann <hachti at hachti.de> wrote:
Depends on interest/lot size. After 3 hours now the
price is at approx. EUR
250/piece without VAT - falling with growing number of boards.
But it should still become cheaper....
I know this can be a touchy subject with folks that just want to make
one thing and not have an explosion of similar but different purchase
options, but I usually ask if it's possible to get just a bare board.
I can't afford to spend EUR 250 on anything PDP-8 related right now,
but if I could get a bare board for a fraction of that and solder my
own, I'd seriously consider it.
It's likely that there is not enough interest in a board-only option
to make it a viable option (especially if you are planning on having
the run assembled somewhere), but I thought I would ask.
-ethan
4:26 p.m.
On 02/26/2013 06:15 PM, Ethan Dicks wrote:
On Tue, Feb 26, 2013 at 6:34 PM, Philipp Hachtmann
<hachti at hachti.de> wrote:
+1 (qty. 2)
--
Dave McGuire, AK4HZ
New Kensington, PA
Depends on interest/lot size. After 3 hours now
the price is at approx. EUR
250/piece without VAT - falling with growing number of boards.
But it should still become cheaper....
I know this can be a touchy subject with folks that just want to make
one thing and not have an explosion of similar but different purchase
options, but I usually ask if it's possible to get just a bare board.
I can't afford to spend EUR 250 on anything PDP-8 related right now,
but if I could get a bare board for a fraction of that and solder my
own, I'd seriously consider it.
It's likely that there is not enough interest in a board-only option
to make it a viable option (especially if you are planning on having
the run assembled somewhere), but I thought I would ask.
27 Feb
27 Feb
12:48 a.m.
Hi Ethan,
I know this can be a touchy subject with folks that
just want to make
one thing and not have an explosion of similar but different purchase
options, but I usually ask if it's possible to get just a bare board.
The board
and its design are the expensive parts. Not the labor.
I can't afford to spend EUR 250 on anything PDP-8
related right now,
Like me...
but if I could get a bare board for a fraction of that
and solder my
own, I'd seriously consider it.
Impossible for a fraction.
I have calculated a bit. EUR 100-120 for the whole device will be
possible if I see a perspective to sell 20-25 pieces over time with half
of them preordered.
Kind regards
Philipp
26 Feb
26 Feb
9:47 p.m.
whats vat?
On Tue, Feb 26, 2013 at 5:34 PM, Philipp Hachtmann <hachti at hachti.de> wrote:
Am 26.02.2013 19:34, schrieb Adrian Stoness:
how much?????????
Depends on interest/lot size. After 3 hours now the price is at approx.
EUR 250/piece without VAT - falling with growing number of boards.
But it should still become cheaper....
On Tue, Feb 26, 2013 at 12:31 PM, Philipp
Hachtmann<hachti at hachti.de>**
wrote:
Hi folks,
>
> I'd like to introduce my newly designed Omnibus-USB interface.
> I designed a quite well working prototype of something that looks like a
> KL8E for the PDP8 and like a serial port on the PC - but is none of both
> :-)
>
> It ist not meant as a console terminal replacement (which it could be
> used
> as) but as an alternative IO device used to dump (archive!) and restore
> mass storage media.
> To the people who don't know the problems of having MASSES of disks and
> tapes to dump: Please don't flame.
>
> Pictures and some more information can be found on my website:
>
http://pdp8.hachti.de?gallery/****omnibus_usb<http://pdp8.hachti.de?gall…
>
<http://pdp8.**hachti.de?gallery/omnibus_usb<http://pdp8.hachti.de?gallery/omnibus_usb>
> >
>
>
> My intention is to design an improved (probably full height) version and
> do a little production run. As I'm currently out of work, selling those
> boards could help a bit. I can do it only if I get enough preorders. So I
> ask everybody with serious interest to tell me how many boards he wants
> and
> how much he could spend. Based on that feedback I'll decide if I can do
> it
> and fix a price. It won't be cheap - but very helpful and cool!
>
> I'd really like to make some more. It would be great if there's enough
> interest to do it.
>
> If you have any suggestions, let me know!
>
>
> Kind regards,
>
> Philipp :-)
>
> --
>
>
> Dipl.-Inf. (FH) Philipp Hachtmann
> Buchdruck, Bleisatz, Spezialit?ten
>
> Alemannstr. 21, D-30165 Hannover
> Tel. 0511/3522222, Mobil 0171/2632239
> Fax. 0511/3500439
> hachti at hachti.de
> www.tiegeldruck.de
>
> UStdID DE 202668329
>
>
27 Feb
27 Feb
1:23 a.m.
tis 2013-02-26 klockan 23:47 -0600 skrev Adrian Stoness:
whats vat?
