18 Jul
2016
18 Jul
'16
9:25 p.m.
Probably a question for Tony's encyclopedic knowledge. I just scored two HP 9825, one
a later "T" option and one "B" version with all the fixings (i.e ROM
packs). They both seem to work save the usual tape drive which I have not gotten to yet.
Both have the flexible disc ROM. What kind of discs can I hook up? I think the HP 9895
8" floppy would work. What about the HP 82901 5.25" floppy drive? How do I
read/write program files from the disc interface?
Marc
Sent from my iPad
18 Jul
18 Jul
10:06 p.m.
Probably a question for Tony's encyclopedic
knowledge. I just
scored two HP 9825, one a later "T" option and one "B" version
with all the fixings (i.e ROM packs). They both seem to work
save the usual tape drive which I have not gotten to yet. Both
have the flexible disc ROM. What kind of discs can I hook up?
Which flexible disk ROM? There are 2. The older one, AFAIK
supports the HP9885 8" drive which has a 16 bit parallel interface
and needs the right version of the 98032 to hook it up. The later
disk ROM supports the HP9895 on HPIB.
The older ROM needs a disk with various programs on it to
work, it is essentially just a bootstrap. Have any such disks
survived?
-tony
10:29 p.m.
On Jul 18, 2016, at 10:06 PM, tony duell <ard at p850ug1.demon.co.uk> wrote:
I didn't look at the back to see what interface it has, but there was an HP 9885M that
looked pretty decent at Weird Stuff on Sunday ($75).
It was atop an HP 9000/236 ($150).
There were a couple other HP PA-RISC systems there, as well as a couple IBM RS/6000
desktops and what looked like a PS/2 Model 80, an Epson of some sort, and a Panasonic Sr.
Partner.
And a nice looking Macintosh LC III for which they were asking too much, though I still
considered it seriously since it was an LC III with an included 10Base-T card?
-- Chris
Probably a question for Tony's encyclopedic
knowledge. I just
scored two HP 9825, one a later "T" option and one "B" version
with all the fixings (i.e ROM packs). They both seem to work
save the usual tape drive which I have not gotten to yet. Both
have the flexible disc ROM. What kind of discs can I hook up?
Which flexible disk ROM? There are 2. The older one, AFAIK
supports the HP9885 8" drive which has a 16 bit parallel interface
and needs the right version of the 98032 to hook it up. The later
disk ROM supports the HP9895 on HPIB. 
19 Jul
19 Jul
5:54 a.m.
On 2016-07-19 2:06 AM, tony duell wrote:
The only difference between the different
versions of 98032A is the
cable and some jumpers inside but it appears to all be documented so
even if you don't have the option 085 98032A, the 50 pin D shell
connector used on the 9885 is pretty common.
Probably a question for Tony's encyclopedic
knowledge. I just
scored two HP 9825, one a later "T" option and one "B" version
with all the fixings (i.e ROM packs). They both seem to work
save the usual tape drive which I have not gotten to yet. Both
have the flexible disc ROM. What kind of discs can I hook up?
Which flexible disk
ROM? There are 2. The older one, AFAIK
supports the HP9885 8" drive which has a 16 bit parallel interface
and needs the right version of the 98032 to hook it up. The later
disk ROM supports the HP9895 on HPIB.
The older ROM needs a disk with various programs on it to
work, it is essentially just a bootstrap. Have any such disks
survived?
There is an image of one on the hpmuseum.net site.
-tony
Paul.
7:03 p.m.
Great info. I'm on travel but I will check which ROMs I have when I come back on
Friday.
Marc
On Jul 19, 2016, at 2:06 PM, tony duell <ard at
p850ug1.demon.co.uk> wrote:
Probably a question for Tony's encyclopedic
knowledge. I just
scored two HP 9825, one a later "T" option and one "B" version
with all the fixings (i.e ROM packs). They both seem to work
save the usual tape drive which I have not gotten to yet. Both
have the flexible disc ROM. What kind of discs can I hook up?
Which flexible disk ROM? There are 2. The older one, AFAIK
supports the HP9885 8" drive which has a 16 bit parallel interface
and needs the right version of the 98032 to hook it up. The later
disk ROM supports the HP9895 on HPIB.
