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<?xml version="1.0" encoding="utf-8"?>
<rss version="2.0"><channel><title>fritzm.github.io - PDP-11</title><link>https://fritzm.github.io/</link><description></description><lastBuildDate>Fri, 01 Sep 2023 00:00:00 -0700</lastBuildDate><item><title>GT40 Terminal II: Lunar Lander</title><link>https://fritzm.github.io/gt40-2.html</link><description><p><em>[Continuation of restoration work on a DEC GT40 graphic display terminal; part one
<a href="https://fritzm.github.io/gt40.html">here</a>.]</em></p>
<p>At this point, Scott had taken over the restoration work as I had had to leave town for work. We consulted a
few times via IMs and video calls over the next couple weeks; the following …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Fri, 01 Sep 2023 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2023-09-01:/gt40-2.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>GT40 Terminal</title><link>https://fritzm.github.io/gt40.html</link><description><p>A while ago my friend Scott approached me with an idea to collaborate on restoration of a DEC GT40 graphic
display terminal of unknown status, belonging to a third collector friend of ours; the idea was to restore the
machine to working order for exhibition at the various summer/fall …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Mon, 21 Aug 2023 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2023-08-21:/gt40.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>BASIC-11 under RT11</title><link>https://fritzm.github.io/rt11-basic.html</link><description><p>I figured it might be fun to play around a little bit with BASIC-11 under RT11 on the newly-restored
PDP-11/34. If I got that working, it could also be included on the RK05 RT11 disk image that I use regularly
for demos on the larger PDP-11/45.</p>
<p>The first …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sun, 15 Aug 2021 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2021-08-15:/rt11-basic.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>Unibone</title><link>https://fritzm.github.io/unibone.html</link><description><p>I have been keeping an eye on Jörg Hoppe's interesting <a href="http://retrocmp.com/projects/unibone">Unibone project</a>
for some time -- it is a general-purpose Unibus device emulator and diagnostic tool, built around a
<a href="https://beagleboard.org/black">BeagleBone Black</a> compute module running embedded real-time Linux. The
PDP-11/34 restoration project finally provided enough impetus for me to pull the …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Wed, 24 Mar 2021 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2021-03-24:/unibone.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/34</title><link>https://fritzm.github.io/1134.html</link><description><p>This spring I worked on repair/restoration of a friend's PDP-11/34. The system was in fairly good shape, but
missing a few bits and pieces and with the usual sorts of issues for 45-year-old kit. Started per usual with
disassembly, cleaning, and inspection. The BA11-K chassis was in pretty …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Tue, 09 Mar 2021 00:00:00 -0800</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2021-03-09:/1134.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: Reversing a vintage DL11 hack</title><link>https://fritzm.github.io/dl11-bodge.html</link><description><p>I recently had need to assess and repair several DL11 serial interfaces in my stock of spares. One of these
had had some sort of end-user hack applied; in the course of putting the board back to factory condition, I
did some analysis of the hack and its intended purpose …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Fri, 27 Nov 2020 00:00:00 -0800</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2020-11-27:/dl11-bodge.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: Some more floating point trouble</title><link>https://fritzm.github.io/fp11-again.html</link><description><p><em>[A catch-up article, documenting events of April/May 2020]</em></p>
<p>In late April, I offered to give a video demonstration of the '11/45 to some interested work colleagues. Since
I hadn't had it on in a while, I fired it up to make sure everything was still in working order …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sat, 21 Nov 2020 00:00:00 -0800</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2020-11-21:/fp11-again.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: V6 Unix Troubleshooting, Part II</title><link>https://fritzm.github.io/unix-v6-trouble-2.html</link><description><p><em>[A catch-up article, documenting discoveries of Feb 2019]</em></p>
<p>In early 2019, I made a V6 Unix pack from the Ken Wellsch tape image, as mentioned in <a href="https://fritzm.github.io/unix-and-ms11.html">this blog
entry</a>. It booted on my machine, but dumped core on the first <code>ls</code> in single-user
mode, or as soon as I did …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sun, 25 Oct 2020 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2020-10-25:/unix-v6-trouble-2.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: V6 Unix Troubleshooting</title><link>https://fritzm.github.io/unix-v6-trouble-1.html</link><description><p><em>[A catch-up article, documenting discoveries of Jan/Feb 2019]</em></p>
<p>In early 2019, I made a V6 Unix pack from the Ken Wellsch tape image, as mentioned in <a href="https://fritzm.github.io/unix-and-ms11.html">this blog
entry</a>. It booted on my machine, but dumped core on the first <code>ls</code> in single-user
mode, or as soon as I …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sat, 24 Oct 2020 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2020-10-24:/unix-v6-trouble-1.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: ECOs</title><link>https://fritzm.github.io/ecos.html</link><description><p><em>[A catch-up article, documenting discoveries of Jan/Feb 2019 and some additional research while writing