On Tue, Feb 26, 2013 at 5:34 PM, Philipp Hachtmann <hachti at hachti.de> wrote:
>>> and fix a price. It won't be cheap - but very helpful and cool!
Tax and the German vat is compared with the state-ordinated tax in for
example California (what 6 %) rather high. It is a tax on a sellers
markup.
1:42 a.m.
On 2013 Feb 26, at 9:47 PM, Adrian Stoness wrote:
On Tue, Feb 26, 2013 at 5:34 PM, Philipp Hachtmann
<hachti at hachti.de> wrote:
> Am 26.02.2013 19:34, schrieb Adrian Stoness:
>
>> how much?????????
>>
> Depends on interest/lot size. After 3 hours now the price is at
> approx.
> EUR 250/piece without VAT - falling with growing number of boards.
> But it should still become cheaper....
whats vat?
VAT == Value Added Tax. Equivalent to our (Canada's) GST. It's where
our government got the idea for the GST (the European VAT was a few
decades earlier).
2:08 a.m.
do foreners have to pay it?
On Wed, Feb 27, 2013 at 3:42 AM, Brent Hilpert <hilpert at cs.ubc.ca> wrote:
On 2013 Feb 26, at 9:47 PM, Adrian Stoness wrote:
VAT == Value Added Tax. Equivalent to our (Canada's) GST. It's where our
government got the idea for the GST (the European VAT was a few decades
earlier).
On Tue, Feb 26, 2013 at 5:34 PM, Philipp
Hachtmann <hachti at hachti.de wrote:
whats vat?
Am 26.02.2013 19:34, schrieb Adrian Stoness:
how much?????????
Depends on interest/lot size. After 3 hours now the price is at approx.
EUR
250/piece without VAT - falling with growing number of boards.
But it should still become cheaper....
4:18 a.m.
1. In Germany it's currently 19%.
2. I'm quite sure that foreigners don't have to pay it - but they then have to
deal with customs.
When I order something from outside EU, I have to pay the 19% VAT at the customs
office when receiving it.
Kind regards
Philipp
Am 27.02.2013 11:08, schrieb Adrian Stoness:
do foreners have to pay it?
On Wed, Feb 27, 2013 at 3:42 AM, Brent Hilpert<hilpert at cs.ubc.ca> wrote:
> On 2013 Feb 26, at 9:47 PM, Adrian Stoness wrote:
>
>> On Tue, Feb 26, 2013 at 5:34 PM, Philipp Hachtmann<hachti at hachti.de>
>> wrote:
>>
>>> Am 26.02.2013 19:34, schrieb Adrian Stoness:
>>>
>>> how much?????????
>>>>
>>>> Depends on interest/lot size. After 3 hours now the price is at
approx.
>>> EUR 250/piece without VAT - falling with growing number of boards.
>>> But it should still become cheaper....
>>>
>>
> whats vat?
>>
>
> VAT == Value Added Tax. Equivalent to our (Canada's) GST. It's where our
> government got the idea for the GST (the European VAT was a few decades
> earlier).
>
>
--
Dipl.-Inf. (FH) Philipp Hachtmann
Buchdruck, Bleisatz, Spezialit?ten
Alemannstr. 21, D-30165 Hannover
Tel. 0511/3522222, Mobil 0171/2632239
Fax. 0511/3500439
hachti at hachti.de
www.tiegeldruck.de
UStdID DE 202668329
3:39 p.m.
On Wed, Feb 27, 2013 at 01:18:21PM +0100, Philipp Hachtmann wrote:
1. In Germany it's currently 19%.
2. I'm quite sure that foreigners don't have to pay it - but they
then have to deal with customs.
Surprisingly few companies get this right. Amazon handles it correctly
(i.e. buying something at Amazon.de from .ch --> no german VAT charged).
When I order something from outside EU, I have to pay
the 19% VAT at
the customs office when receiving it.
Am 27.02.2013 11:08, schrieb Adrian Stoness:
--
"Opportunity is missed by most people because it is dressed in overalls and
looks like work." -- Thomas A. Edison
do foreners have to pay it?
On Wed, Feb 27, 2013 at 3:42 AM, Brent Hilpert<hilpert at cs.ubc.ca> wrote:
>On 2013 Feb 26, at 9:47 PM, Adrian Stoness wrote:
>
>>On Tue, Feb 26, 2013 at 5:34 PM, Philipp Hachtmann<hachti at hachti.de>
>>wrote:
>>
>>>Am 26.02.2013 19:34, schrieb Adrian Stoness:
>>>
>>> how much?????????