The older ROM needs a disk with various programs on it to
work, it is essentially just a bootstrap. Have any such disks
survived?
-tony
22 Jul
22 Jul
5:17 p.m.
Unfortunately, I have the older ROM, the HP 98217A. Says 9885 Flexible Disk
Drive on it (duh). Only this 9885, single side low density 8" drive,
connected with the parallel interface and a special cable is supported. And
indeed as Tony says, to start from a blank disk, you need a tape cartridge
that has the "disc system" on it and run an initialize program to copy files
on the first disc sectors. If you don't have a copy of that cartridge then
you are hosed even with that ROM. So I am hosed twice: I don't have a 9885
drive and I don't have the cartridge. And I suspect a cartridge that's
readable doesn't exist anymore.
The newer ROM is the HP 98228. Which can ONLY work in a later HP 9825T (not
the A nor the B), and can drive the aforementioned 8" 9885 with the parallel
interface, and also the 9895 double sided double density double drive via
the HP-IB interface. But only with the "revised" HP-IB interface, not the
original interface. Very picky that ROM. Bu for the 9885 disc, it does not
have the cartridge requirement (yeah!). I have the 9825T, the 9895 drive,
the revised interface, but not the right ROM. Hosed again.
The details are in the 9825 Disc ROM Manual:
http://www.hpmuseum.net/document.php?hwfile=1864
Marc
Probably a
question for Tony's encyclopedic knowledge. I just scored
two HP 9825, one a later "T" option and one "B" version with all the
fixings (i.e ROM packs). They both seem to work save the usual tape
drive which I have not gotten to yet. Both have the flexible disc ROM.
What kind of discs can I hook up?
Which flexible disk ROM? There are 2. The older one, AFAIK supports the
HP9885 8" drive which has a 16 bit parallel interface and needs the right
version of the 98032 to hook it up. The later disk ROM supports the HP9895
on HPIB.
The older ROM needs a disk with various programs on it to work, it is
essentially just a bootstrap. Have any such disks survived?
-tony
6:58 p.m.
On 2016-07-22 9:17 PM, CuriousMarc wrote:
Unfortunately, I have the older ROM, the HP 98217A.
Says 9885 Flexible Disk
Drive on it (duh). Only this 9885, single side low density 8" drive,
connected with the parallel interface and a special cable is supported. And
indeed as Tony says, to start from a blank disk, you need a tape cartridge
that has the "disc system" on it and run an initialize program to copy files
on the first disc sectors. If you don't have a copy of that cartridge then
you are hosed even with that ROM. So I am hosed twice: I don't have a 9885
drive and I don't have the cartridge. And I suspect a cartridge that's
readable doesn't exist anymore.
The newer ROM is the HP 98228. Which can ONLY work in a later HP 9825T (not
the A nor the B), and can drive the aforementioned 8" 9885 with the parallel
interface, and also the 9895 double sided double density double drive via
the HP-IB interface. But only with the "revised" HP-IB interface, not the
original interface. Very picky that ROM. Bu for the 9885 disc, it does not
have the cartridge requirement (yeah!). I have the 9825T, the 9895 drive,
the revised interface, but not the right ROM. Hosed again.
The details are in the 9825 Disc ROM Manual:
http://www.hpmuseum.net/document.php?hwfile=1864
Marc
On the hpmuseum.net page for the 98217A ROM here is an image of what is
reputed to be an initialized diskette for use with 9825 and 98217A
http://www.hpmuseum.net/display_item.php?hw=166. When I get my 9825T I
will look into 9885 emulation, I don't think it will be too difficult
but you may still need a GPIO unless I build the whole thing onto a
plug-in card I don't think the GPIO would be too difficult to clone.
But ideally I would still like to get access to a 98228A ROM to dump and
clone it, even though it is bank switched it should still be possible.
Paul.
23 Jul
23 Jul
12:40 a.m.
Thanks, I didn't know, I grabbed the image. That offers a path if I can ever
get an 9885 and single sides 8" discs...
