I told the person that they will get more $$ if they prepare in
advance to ship, etc. People don't care and /or are lazy sometimes.
b
On Thu, Jul 23, 2015 at 11:21 AM, Bill Sudbrink <wh.sudbrink at verizon.net> wrote:
>> I spoke with the person, told him it was historic, looked up some info
>> on the machine and when it was produced, etc. VERY surprised it sold
>> for $5. Total bargain.
>
> That's what "local pickup only" will do to an auction.
> There's a Vector MZ for 99 cents right now for the same reason.
>
> Bill S.
>
>
--
Bill
vintagecomputer.net
>
> On Dec 17, 2014, at 7:35 AM, Al Kossow wrote:
>
> > I should have one, somewhere.. Bear or Earl probably have one as well.
>
> Apparently I don't have an XY472, or at least one doesn't show in
> inventory. I was totally ready to jump in and save the day, too!
>
> ok
> bear.
I'll try to check tonight when I get home... spreadsheet says I have 8
Xylogics SMD controllers... have to see if any is an XY472.
Earl the Squirrel
In honour of the 30th anniversary. Anyone want this handbuch? In good
condition, some staining on front cover but no dog-ears or creases.
Free for the cost of postage from the Czech Republic.
--
Liam Proven ? Profile: http://lproven.livejournal.com/profile
Email: lproven at cix.co.uk ? GMail/G+/Twitter/Flickr/Facebook: lproven
MSN: lproven at hotmail.com ? Skype/AIM/Yahoo/LinkedIn: liamproven
Cell/Mobiles: +44 7939-087884 (UK) ? +420 702 829 053 (?R)
> From: Tothwolf
> How do you know those aluminum electrolytic capacitors are functioning
> just as good as they did when they were new? Unless you've tested them
> out of circuit ...
> ... aluminum electrolytic capacitors by their very electrochemical
> nature degrade as they age and as they are used.
I am way out of my knowledge range in this discussion, but here's something I
wanted to ask about: how do you reconcile this observation (assertion?) with
the observations from several people (e.g. the PDP-1 people) that they _have_
measured the electrolytics in their power supplies, and despite being N
decades old (where N ~= 5), they are _still_ within specs? If the very nature
of electrolytics mandates that they degrade, how are these still meeting
specs?
I'm very confused...
Noel
Previously I posted photos of a Zilog Z8-02 MPD running a copy of the
Z8671 BASIC subset ROM code on a breadboard. The Z8-02 was packaged in
a ceramic leadless QUIP package, and I have only one good QUIP socket,
so I made an adapter that the QUIP socket can plug into, which then
has a very wide 64-DIP footprint for ease of prototyping. The bottom
of the adapter has footprints for surface-mount decopling capacitors
very close to all of the QUIP socket pins; the SMT capacitors are
installed depending on the specifc chip for which the adapter is
configured.
Although the Z8-02 is totally unrelated to the Intel iAPX 432, this
served as validation that I can make a usable QUIP socket adapter.
The iAPX 432 General Data Processor consists of two chips, the 43201
instruction unit and the 43202 execution unit, both packaged in the
ceramic leadless QUIP. Since I only have one QUIP socket, I plan to
make sockets using pogo pins and a machined or 3d-printed frame. For
now, I have just wired up the 43201 on a breadboard in microcode ROM
dump mode, and captured the ROM contents using a logic analyzer.
Photos:
https://www.flickr.com/photos/22368471 at N04/sets/72157653865063443
The 43201 has 4K words of 16 bits of vertical microcode ROM, however
the top-level control is not done by the microcode ROM, but rather by
a bunch of PLAs and hardwired logic. Many of the simpler 432
instructions are executed without use of the microcode ROM at all.
Microcode routines are invoked in response to specific conditions or
more complex instructions, and the routine entry addresses come from
those PLAs, so it is fairly difficult to interpret the contents of the
microcode ROM. While I can identify many of the entry points, I only
have been able to determine what a few of them actually do, such as a
few of the floating point instructions, and one of the simplest object
instructions. However, eventually I hope that study of the ROM dump
will shed some light on a few dark corners of the architecture left
unspecified by the otherwise fairly comprehensive iAPX 432 General
Data Processor Architecture Reference Manual.