>>>>
>>>> Depends on interest/lot size. After 3 hours now the price is at approx.
>>>EUR 250/piece without VAT - falling with growing number of boards.
>>>But it should still become cheaper....
>>>
>>
> whats vat?
>>
>
>VAT == Value Added Tax. Equivalent to our (Canada's) GST. It's where our
>government got the idea for the GST (the European VAT was a few decades
>earlier).
>
>
--
Dipl.-Inf. (FH) Philipp Hachtmann
Buchdruck, Bleisatz, Spezialit?ten
Alemannstr. 21, D-30165 Hannover
Tel. 0511/3522222, Mobil 0171/2632239
Fax. 0511/3500439
hachti at hachti.de
www.tiegeldruck.de
UStdID DE 202668329 
26 Feb
26 Feb
11:06 a.m.
I should like to buy one or more for my PDP8E.
SPc.
2013/2/26 Philipp Hachtmann <hachti at hachti.de>
Hi folks,
I'd like to introduce my newly designed Omnibus-USB interface.
I designed a quite well working prototype of something that looks like a
KL8E for the PDP8 and like a serial port on the PC - but is none of both :-)
It ist not meant as a console terminal replacement (which it could be used
as) but as an alternative IO device used to dump (archive!) and restore
mass storage media.
To the people who don't know the problems of having MASSES of disks and
tapes to dump: Please don't flame.
Pictures and some more information can be found on my website:
http://pdp8.hachti.de?gallery/**omnibus_usb<http://pdp8.hachti.de?galler…
My intention is to design an improved (probably full height) version and
do a little production run. As I'm currently out of work, selling those
boards could help a bit. I can do it only if I get enough preorders. So I
ask everybody with serious interest to tell me how many boards he wants and
how much he could spend. Based on that feedback I'll decide if I can do it
and fix a price. It won't be cheap - but very helpful and cool!
I'd really like to make some more. It would be great if there's enough
interest to do it.
If you have any suggestions, let me know!
Kind regards,
Philipp :-)
--
Dipl.-Inf. (FH) Philipp Hachtmann
Buchdruck, Bleisatz, Spezialit?ten
Alemannstr. 21, D-30165 Hannover
Tel. 0511/3522222, Mobil 0171/2632239
Fax. 0511/3500439
hachti at hachti.de
www.tiegeldruck.de
UStdID DE 202668329
12:36 p.m.
In article <512CFF9E.3080800 at hachti.de>,
Philipp Hachtmann <hachti at hachti.de> writes:
I'd like to introduce my newly designed
Omnibus-USB interface.
Pictures and some more information can be found on my website:
http://pdp8.hachti.de?gallery/omnibus_usb
I'm guessing that row of DIP chips are line driver/receiver chips for
the bus?
--
"The Direct3D Graphics Pipeline" free book
<http://tinyurl.com/d3d-pipeline>
The Computer Graphics Museum <http://computergraphicsmuseum.org>
The Terminals Wiki <http://terminals.classiccmp.org>
Legalize Adulthood! (my blog) <http://legalizeadulthood.wordpress.com>
6:08 p.m.
On 02/26/2013 01:31 PM, Philipp Hachtmann wrote:
Hi folks,
I'd like to introduce my newly designed Omnibus-USB interface.
I designed a quite well working prototype of something that looks like
a KL8E for the PDP8 and like a serial port on the PC - but is none of
both :-)
No flame intended but...
USB is the least useful interface for PDP-8 as it's all driver dependent
and PDP-8 is slow.
must USB devices do not fit into the 12 bit form well.
One that most users would want is a emulation of some mass storage
device like DECtape or RX02, or
maybe RK05 (or 5F). This is the most often needed item, second only to
memory but that can be
built as semiconductor. The storage is a disk emulation, then can be
USB but IDE is easier to program
on a machine with limited space.
Of the IO for storage SD, and CF are the two best shots as they have the
simplest and lowest protocol needs.
To dump stuff from PDP-8 to PC a serial line is best suited and most
economical to implement even if the host is
crippled and only has USB (use a USB to serial adaptor).
Allison
It ist not meant as a console terminal replacement
(which it could be
used as) but as an alternative IO device used to dump (archive!) and
restore mass storage media.
To the people who don't know the problems of having MASSES of disks
and tapes to dump: Please don't flame.