Marc
-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Paul
Berger
On the hpmuseum.net page for the 98217A ROM here is an image of what is
reputed to be an initialized diskette for use with 9825 and 98217A
http://www.hpmuseum.net/display_item.php?hw=166. When I get my
9825T I will look into 9885 emulation, I don't think it will be too
difficult
but
you may still need a GPIO unless I build the whole
thing onto a
plug-in card I don't think the GPIO would be too difficult to clone.
But ideally I would still like to get access to a 98228A ROM to dump and
clone
it, even though it is bank switched it should still be
possible.
Paul.
24 Jul
24 Jul
3:30 a.m.
Guys, I've looked for a 98228A ROM in the HP Computer Museum but haven't
been able to find one - but it looks like we've had one at some stage
judging by the photo.
If I come across it I'll come back to you.
David Collins
Curator
-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of CuriousMarc
Sent: Saturday, 23 July 2016 5:40 PM
To: 'General Discussion: On-Topic and Off-Topic Posts'
<cctalk at classiccmp.org>
Subject: RE: Flex Disc options for the HP 9825
Thanks, I didn't know, I grabbed the image. That offers a path if I can ever
get an 9885 and single sides 8" discs...
Marc
-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Paul
Berger On the hpmuseum.net page for the 98217A ROM here is an image of
what is reputed to be an initialized diskette for use with 9825 and
98217A http://www.hpmuseum.net/display_item.php?hw=166. When I get my
9825T I will look into 9885 emulation, I don't think it will be too
difficult
but
you may still need a GPIO unless I build the whole
thing onto a
plug-in card I don't think the GPIO would be too difficult to clone.
But ideally I would still like to get access to a 98228A ROM to dump
and
clone
it, even though it is bank switched it should still be
possible.
Paul.
4:31 a.m.
Thanks for looking!
Marc
On Jul 24, 2016, at 3:30 AM, David Collins
<davidk.collins at bigpond.com> wrote:
Guys, I've looked for a 98228A ROM in the HP Computer Museum but haven't
been able to find one - but it looks like we've had one at some stage
judging by the photo.
If I come across it I'll come back to you.
David Collins
Curator
-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of CuriousMarc
Sent: Saturday, 23 July 2016 5:40 PM
To: 'General Discussion: On-Topic and Off-Topic Posts'
<cctalk at classiccmp.org>
Subject: RE: Flex Disc options for the HP 9825
Thanks, I didn't know, I grabbed the image. That offers a path if I can ever
get an 9885 and single sides 8" discs...
Marc
-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Paul
Berger On the hpmuseum.net page for the 98217A ROM here is an image of
what is reputed to be an initialized diskette for use with 9825 and
98217A http://www.hpmuseum.net/display_item.php?hw=166. When I get my
9825T I will look into 9885 emulation, I don't think it will be too
difficult
but
you may still need a GPIO unless I build the
whole thing onto a
plug-in card I don't think the GPIO would be too difficult to clone.
But ideally I would still like to get access to a 98228A ROM to dump
and
clone
it, even though it is bank switched it should
still be possible.
Paul.
9 Dec
9 Dec
4:36 p.m.
Some time ago there was a discussion about the elusive 98228A ROM that
supports both the 9885 and 9895 diskette drive units on a 9825T, well
good news! A fellow MoHPC member David Ramsey very kindly loaned me
his, and with a little careful reading of the service manual along with
studying Tony Duell's schematic I got a good idea of how it work, and
observing the memory bus using a logic analyzer confirmed how it
worked. I was able to dump the ROM using GPIO cards in a 9920 to
simulate the memory bus, I actually went on and dumped all the ROMs in
the 9825T as well as a couple other I had. I have successfully created
a clone of the ROM and have even fit it into a a ROM shell. I am going
to try creating a PCB for it too, what I have now is just hand wired,
but it works. In the end the ROM module did not turn out to be very
complicated. I am just in the process of documenting my project and
will release a package soon with full documentation and most importantly
the ROM image. I plan to donate my package along with all of my ROM
images to hpmuseum.net.
Paul.
10 Dec
10 Dec
9:27 a.m.
Fantastic! Can't wait for the info.