up.]</em></p>
<p>Okay, per last article, specifics of parity-handling on my CPU indicate that it is missing several significant
ECOs. I spent some time seeing if I could dig up and/or puzzle out more details …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sun, 07 Jun 2020 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2020-06-07:/ecos.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: Parity error handling</title><link>https://fritzm.github.io/parity-handling.html</link><description><p><em>[A catch-up article, documenting events of Jan/Feb 2019.]</em></p>
<p>At the end of the previous article, a bunch of repairs had been made to my MS11-L memory board. The
associated MAINDEC diagnostic ZQMC was able to run cleanly <em>but only with parity tests disabled</em>. When parity
tests were enabled, the …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Mon, 25 May 2020 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2020-05-25:/parity-handling.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: V6 Unix attempts & MS11-L repairs</title><link>https://fritzm.github.io/unix-and-ms11.html</link><description><p>Following up on Noel's suggestion, I decided to give V6 Unix a try to see how it fared in comparison to the
problems seen with RSTS/E V06C. I recently scored an additional RK05 pack from eBay, and decided to try and
use that so I could keep my current …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Mon, 21 Jan 2019 00:00:00 -0800</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2019-01-21:/unix-and-ms11.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: RSTS/E V06C attempts</title><link>https://fritzm.github.io/rsts.html</link><description><p>Okay, back in action after replacing the failed nand at B26 in the RK11-C. MAINDEC ZRKK now passes reliably.
Wish I'd been able to get to the bottom of this at the show, but it was really hard to effectively debug on
the floor there while the show was in …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Mon, 07 Jan 2019 00:00:00 -0800</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2019-01-07:/rsts.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45 Behaving Badly</title><link>https://fritzm.github.io/behaving-badly.html</link><description><p>Wow, a year to the day since the previous post here! Not a lot of PDP-11 work this past year, with lots of
other stuff like home improvements going on, but a few things worth catching up on here.</p>
<p>Mainly, I got brave this past year and decided to actually …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sun, 09 Dec 2018 00:00:00 -0800</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2018-12-09:/behaving-badly.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: LA30 repair IV</title><link>https://fritzm.github.io/la30-4.html</link><description><p>Received replacement components for the blown G380 solenoid driver channel. After this repair, all pins are
firing and printing correctly. Calibrated left margin. Checked pin drive signal, which was within
specifications and required no adjustment.</p>
<p>Went to check carriage return pulse timing calibrations, but as it turns out the G396 …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sat, 09 Dec 2017 00:00:00 -0800</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2017-12-09:/la30-4.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: LA30 repair III</title><link>https://fritzm.github.io/la30-3.html</link><description><p>Digging in on the flip-flops identified as potentially problematic in the previous post, found that E5 had
failed. Pulled, socketed, and replaced; character generator now correctly clocks all five character columns:</p>
<p><img style="display:block; margin-left:auto; margin-right:auto" src="/images/pdp11/la30-chargen-clock-
trace-fixed.jpg" title="LA30 character generator clocking trace after repair. Runs correctly to five character columns"/></p>
<p>After this repair, characters were printing full width, but two problems remained: about half of the
characters printed in …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sat, 02 Dec 2017 00:00:00 -0800</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2017-12-02:/la30-3.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: LA30 repair II</title><link>https://fritzm.github.io/la30-2.html</link><description><p>Okay, first thing to debug today is the ready light. This is lit by RDY LITE L, pin A16D2 (lower right of
sheet M7721-0-1 in the LA30 engineering drawings). Logic probe showed this was correctly asserted low. Pulled
the lamp and checked it with bench supply, and it checked fine …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sun, 26 Nov 2017 00:00:00 -0800</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2017-11-26:/la30-2.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: LA30 repair</title><link>https://fritzm.github.io/la30-repair.html</link><description><p>Once again its been a little while since I've had to work on PDP-11 stuff or put any updates here; the <a href="https://www.lsst.org">day
gig</a> has been pretty intense lately.</p>
<p>Recent efforts have been focused on restoration of an LA30 printing terminal. This was really filthy
(including a mouse nest, yuck) so …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sat, 25 Nov 2017 00:00:00 -0800</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2017-11-25:/la30-repair.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: VT52 Keyboard Repair</title><link>https://fritzm.github.io/vt52-keyboard.html</link><description><p>The VT52 had a broken ESC key, and with RT-11 up and running I was motivated to dig in and fix it (you need
that ESC key if you are going to run the K52 editor). Pulling the keycap and giving things a look over, the