I have a design in progress for an iAPX 432 test system using a
MicroZed board. This is based on the Xilinx Zynq, which has ARM
Cortex-A9 processor hard cores as well as a substantial amount of FPGA
fabric. The MicroZed will plug into my board, which will have
level-shifters and such, as well as the QUIP sockets for the 43201 and
43202. The FPGA will be programmed to act as a memory controller for
the 432 packet bus, as well as a logic analyzer for both that bus and
the interchip bus used for microinstructions and status.
There is not known to be any surviving coherent release of iAPX 432
software, so I'm developing my own software from scratch. It is a
large task, because the iAPX 432 architecture is completely
object-oriented (implemented by the microcode and hardware), and there
have to be several dozen properly formed system objects in memory just
to execute the simplest program.
I expect that my first attempts to get the iAPX 432 to execute a code
image I have generated will result in failure. The 432 architecture
provides for a lot of software fault recovery, but if the system
objects are not properly set up for the fault condition, it will
assert the FATAL pin and halt. (This is the same concept as a double
bus fault on more conventional processors.) By studying the bus
activity leading up to the halt, I hope to be able to determine what
problem with the memory image led to the halt.
> From: Guy Sotomayor
> I haven't looked, but I think the Unibus and QBus are comparable in
> terms of pin count.
Well... the QBUS does have those shared address/data lines, so its 'raw'
count (i.e. number of wired-or broadcast bus lines) is somewhat lower (-16
data pins, but +4 address lines, plus various other differences).
Depending on the details that may, or may not, translate into a lower pin
count to the FPGA. E.g. if one has separate input and output pins for
address/data lines (one needs all 4 functions for doing both incoming slave
mode, and DMA), it can add up.
So, I noticed that on some QBUS cards DEC used a quad transceiver with
tri-state output (on the card side), the AM2908PC. It has separate tri-state
drive enable, and bus drive enable, pins. The FPGA we were looking at
supports bi-directional pins (i.e. tri-state output, plus input), so I
conceived the hack of tying the transceiver's input and output pins together,
and routing them into bi-directional pins on the FPGA. As long as one doesn't
turn on the tri-state drive and the QBUS drive enable at the same time
(forming a feedback loop at the transceiver chip), it _should_ work OK.
(Mandatory observation about theory and practise included at this point...)
So that reduces the number of pins needed by half. (Although I guess one
could pull the same hack with the UNIBUS, _iff_ the 2908 can work as a UNIBUS
transceiver; analog electrically, the two seem to be pretty identical.)
One can further observe that on the QBUS, A and D are shared, so one doesn't
need separate A and D pins. One cannot do that with the UNIBUS, since they
way DATO works, the A and D lines have to be driven at the same time (with
different values, of course).
Noel
> From: tony duell
> it's quite possible they started off at the top end of that range, have
> deteriorated over the years, and are still within spec. Of course
> nobody can prove that (unless there are records of the values meaured
> 50 years ago)
Well, I don't know about 50 years, but I know some of the restorations (where
people said they checked that their electrolytics were still withina spec)
were a while back, so _iff_ they have records of what they measured, it would
be interesting to see if there's any drift from then, to now. But I have no
idea what numbers they have, they'd have to speak to that.
> I have no idea what was measured. The capacitance value is not the
> whole story by any means. In fact the most important thing most of the
> time is ESR
Again, I have no idea what they measured, so they'd have to respond on that.
Noel
>
> Date: Mon, 20 Jul 2015 14:11:46 +0000
> From: tony duell <ard at p850ug1.demon.co.uk>
> Subject: RE: PDP 11 gear finally moved
> >
> > Replace - yes, *especially* if you don't have a big budget. Aluminum
> > electrolytic capacitors are CHEAP and easy to obtain. Replacement
> > semiconductors by comparison are expensive and can be quite difficult to
> > find.
>
The RICM ignored the sage advice from experts and reformed the
electrolytics in the PDP-12 that we are currently working on. This decision
was based on our past experience on other restorations, the lack of
replacements in the same physical size, and the very high cost of the
replacements. So far the system is behaving nicely.
We have had several spectacular failures of the AC caps with the
ferroresonant circuit in DEC power supplies. We regularly replace the AC
caps because they are available and inexpensive.
--
Michael Thompson