Marc
On Dec 9, 2016, at 4:36 PM, Paul Berger <phb.hfx at
gmail.com> wrote:
Some time ago there was a discussion about the elusive 98228A ROM that supports both the
9885 and 9895 diskette drive units on a 9825T, well good news! A fellow MoHPC member
David Ramsey very kindly loaned me his, and with a little careful reading of the service
manual along with studying Tony Duell's schematic I got a good idea of how it work,
and observing the memory bus using a logic analyzer confirmed how it worked. I was able
to dump the ROM using GPIO cards in a 9920 to simulate the memory bus, I actually went on
and dumped all the ROMs in the 9825T as well as a couple other I had. I have successfully
created a clone of the ROM and have even fit it into a a ROM shell. I am going to try
creating a PCB for it too, what I have now is just hand wired, but it works. In the end
the ROM module did not turn out to be very complicated. I am just in the process of
documenting my project and will release a package soon with full documentation and most
importantly the ROM image. I plan to donate my package along with all of my ROM images to
hpmuseum.net.
Paul.
11:49 a.m.
-----Oorspronkelijk bericht-----
Van: cctech [mailto:cctech-bounces at classiccmp.org] Namens Paul Berger
Verzonden: zaterdag 10 december 2016 1:37
Aan: General Discussion: On-Topic and Off-Topic Posts
Onderwerp: Re: Flex Disc options for the HP 9825
Some time ago there was a discussion about the elusive 98228A ROM that
supports both the 9885 and 9895 diskette drive units on a 9825T, well good
news! A fellow MoHPC member David Ramsey very kindly loaned me his, and
with a little careful reading of the service manual along with studying
Tony
Duell's schematic I got a good idea of how it
work, and observing the
memory
bus using a logic analyzer confirmed how it worked. I
was able to dump
the
ROM using GPIO cards in a 9920 to simulate the memory
bus, I actually went
on
and dumped all the ROMs in the 9825T as well as a
couple other I had. I
have
successfully created a clone of the ROM and have even
fit it into a a ROM
shell.
I am going to try creating a PCB for it too, what I
have now is just hand
wired,
but it works. In the end the ROM module did not turn
out to be very
complicated. I am just in the process of documenting my project and will
release a package soon with full documentation and most importantly the
ROM
image. I plan to donate my package along with all of
my ROM images to
hpmuseum.net.
Paul.
Great work Paul.
-Rik
12 Aug
12 Aug
1:30 a.m.
I got the HP 9885 single sided disk unit that was at Weird Stuff, thanks for the heads up!
Now I just need a parallel interface for the 9825, a cable, the right 8" diskettes,
and get my HP-IB 9895 to work... That's a lot of stars to align but that should be fun
to try.
Marc
On Jul 24, 2016, at 3:30 AM, David Collins
<davidk.collins at bigpond.com> wrote:
Guys, I've looked for a 98228A ROM in the HP Computer Museum but haven't
been able to find one - but it looks like we've had one at some stage
judging by the photo.
If I come across it I'll come back to you.
David Collins
Curator
-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of CuriousMarc
Sent: Saturday, 23 July 2016 5:40 PM
To: 'General Discussion: On-Topic and Off-Topic Posts'
<cctalk at classiccmp.org>
Subject: RE: Flex Disc options for the HP 9825
Thanks, I didn't know, I grabbed the image. That offers a path if I can ever
get an 9885 and single sides 8" discs...
Marc
-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Paul
Berger On the hpmuseum.net page for the 98217A ROM here is an image of
what is reputed to be an initialized diskette for use with 9825 and
98217A http://www.hpmuseum.net/display_item.php?hw=166. When I get my
9825T I will look into 9885 emulation, I don't think it will be too
difficult
but
you may still need a GPIO unless I build the
whole thing onto a
plug-in card I don't think the GPIO would be too difficult to clone.
But ideally I would still like to get access to a 98228A ROM to dump
and
clone
it, even though it is bank switched it should
still be possible.
Paul.
8:15 a.m.