Pictures and some more information can be found on my website:
http://pdp8.hachti.de?gallery/omnibus_usb
My intention is to design an improved (probably full height) version
and do a little production run. As I'm currently out of work, selling
those boards could help a bit. I can do it only if I get enough
preorders. So I ask everybody with serious interest to tell me how
many boards he wants and how much he could spend. Based on that
feedback I'll decide if I can do it and fix a price. It won't be cheap
- but very helpful and cool!
I'd really like to make some more. It would be great if there's enough
interest to do it.
If you have any suggestions, let me know!
Kind regards,
Philipp :-)
8:37 p.m.
On Tue, Feb 26, 2013 at 09:08:44PM -0500, allison wrote:
One that most users would want is a emulation of some
mass storage
device like DECtape or RX02, or
maybe RK05 (or 5F). This is the most often needed item, [...]
I've been working on that, but it seems silly to finish with all these
other PDP-8 I/O projects popping up and getting Actual Results. Might
still finish it for my own use though (too much $$$ blown not to).
My scheme (largely just on paper but I've done prototype PCBs for
several subassemblies and a whole design for a related PDP-11 project)
is for a posi/negi interface with an XMOS CPU to hack the bus protocol
and handle IOTs, FTDI VNC2 for I/O (to SD cards and/or USB flash
drives), plus a tiny daughterboard for F-RAM to emulate the RS08
(TSS/8!!!).
John Wilson
D Bit
27 Feb
27 Feb
4:13 a.m.
On 02/26/2013 11:37 PM, John Wilson wrote:
On Tue, Feb 26, 2013 at 09:08:44PM -0500, allison
wrote:
I have a proto board I built that uses two port addresses and acts like
a disk
but the parts are static rams (8bit wide 512k x2). One port is read/write,
the other is an address (high 12 bits) and the low 7 bits are just a
counter.
When you set the address it clears the counter and when you read or write a
word the counter advances. the collective result is 19 bits of address
for the ram.
The code has to insure you only read or write 128 words. Extremely
simple. Its
volatile but a small battery solves that. The code has no skip checks
as the
"disk" is far faster than the pdpd-8 and always ready to read or write.
I've been meaning (time as I'm busy) to build a card that take an IDE drive
or CF in 16bit mode and maps the 12 bits into a 16 bit word for data as
a disk.
Storage is a big pdp-8 hardware limitation, memory is often short or
hard to get,
IO like console serial or a simple parallel (PC parallel for printers)
is another.
All of these can be addressed with common modern parts. The caveat is
to keep the
result comparable with standard IO (serial) and disk systems (RS08 or ?)
lacking that
the interface simple as most PDP-8 software only allows a page maybe two
for
a driver (page is 128 words).
I'm afraid that USB driver and protocol is big enough to eat far more
than a
pdp-8 page.
Allison
One that most users would want is a emulation of
some mass storage
device like DECtape or RX02, or
maybe RK05 (or 5F). This is the most often needed item, [...]
I've been
working on that, but it seems silly to finish with all these
other PDP-8 I/O projects popping up and getting Actual Results. Might
still finish it for my own use though (too much $$$ blown not to).
My scheme (largely just on paper but I've done prototype PCBs for
several subassemblies and a whole design for a related PDP-11 project)
is for a posi/negi interface with an XMOS CPU to hack the bus protocol
and handle IOTs, FTDI VNC2 for I/O (to SD cards and/or USB flash
drives), plus a tiny daughterboard for F-RAM to emulate the RS08
(TSS/8!!!).
John Wilson
D Bit
4:38 a.m.
I'm afraid that USB driver and protocol is big
enough to eat far more than a
pdp-8 page.
Read my last post from just a minute ago. There is NO NO NO!!!!!
special
software involved on the PDP8 side. It behaves exactly like a console interface.
With the skip instructions, interrupt flag, interrupt enable flip flop and
everything. Only the behaviour of the teletype transmitter flag is slightly
different. But normal software won't detect that (you cannot set the printer
flag if the FIFO is opened and blocked on PC side. That's all).
Regards
Philipp
--
Dipl.-Inf. (FH) Philipp Hachtmann
Buchdruck, Bleisatz, Spezialit?ten
Alemannstr. 21, D-30165 Hannover
Tel. 0511/3522222, Mobil 0171/2632239
Fax. 0511/3500439
hachti at hachti.de
www.tiegeldruck.de
UStdID DE 202668329
26 Feb
26 Feb
11:15 p.m.
On 2/26/2013 7:08 PM, allison wrote:
On 02/26/2013 01:31 PM, Philipp Hachtmann wrote:
I implemented an RK8E compatible disk controller on my PDP-8 FPGA. The
disk controller simulates 4x RK05s on a single SD Card.
