Re: SGI Indigo, WTB Power supply? Burning smell?

[ethan]

I started up my indigo today, it has the same time of day error. The chime 
does play before the message is displayed.

--Devin


Thanks for the info! So good chance the capacitor that is fried in mine 
might be related to the audio section. Going to pick up a caliper so I can 
measure the physical size of the SMD caps and start making a list to 
replace.


- Ethan


--
Ethan O'Toole

Re: SGI Indigo, WTB Power supply? Burning smell?

[Devin]

I started up my indigo today, it has the same time of day error. The 
chime does play before the message is displayed.



--Devin


On 12/10/2016 11:55 AM, et...@757.org wrote:
After sniffing the PCBs for a minute or so like bomb dog looking for 
a burned resistor or cap I got to thinking that the PCBs are 
bigger than I remembered. Better than I remembered.


Found the fried component! A surface mount yellow rectangular 
capacitor mounted on the bottom of the CPU board, somewhat near the 
audio DAC section. I wonder if all the similar caps that are on the 
bottom should be replaced. Maybe one went bad, but if one went then 
the others might be at risk as well.


After removing the PSU to open it up, I found that it's the R4K model 
power supply (Yay!) and there doesn't seem to be anything fried in it.


One odd thing, and I can't remember my SGI enough. I get the TOD clock 
error on the Indigo, and I get no startup chime tune sound. It had 
kind of a sputtering tick from the speaker (perhaps the fried cap is 
in the audio section.) Anyone know if the chime should play before the 
time of day clock error?



--
Ethan O'Toole

Re: Odd "endianness" [was Re: RE: Base 64 posts to the list]

[Eric Smith]

On Fri, Dec 9, 2016 at 12:47 PM, Rich Alderson 
wrote:

> [1] For non-PDP10 programmers:  The original architecture of the PDP-6 and
> PDP-10 used an 18-bit (256KW) address space.  The KI-10 processor added
> a 22-bit pager and a concept of sections to the hardware.
>

As you say, the KI10 had 22-bit physical memory addressing, almost
identical to the "KI paging" of the later Model A KL10.  There were two
PTEs per 36-bit word in the page table, with the five of the 18 bits being
the APWSX properties, and the remaining 13 being a physical page number.
The 13-bit physical page number was concatenated with the offset into the
512-word page (low 9 bits of the virtual address) to get the 22-bit
physical address.

However, the KI10 did not have any "sections". Sections were introduced
with the Extended ("Model B", "KL paging") KL10.

RE: Flex Disc options for the HP 9825

[Rik Bos]

> -Oorspronkelijk bericht-
> Van: cctech [mailto:cctech-boun...@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

Re: Flex Disc options for the HP 9825

[Craig Ruff]

Excellent news!  I eagerly look forward to this so I can get my 9825T talking 
to my 9895A!  If you spin a PC board, I will be willing to purchase one or two 
if you end up with extras or are willing to coordinate an order.

Re: Flex Disc options for the HP 9825

[Curious Marc]

Fantastic! Can't wait for the info.
Marc

> On Dec 9, 2016, at 4:36 PM, Paul Berger  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.

Re: SGI Indigo, WTB Power supply? Burning smell?

[ethan]

After sniffing the PCBs for a minute or so like bomb dog looking for a burned 
resistor or cap I got to thinking that the PCBs are bigger than I 
remembered. Better than I remembered.


Found the fried component! A surface mount yellow rectangular capacitor 
mounted on the bottom of the CPU board, somewhat near the audio DAC 
section. I wonder if all the similar caps that are on the bottom should be 
replaced. Maybe one went bad, but if one went then the others might be at 
risk as well.


After removing the PSU to open it up, I found that it's the R4K model 
power supply (Yay!) and there doesn't seem to be anything fried in it.


One odd thing, and I can't remember my SGI enough. I get the TOD clock 
error on the Indigo, and I get no startup chime tune sound. It had kind of 
a sputtering tick from the speaker (perhaps the fried cap is in the audio 
section.) Anyone know if the chime should play before the time of day 
clock error?



--
Ethan O'Toole

Re: Megatek Series 7000 Graphics System?

[Toby Thain]

On 2016-12-10 3:58 AM, Holm Tiffe wrote:


Hi,

I've got a card cage full of cards that seems to be a Megatek Graphics
Subsystem. I've found a board with coaxial connectors that seems to be
the Video Output Board, a CPU build out of two stacked cards, one with 8
pcs. AM2901BC and some Memory..

One fo the card(stacks) has front connectors looking like Unibus (or
QBus).

There is no PSU attached to the card cage.

After googeling around I think the thing is related to a Megatek 7250
graphics Terminal mentioned here an there..but no pictures could be
found.

Is there soemone that has more informations about that thing?
The megatek is an a bad shape, Crystal oscillators are heavyly corroded
on the outside, it sat for 20+ years somewhere on the Attic.



Nice. I've seen a Megatek running, at Royal Melbourne Institute of 
Technology, Australia, circa 1982.


--Toby




I'll make some Pictures next week ..

Regards,

Holm

Happy DEC-10!

[Lars Brinkhoff]

Happy DEC-10, everyone!

As a gift, we offer some steaming hot, freshly baked bits.  Straight out
of the oven, here are over 80 PDP-10 programs built from source code.

http://github.com/PDP-10/its

Megatek Series 7000 Graphics System?

[Holm Tiffe]

Hi,

I've got a card cage full of cards that seems to be a Megatek Graphics
Subsystem. I've found a board with coaxial connectors that seems to be
the Video Output Board, a CPU build out of two stacked cards, one with 8
pcs. AM2901BC and some Memory..

One fo the card(stacks) has front connectors looking like Unibus (or
QBus).

There is no PSU attached to the card cage.

After googeling around I think the thing is related to a Megatek 7250
graphics Terminal mentioned here an there..but no pictures could be
found.

Is there soemone that has more informations about that thing?
The megatek is an a bad shape, Crystal oscillators are heavyly corroded
on the outside, it sat for 20+ years somewhere on the Attic.

I'll make some Pictures next week ..

Regards,

Holm

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