The cable will come with the GPIO, the one you want is the 98032A option
085, but if you cannot find one of them any 98032A could be reconfigured
to support a 9885. Diskettes are going to be a bigger issue, as per
hpmuseum.net you will need a 9895 to be able to transfer their image to
a physical diskette.
Paul.
On 2016-08-12 5:30 AM, curiousmarc3 at gmail.com wrote:
I got the HP 9885 single sided disk unit that was at
Weird Stuff, thanks for the heads up! Now I just need a parallel interface for the 9825, a
cable, the right 8" diskettes, and get my HP-IB 9895 to work... That's a lot of
stars to align but that should be fun to try.
Marc
> On Jul 24, 2016, at 3:30 AM, David Collins <davidk.collins at bigpond.com>
wrote:
>
> Guys, I've looked for a 98228A ROM in the HP Computer Museum but haven't
> been able to find one - but it looks like we've had one at some stage
> judging by the photo.
>
> If I come across it I'll come back to you.
>
> David Collins
> Curator
>
>
> -----Original Message-----
> From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of CuriousMarc
> Sent: Saturday, 23 July 2016 5:40 PM
> To: 'General Discussion: On-Topic and Off-Topic Posts'
> <cctalk at classiccmp.org>
> Subject: RE: Flex Disc options for the HP 9825
>
> Thanks, I didn't know, I grabbed the image. That offers a path if I can ever
> get an 9885 and single sides 8" discs...
> Marc
>
>> -----Original Message-----
>> From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Paul
>> Berger On the hpmuseum.net page for the 98217A ROM here is an image of
>> what is reputed to be an initialized diskette for use with 9825 and
>> 98217A http://www.hpmuseum.net/display_item.php?hw=166. When I get my
>> 9825T I will look into 9885 emulation, I don't think it will be too
> difficult but
>> you may still need a GPIO unless I build the whole thing onto a
>> plug-in card I don't think the GPIO would be too difficult to clone.
>> But ideally I would still like to get access to a 98228A ROM to dump
>> and
> clone
>> it, even though it is bank switched it should still be possible.
>>
>> Paul.
>
13 Aug
13 Aug
2:37 a.m.
For what it's worth a small warning about the HP 9825 series computers.
The power supply doesn't have a crowbar(over voltage protection), so a
transistor failure in the Psu can be catastrophic.
On the other hand the two 9835's I have, which uses the same form factor and
almost the same power supply layout are HP modified with crowbars added.
It seems to be good practice to add some ov-protection to the HP 9825 supply
because the switching transistor and 723 voltage regulators don't have the
eternal life.
And there no certain prediction in how they fail, short or open circuit, I
found out the hard way several years ago.
-Rik
3:15 a.m.
Thanks for the info. Any schematics of the modification?
Marc
On Aug 13, 2016, at 2:37 AM, Rik Bos <hp-fix at
xs4all.nl> wrote:
For what it's worth a small warning about the HP 9825 series computers.
The power supply doesn't have a crowbar(over voltage protection), so a
transistor failure in the Psu can be catastrophic.
On the other hand the two 9835's I have, which uses the same form factor and
almost the same power supply layout are HP modified with crowbars added.
It seems to be good practice to add some ov-protection to the HP 9825 supply
because the switching transistor and 723 voltage regulators don't have the
eternal life.
And there no certain prediction in how they fail, short or open circuit, I
found out the hard way several years ago.
-Rik
1:19 p.m.
Marc,
Building a crowbar is easy, just take a Zener a little higher than the psu
voltage eg 5.2V for 5V rail put a resistor of 1k in series take a Thyristor
big enough to take about 150% of the schort current and connect it to the
zener through a small resistor. I suppose you can do the math ;)
Be sure to put a crowbar on both the +12V and +5V and you could consider one
on the -12V rail but that voltage doesn't have a pass transistor but a 320K
voltage regulator which has a reasonable protection for over voltage.
The -5V is connected to the -12V through a zener.
Tony reverse engineered the schematics, you can download them a the HP
Museum website or become a member of the HPCC and order the CD with all
Tony's diagrams (a lot of eexcellent work).