leaf contacts and the …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sat, 15 Jul 2017 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2017-07-15:/vt52-keyboard.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: Data Recovery</title><link>https://fritzm.github.io/data-recovery.html</link><description><p>Okay, the system is working well enough now to start attempting recovery and archive of the dozen or so RK05
packs that I have on-hand. These were all obtained (along with the RK05 drives, controller and power supply)
in a surplus auction downstream of Stanford's Hansen Experimental Physics Lab, sometime …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sun, 09 Jul 2017 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2017-07-09:/data-recovery.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: First RT-11 Boot From Disk!</title><link>https://fritzm.github.io/rt11-boots.html</link><description><p>Not much technical in this post, except the big ticket news: after all the recent repairs and generating a
fresh RT-11 pack <strong>RT-11 BOOTS FROM DISK!</strong></p>
<p>It's been a very long road getting here, but the machine finally has a working, full-featured, operating
system, capable of supporting self-hosted program development …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Thu, 06 Jul 2017 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2017-07-06:/rt11-boots.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: M9301 Troubles</title><link>https://fritzm.github.io/m9301-troubles.html</link><description><p>After a lot of recent progress with the RK11, suffered a setback: after trying once again to image
a fresh RT-11 pack, the machine began to behave erratically at boot. Sometimes the boot monitor would run
fine, sometimes it would run for a while and then take a machine exception …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Tue, 04 Jul 2017 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2017-07-04:/m9301-troubles.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: RK11 VII</title><link>https://fritzm.github.io/rk11-7.html</link><description><p>Okay, back from travel and picked up the thread on the RK11 interrupt problem this weekend. Put the KM11 in
the first slot on the RK11 which allows to monitor interrupt request. An interrupt can be very easily
generated from the front panel by writing bit 6 (Interrupt on Done …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sun, 25 Jun 2017 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2017-06-25:/rk11-7.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: RK11 VI - "Pole" and Interrupt Issues</title><link>https://fritzm.github.io/rk11-6.html</link><description><p>Replaced the failed 7401 in the RKDA to RKDB data path, and verified that the RKDB stuck bit 11 problem was
fixed. Ran the system for another couple hours to rewrite a fresh RT-11 pack, then another problem developed:
read operations would successfully obtain the bus, but would never complete …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Thu, 08 Jun 2017 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2017-06-08:/rk11-6.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: RK11 V - Checksum issues</title><link>https://fritzm.github.io/rk11-5.html</link><description><p>Decided to use the disk utilities provided in PDP11GUI to write a fresh RT-11 pack. PDP11GUI successfully
assembled and downloaded a driver, then took a little under 2 hours to download the pack image over the
console serial line and write the pack without indicating any errors.</p>
<p>The resulting pack …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sun, 21 May 2017 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2017-05-21:/rk11-5.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: CPU debug VI - RK11 NPRs and first disk boot!</title><link>https://fritzm.github.io/cpu-debug-6.html</link><description><p>Took a little of time to sort through BC11 cables to find a good one for drive interfacing, but in the end I
found one that worked okay and got the seek tester code from the previous post working reliably. At this
point I mounted one of the recently cleaned …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sun, 14 May 2017 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2017-05-14:/cpu-debug-6.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: RK05 II - Head Load and Servo Calibration</title><link>https://fritzm.github.io/rk05-2.html</link><description><p>Okay, disassembled and cleaned a few RK05 cartidges, following advice from the vcfed forum and cctalk
mailing list (cleanroom gloves and wipes, 99% anyhydrous isoprop). Was surprised to find foam inside
the hub on the disks (see pic below) but folks on vcfed advise that it is high-density polyeurethane
and …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sun, 09 Apr 2017 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2017-04-09:/rk05-2.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: RK11 IV</title><link>https://fritzm.github.io/rk11-4.html</link><description><p>A quick note: rejumpered a spare M105 address decoder, and swapped it in for the one that was in the RK11. SSYN waveform is greatly improved (see before/after shots below), so looks like a bad driver on
the original M105.</p>
<p><a href="https://fritzm.github.io/images/pdp11/rkcs-fixed.jpg"><img src='/images/pdp11/rkcs-fixed_thumbnail_tall.jpg'/></a>
<a href="https://fritzm.github.io/images/pdp11/rkcs-really-fixed.jpg"><img src='/images/pdp11/rkcs-really-fixed_thumbnail_tall.jpg'/></a></p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sat, 01 Apr 2017 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2017-04-01:/rk11-4.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: RK05</title><link>https://fritzm.github.io/rk05.html</link><description><p>Started going through the two RK05 drives. Lots of work to remove and clean up all the decaying foam.