The SD controller is a large state machine.
http://opencores.org/project,pdp8
You would need to 'upgrade' the PLDs with a small FPGA - but I would
think that it would be very easy to re-target this to a real Omnibus
implementation. The hard part is done.
Rob.
Hi folks,
One that most users would want is a emulation of some mass storage
device like DECtape or RX02, or maybe RK05 (or 5F). This is the
most often needed item, second only to memory but that can be built
as semiconductor. The storage is a disk emulation, then can be
USB but IDE is easier to program on a machine with limited space.
Of the IO for storage SD, and CF are the two best shots as they have
the simplest and lowest protocol needs.
27 Feb
27 Feb
4:33 a.m.
Hi Allison,
No flame intended but...
But?
USB is the least useful interface for PDP-8 as
it's all driver dependent and
PDP-8 is slow.
I think its a wonderful interface the way I currently use it. The
FTDI chip is
recognized as an USB serial converter. In Windows you need FTDI's standard
driver, Linux supports the chip via it's mainline ftdio_sio driver. Plug it in
and it works.
My current interface is designed to do direct transfers between the PC and the
PDP8 without too much software issues. And that's exactly what my solution
provides. There's no more simpler interface than the console TTY interface on
the PDP8 which is implemented on that side of the wire.
must USB devices do not fit into the 12 bit form well.
Console TTY is 8 bit only as well.
One that most users would want is a emulation of some
mass storage device like
DECtape or RX02, or
maybe RK05 (or 5F). This is the most often needed item,
Yes? The board is NOT (!!)
intended to replace any (probably missing) vintage
hardware. If you need an RK05 on your pdp8: Use an RK05! It is for those who
have RK05, DECtape etc. in quantities and want to be able to make quick backups
and restores to that *real* media.
Emulating a RK05 can be fun. But it's quite another approach. For making
frequent backups and restores, an SD card solution is considered quite
unpracticable - at least by me.
second only to memory
but that can be
built as semiconductor.
As above: I'm currently not talking about building
replacements for real big
iron. If you need core: Simply throw in some core memory.
To dump stuff from PDP-8 to PC a serial line is best
suited and most economical
to implement even if the host is
crippled and only has USB (use a USB to serial adaptor).
Oh, you seem to have
missed the central point.
Yes, a serial line is ideal. But slow! The board I designed is a plug-in
replacement for the PDP8's serial interface. It is software compatible and can
be plugged in without any changes in software. Most of the software (except
stuff like dumprest that makes assumptions on the expected data rate) runs with
it without *ANY* programming involved.
And on the PC side it presents itself as exactly one of those USB to serial
converters.
The only difference is that it's lightning fast and does not loose data when the
receiver stops fetching data.
Kind regards
Philipp
Allison
> It ist not meant as a console terminal replacement (which it could be used as)
> but as an alternative IO device used to dump (archive!) and restore mass
> storage media.
> To the people who don't know the problems of having MASSES of disks and tapes
> to dump: Please don't flame.
>
> Pictures and some more information can be found on my website:
> http://pdp8.hachti.de?gallery/omnibus_usb
>
> My intention is to design an improved (probably full height) version and do a
> little production run. As I'm currently out of work, selling those boards
> could help a bit. I can do it only if I get enough preorders. So I ask
> everybody with serious interest to tell me how many boards he wants and how
> much he could spend. Based on that feedback I'll decide if I can do it and fix
> a price. It won't be cheap - but very helpful and cool!
>
> I'd really like to make some more. It would be great if there's enough
> interest to do it.
>
> If you have any suggestions, let me know!
>
>
> Kind regards,
>
> Philipp :-)
>
--
Dipl.-Inf. (FH) Philipp Hachtmann
Buchdruck, Bleisatz, Spezialit?ten
Alemannstr. 21, D-30165 Hannover
Tel. 0511/3522222, Mobil 0171/2632239
Fax. 0511/3500439
hachti at hachti.de
www.tiegeldruck.de
UStdID DE 202668329
10 a.m.
Philipp Hachtmann <hachti at hachti.de> writes:
I'd like to introduce my newly designed
Omnibus-USB interface.
That's awesome. :) Very nice work.
I've been thinking for a few weeks about building a fast data-dumping
device for rescuing data (e.g. large disk images) from classic machines
that just looks like a printer. It looks like the FT240X would make that
really easy...
--
Adam Sampson <ats at offog.org> <http://offog.org/>
4098
days inactive
4100
days old
35 comments
17 participants
participants (17)
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