-Rik
-----Oorspronkelijk bericht-----
Van: cctech [mailto:cctech-bounces at classiccmp.org] Namens
curiousmarc3 at gmail.com
Verzonden: zaterdag 13 augustus 2016 12:15
Aan: General Discussion: On-Topic Posts
Onderwerp: Re: Flex Disc options for the HP 9825
Thanks for the info. Any schematics of the modification?
Marc
On Aug 13, 2016, at 2:37 AM, Rik Bos <hp-fix
at xs4all.nl> wrote:
For what it's worth a small warning about the HP 9825 series computers.
The power supply doesn't have a crowbar(over voltage protection), so a
transistor failure in the Psu can be catastrophic.
On the other hand the two 9835's I have, which uses the same form
factor and almost the same power supply layout are HP modified with
crowbars
added.
> It seems to be good practice to add some ov-protection to the HP 9825
> supply because the switching transistor and 723 voltage regulators
> don't have the eternal life.
> And there no certain prediction in how they fail, short or open
> circuit, I found out the hard way several years ago.
>
> -Rik
>
14 Aug
14 Aug
12:27 a.m.
Thanks!
Marc
On Aug 13, 2016, at 1:19 PM, Rik Bos <hp-fix at
xs4all.nl> wrote:
Marc,
Building a crowbar is easy, just take a Zener a little higher than the psu
voltage eg 5.2V for 5V rail put a resistor of 1k in series take a Thyristor
big enough to take about 150% of the schort current and connect it to the
zener through a small resistor. I suppose you can do the math ;)
Be sure to put a crowbar on both the +12V and +5V and you could consider one
on the -12V rail but that voltage doesn't have a pass transistor but a 320K
voltage regulator which has a reasonable protection for over voltage.
The -5V is connected to the -12V through a zener.
Tony reverse engineered the schematics, you can download them a the HP
Museum website or become a member of the HPCC and order the CD with all
Tony's diagrams (a lot of eexcellent work).
-Rik
-----Oorspronkelijk bericht-----
Van: cctech [mailto:cctech-bounces at classiccmp.org] Namens
curiousmarc3 at gmail.com
Verzonden: zaterdag 13 augustus 2016 12:15
Aan: General Discussion: On-Topic Posts
Onderwerp: Re: Flex Disc options for the HP 9825
Thanks for the info. Any schematics of the modification?
Marc
On Aug 13, 2016, at 2:37 AM, Rik Bos <hp-fix
at xs4all.nl> wrote:
For what it's worth a small warning about the HP 9825 series computers.
The power supply doesn't have a crowbar(over voltage protection), so a
transistor failure in the Psu can be catastrophic.
On the other hand the two 9835's I have, which uses the same form
factor and almost the same power supply layout are HP modified with
crowbars
added.
> It seems to be good practice to add some ov-protection to the HP 9825
> supply because the switching transistor and 723 voltage regulators
> don't have the eternal life.
> And there no certain prediction in how they fail, short or open
> circuit, I found out the hard way several years ago.
>
> -Rik 
13 Aug
13 Aug
9:51 a.m.
On 13.08.2016 11:37, Rik Bos wrote:
For what it's worth a small warning about the HP 9825 series computers.
The power supply doesn't have a crowbar(over voltage protection), so a
transistor failure in the Psu can be catastrophic.
On the other hand the two 9835's I have, which uses the same form factor and
almost the same power supply layout are HP modified with crowbars added.
It seems to be good practice to add some ov-protection to the HP 9825 supply
because the switching transistor and 723 voltage regulators don't have the
eternal life.
And there no certain prediction in how they fail, short or open circuit, I
found out the hard way several years ago.
-Rik
The same is true of the PDP8/L. I also found out the hard way....
That L is still not running, but the PS now has a crowbar !
Jos
3:19 p.m.
I wonder if the crowbars might have been a later revision of of the
power supply. After the accident with my 9835A I had to completely
rebuild the +12V regulator both the 723 and the pass transistor as well
as a few passive components. I did not see any evidence of crowbars,
and the power supply in my 9835A seems to match the diagram in the 9835
service guide. If I was to add crowbars to this power supply I would be
temped to monitor the voltages and crowbar the raw DC when an
overvoltage is detected, in my case it was the -20V raw that did all of
the damage.