Replaced the emergency head retract NiCd battery packs on both units. They were both slightly leaky, but
luckily neither had made a big mess.</p>
<p>Air filter elbows are intact on both …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sun, 19 Mar 2017 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2017-03-19:/rk05.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: RK11 III</title><link>https://fritzm.github.io/rk11-3.html</link><description><p>Okay, the M9202 bus jumper arrived, and like the 2-foot BC11 cable, the occasional timeouts go away when this
is installed. Hantek digital scope also arrived, so I decided to throw it on the backplane for a closer
look at the SSYN and timeout signals. The results were pretty interesting …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sun, 26 Feb 2017 00:00:00 -0800</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2017-02-26:/rk11-3.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: RK11 II</title><link>https://fritzm.github.io/rk11-2.html</link><description><p>Okay, moving on with the RK11-C debug, the following bit of test code is modeled after that part of the
ZRKJE0 diagnotic that is trapping out:</p>
<table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre> 1
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24 …</pre></div></td></tr></table></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Mon, 20 Feb 2017 00:00:00 -0800</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2017-02-20:/rk11-2.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: RK11</title><link>https://fritzm.github.io/rk11.html</link><description><p>Finished up the cleanup and rebuild of the H720E for the RK11-C controller: reformed the big electrolytics
over a couple of days, and swapped out the tantalum filters on the regulator board (one of which had started
to leak) for some replacements. Tantalums of the correct form and value are …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sun, 29 Jan 2017 00:00:00 -0800</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2017-01-29:/rk11.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: Diagnostics XIV - CPU, MMU, FPU Complete!</title><link>https://fritzm.github.io/diagnostics-14.html</link><description><p>Okay, after socketing in the replacement 74H10 and reseating a few boards, the output from the floating
point diagnostic now looks correct:</p>
<p><span style="font-size: x-small; font-family: monospace; white-space: pre; display: block; line-height: normal; font-weight: bold;">................ ................ ................ ................ .........11..... .........11..... .........11..... .........11.....
................ ................ ................ ................ ..........11.... ..........11.... ..........11.... ..........11....
................ ................ ................ ................ ...........11... ...........11... ...........11... ...........11...
................ ................ ................ ................ ............11.. ............11.. ............11.. ............11..
................ ................ ................ ................ .............11. .............11. .............11. .............11.
................ ................ ................ ................ ..............11 ..............11 ..............11 ..............11
................ ................ ................ ................ ...............1 1..............1 1 …</span></p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Mon, 16 Jan 2017 00:00:00 -0800</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2017-01-16:/diagnostics-14.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: Diagnostics XIII - FP11 FPU, cont.</title><link>https://fritzm.github.io/diagnostics-13.html</link><description><p>Have been looking into the FP11 MOD problem in spare moments of the past few weeks, but haven't written up
an account of the progress, so this will be a bit of a catch-up article.</p>
<p>Having now studied the design of this thing in more depth, there are a few …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Thu, 24 Nov 2016 00:00:00 -0800</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2016-11-24:/diagnostics-13.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: Diagnostics XII - FP11 FPU, cont.</title><link>https://fritzm.github.io/diagnostics-12.html</link><description><p>Some spare 74194 arrived in the mail; popped one in to the socket I had prepared at E15 on the FRL board,
and the FP add/subtract problem is fixed. The following FP11 diagnostics now pass:</p>
<style>
.diaglist { display: inline; border-collapse: collapse; margin-right: 1em; }
.diaglist caption { font-weight: bold; }
.diaglist tr:nth-child …</style></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sun, 30 Oct 2016 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2016-10-30:/diagnostics-12.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: Diagnostics XI - FP11 FPU, cont.</title><link>https://fritzm.github.io/diagnostics-11.html</link><description><p>Wrote some small test programs to investigate FP add/subtract. Turns out that single-precision add/subtract
works fine, but double-precision results come back with some erroneous bits set in the fraction.