Paul.
On 2016-08-13 6:37 AM, Rik Bos wrote:
For what it's worth a small warning about the HP
9825 series computers.
The power supply doesn't have a crowbar(over voltage protection), so a
transistor failure in the Psu can be catastrophic.
On the other hand the two 9835's I have, which uses the same form factor and
almost the same power supply layout are HP modified with crowbars added.
It seems to be good practice to add some ov-protection to the HP 9825 supply
because the switching transistor and 723 voltage regulators don't have the
eternal life.
And there no certain prediction in how they fail, short or open circuit, I
found out the hard way several years ago.
-Rik
14 Aug
14 Aug
10:22 a.m.
Paul,
It is a small extra pcb( with hp logo). Both my machines are build in Germany, which is
logic because I?m living in the Netherlands and aquired both in Europe.
So it could be a local modification made by the Boeblingen factory or even HP
Netherlands.
I?m happy with it?
-Rik
Van: Paul Berger
12:07 p.m.
Would you pictures of it and where it sits in the machine by any chance?
Marc
Sent from my iPad
On Aug 14, 2016, at 10:22 AM, Rik Bos <hp-fix at
xs4all.nl> wrote:
Paul,
It is a small extra pcb( with hp logo). Both my machines are build in Germany, which is
logic because I?m living in the Netherlands and aquired both in Europe.
So it could be a local modification made by the Boeblingen factory or even HP
Netherlands.
I?m happy with it?
-Rik
Van: Paul Berger
15 Aug
15 Aug
7:35 a.m.
https://flic.kr/p/L8SNPJ
Done.
-Rik
-----Oorspronkelijk bericht-----
Van: cctech [mailto:cctech-bounces at classiccmp.org] Namens Curious Marc
Verzonden: zondag 14 augustus 2016 21:08
Aan: General Discussion: On-Topic Posts
Onderwerp: Re: Flex Disc options for the HP 9825
Would you pictures of it and where it sits in the machine by any chance?
Marc
Sent from my iPad
On Aug 14, 2016, at 10:22 AM, Rik Bos <hp-fix
at xs4all.nl> wrote:
Paul,
It is a small extra pcb( with hp logo). Both my machines are build in Germany,
which is logic because I?m living in the Netherlands and aquired both in Europe.
So it could be a local modification made by the
Boeblingen factory or even HP
Netherlands.
> I?m happy with it?
>
> -Rik
>
> Van: Paul Berger
8:01 a.m.
Wow that is a nicely done add-on, It looks like it monitors +5 and +12
and crowbars the RAW +20. Did they insert any fuses? or do they rely
on that blowing the main fuse? That should be easy to duplicate even on
a breadboard....
Paul
On 2016-08-15 11:35 AM, Rik Bos wrote:
https://flic.kr/p/L8SNPJ
Done.
-Rik
> -----Oorspronkelijk bericht-----
> Van: cctech [mailto:cctech-bounces at classiccmp.org] Namens Curious Marc
> Verzonden: zondag 14 augustus 2016 21:08
> Aan: General Discussion: On-Topic Posts
> Onderwerp: Re: Flex Disc options for the HP 9825
>
> Would you pictures of it and where it sits in the machine by any chance?
> Marc
>
> Sent from my iPad
>
>> On Aug 14, 2016, at 10:22 AM, Rik Bos <hp-fix at xs4all.nl> wrote:
>>
>> Paul,
>>
>> It is a small extra pcb( with hp logo). Both my machines are build in Germany,
> which is logic because I?m living in the Netherlands and aquired both in Europe.
>> So it could be a local modification made by the Boeblingen factory or even HP
> Netherlands.
>> I?m happy with it?
>>
>> -Rik
>>
>> Van: Paul Berger
1:58 p.m.
On Mon, Aug 15, 2016 at 9:25 AM, Rik Bos <hp-fix at xs4all.nl> wrote:
No, they just blow the main fuse.
The thyristor is a 2N4441.
-Rik
Van: Paul Berger
In my experience, 'blow the main fuse' is the usual approach with a crowbar
- in other words, trigger the protection device that already exists.
--
Ian S. King, MSIS, MSCS, Ph.D. Candidate
The Information School <http://ischool.uw.edu>
Dissertation: "Why the Conversation Mattered: Constructing a Sociotechnical
Narrative Through a Design Lens
Archivist, Voices From the Rwanda Tribunal <http://tribunalvoices.org>
Value Sensitive Design Research Lab <http://vsdesign.org>
University of Washington
There is an old Vulcan saying: "Only Nixon could go to China."
16 Aug
16 Aug
1:11 a.m.
Thanks. That's a very clean mod!
Marc
On Aug 15, 2016, at 7:35 AM, Rik Bos <hp-fix at
xs4all.nl> wrote:
https://flic.kr/p/L8SNPJ
Done.
-Rik
-----Oorspronkelijk bericht-----
Van: cctech [mailto:cctech-bounces at classiccmp.org] Namens Curious Marc
Verzonden: zondag 14 augustus 2016 21:08
Aan: General Discussion: On-Topic Posts
Onderwerp: Re: Flex Disc options for the HP 9825
Would you pictures of it and where it sits in the machine by any chance?
Marc
Sent from my iPad
On Aug 14, 2016, at 10:22 AM, Rik Bos <hp-fix
at xs4all.nl> wrote:
Paul,
It is a small extra pcb( with hp logo). Both my machines are build in Germany,
which is logic because I?m living in the Netherlands and aquired both in Europe.
So it could be a local modification made by the
Boeblingen factory or even HP
Netherlands.
> I?m happy with it?
>
> -Rik
>
> Van: Paul Berger
19 Jul
19 Jul
6 a.m.
On 2016-07-19 1:25 AM, Curious Marc wrote:
Probably a question for Tony's encyclopedic
knowledge. I just scored two HP 9825, one a later "T" option and one
"B" version with all the fixings (i.e ROM packs). They both seem to work save
the usual tape drive which I have not gotten to yet. Both have the flexible disc ROM. What
kind of discs can I hook up? I think the HP 9895 8" floppy would work. What about the
HP 82901 5.25" floppy drive? How do I read/write program files from the disc
interface?
Marc
Sent from my iPad
There was only ever support for 8" diskette drives, and to
support 9895
you need the second version of the Diskette ROM which appears to be very
rare. I t sure would be nice if someone who has one of these ROMs would
dump the contents or loan it to someone who could dump it, so that we
might be able to clone the ROM module.
Paul.
10:25 a.m.
There was only ever support for 8" diskette
drives, and to support 9895
you need the second version of the Diskette ROM which appears to be very
rare. I t sure would be nice if someone who has one of these ROMs would
dump the contents or loan it to someone who could dump it, so that we
might be able to clone the ROM module.
It's not totally trivial. The later version module is so large that part of the
ROM is bank-switched. So you would have to make sure you copied the
entire ROM and the copied the bank-switching circuitry in the cloned
module.
-tony
11:22 a.m.
On 2016-07-19 2:25 PM, tony duell wrote:
Yes I saw your schematic, it does not seem too big of a challenge, but
on the other hand it may be bank switched just because it supports both
diskette drives and both halve may not be required to support only 9895,
but without a dump that is only speculation.
Paul.
There was only
ever support for 8" diskette drives, and to support 9895
you need the second version of the Diskette ROM which appears to be very
rare. I t sure would be nice if someone who has one of these ROMs would
dump the contents or loan it to someone who could dump it, so that we
might be able to clone the ROM module.
It's not totally trivial. The later
version module is so large that part of the
ROM is bank-switched. So you would have to make sure you copied the
entire ROM and the copied the bank-switching circuitry in the cloned
module.
-tony
2933
days inactive
3077
days old
30 comments
8 participants
participants (8)
-
ard＠p850ug1.demon.co.uk -
cmhanson＠eschatologist.net -
curiousmarc3＠gmail.com -
davidk.collins＠bigpond.com -
hp-fix＠xs4all.nl -
isking＠uw.edu -
jos.dreesen＠bluewin.ch -
phb.hfx＠gmail.com