Here's the test code I ended up using for troublshooting -- when executed on my machine, bits 24 and 25 …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sun, 23 Oct 2016 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2016-10-23:/diagnostics-11.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: Diagnostics X - FP11 FPU, cont.</title><link>https://fritzm.github.io/diagnostics-10.html</link><description><p>Okay, here's the dig in on the FP11 STST diagnostic failure. As detailed previously, I'd been seeing an
incorrect FEC after executing a small test program to generate a minus-zero condition. I'd verified that
the microcode sequence was per expectation, and that the correct FEC was being stored and retrieved …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sat, 01 Oct 2016 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2016-10-01:/diagnostics-10.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: H720E teardown and inspection</title><link>https://fritzm.github.io/h720e-teardown.html</link><description><p>Started in on the H720E power supply that is part of RK05 storage system. Just initial teardown, cleaning, and
inspection for obviously failed parts. Looks pretty good, though there is a lot of dust and grime because this
unit lost its top cover plate somewhere over the years (I'll have …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sun, 18 Sep 2016 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2016-09-18:/h720e-teardown.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: Diagnostics IX - FP11 FPU, cont.</title><link>https://fritzm.github.io/diagnostics-9.html</link><description><p>Did a lot of reading on the FP11 design. A few interesting notes that are buried in the maintenance manual:</p>
<ul>
<li>
<p>When debugging FP11 microcode with a KM11 in single-microstep mode, the 11/45 front panel microcode display shows
the address of the <em>next</em> microinstruction, NOT the current microinstruction. This is …</p></li></ul></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sat, 10 Sep 2016 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2016-09-10:/diagnostics-9.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: Diagnostics VIII - FP11 FPU</title><link>https://fritzm.github.io/diagnostics-8.html</link><description><p>Slotted in FP11 spares that I hadn't tried previously, and this has produced some improved results -- returning to
diagnostic CKBME0 (11/45 traps) this now passes with the floating point installed. Additionally, diagnostic
CFPAB0 passes.</p>
<p>CFPBB0 and CFPCD0, however, are failing. Unfortunately, the source code for these is not available …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sat, 03 Sep 2016 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2016-09-03:/diagnostics-8.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: Diagnostics VII - KT11 MMU</title><link>https://fritzm.github.io/diagnostics-7.html</link><description><p>Moving on to the KT11 MMU: running the first diagnostic in the CKT suite, got error reports at 010340, 010560, and
011000. Consulted the diagnostic listings, and these particular tests have to do with D-space translations from
kernel, supervisor, and user modes. The D-space logic is largely on module SSR …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sat, 13 Aug 2016 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2016-08-13:/diagnostics-7.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: Diagnostics VI - GRA ALU PROM repair</title><link>https://fritzm.github.io/diagnostics-6.html</link><description><p>Data I/O Series 22 PROM programmer from eBay showed up, as well as some unprogrammed Signetics 82S123.
Punched in the subsidiary ALU control ROM contents from the listing on GRAK in the 11/45 engineering drawings
and burnt a new PROM. Put a socket and the new PROM in …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sun, 07 Aug 2016 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2016-08-07:/diagnostics-6.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: Diagnostics V - D0AA0-D0MA0, CKBOA0</title><link>https://fritzm.github.io/diagnostics-5.html</link><description><p>The day gig has been keeping me pretty busy for the last couple of weeks, but had some time to work on the PDP-11
again this weekend, so here's an update.</p>
<p>Looking a little deeper at the diagnostics database over on retrocmp.com, I realized that I had skipped the …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sun, 31 Jul 2016 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2016-07-31:/diagnostics-5.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: Diagnostics IV - CKBME0</title><link>https://fritzm.github.io/diagnostics-4.html</link><description><p>Some progress with the CKBME0 diagnostic mentioned previously. It seems the concern with how the test behaves wrt.
preconditions of the serial interface was well founded.</p>
<p>In order to debug more easily, I extracted the failing test and built a small loop around it, with a pass counter
and display …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sun, 17 Jul 2016 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2016-07-17:/diagnostics-4.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: VT52 repair</title><link>https://fritzm.github.io/vt52-repair.html</link><description><p>Replacement oscillator arrived for the VT52, so spent some time getting it back going again. Things got <em>much</em> better
with a stable timing chain, but some glitchiness remained -- tracked this down to the socketed microcode ROMS which
just required a reseat.</p>
<p>Here you can see the new oscillator fitted (silver …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sat, 16 Jul 2016 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2016-07-16:/vt52-repair.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: Diagnostics III - CKBME0</title><link>https://fritzm.github.io/diagnostics-3.html</link><description><p>Okay, digging into the CKBME0 traps diagnostic now in more detail. Here I've transcribed the source of the failing
test from the older available diagnostic listing, then re-assembled it at the address matching the more modern
binary. This makes it a little easier to follow along while debugging the newer …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sat, 09 Jul 2016 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2016-07-09:/diagnostics-3.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: Diagnostics II</title><link>https://fritzm.github.io/diagnostics-2.html</link><description><p>Investigated some of the halted diagnostics a bit today. CKBGB0 (SPL instruction test) was halting at 001404.
Looking at the sources, the diagnostic was waiting at this point for a transmit interrupt from the DL11 that didn't
seem to be arriving. Some troubleshooting turned up that the vector address on …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Mon, 04 Jul 2016 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2016-07-04:/diagnostics-2.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: Diagnostics with PDP11GUI</title><link>https://fritzm.github.io/diagnostics.html</link><description><p>Okay, now that serial is straightened out, on to running diagnostic tests via PDP11GUI. PDP11GUI itself, as well as
a thorough and useful database of DEC diagnostic programs, are available at <a href="http://www.retrocmp.com/tools">http://www.retrocmp.com/tools</a>.</p>
<p>Since my home computer is a MacBook, I had intended to run PDP11GUI under …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sun, 03 Jul 2016 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2016-07-03:/diagnostics.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: Serial console and backplane SPC slots</title><link>https://fritzm.github.io/serial-console.html</link><description><p>Hit a snag on the way to getting PDP11GUI hooked up: while the M9301 console emulator was working fine with the VT52,
I could not get serial communication to my laptop (MacBook Pro + Keyspan USA-19HS USB serial) to work as expected. Some
detective work showed that the voltages from the …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sun, 26 Jun 2016 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2016-06-26:/serial-console.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: Running the M9301 console emulator</title><link>https://fritzm.github.io/m9301-running.html</link><description><p>Replacement DRAMs showed up. Pulled and replaced the two faulty ones on the MS11. Pic below -- you can see the
replacements are socketed, and are the TI parts instead of the original ITT. Full address space is working now! Now
that bank 0 is repaired, trap vectors can conceivably work …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Thu, 23 Jun 2016 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2016-06-23:/m9301-running.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: CPU debug V -- chasing lights!</title><link>https://fritzm.github.io/cpu-debug-5.html</link><description><p>Tracked down the source of the inverted result after register-to-register move problem on GRA: outputs of the
subsidiary ALU control ROM E74 on pins 6 and 7 are floating. Will need some closer inspection to determine if this
is a board fault or a chip fault. In the meantime, I …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sun, 19 Jun 2016 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2016-06-19:/cpu-debug-5.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: MS11-L debug</title><link>https://fritzm.github.io/ms11-debug.html</link><description><p>After addressing the -15V problem on the MS11, most of the bad behaviors seem to have cleared up except a stuck (on)
bit 6 in the first 16K words of address space (000000-077776). Hooked up the new logic analyzer, and it has been very
useful in troubleshooting the board -- can …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sat, 18 Jun 2016 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2016-06-18:/ms11-debug.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: MS11-L and CPU debug IV</title><link>https://fritzm.github.io/cpu-debug-4.html</link><description><p>Made some progress on the inverted result after register-to-register move problem: with the help of the KM11, extender
card, and a logic probe I was able to track down that signal ALUM L coming onto the DAP is not asserted when it should
be for a MOV instruction. This means …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sun, 12 Jun 2016 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2016-06-12:/cpu-debug-4.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: KM11 replica and CPU debug III</title><link>https://fritzm.github.io/cpu-debug-3.html</link><description><p>Executing a few instructions</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sat, 11 Jun 2016 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2016-06-11:/cpu-debug-3.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: CPU debug II</title><link>https://fritzm.github.io/cpu-debug-2.html</link><description><p>Basic front panel functionality</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sun, 05 Jun 2016 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2016-06-05:/cpu-debug-2.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: Power fixes and CPU debug</title><link>https://fritzm.github.io/power-fixes.html</link><description><p>Connected up the aforementioned red wire hack to the new power harness, and verified +5V to slots 10 through
15. Console is no longer all address and data lights on, but basic console load address / examine / deposit
operations are still not working. A random assortment of address lines seem stuck …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Mon, 30 May 2016 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2016-05-30:/power-fixes.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: Initial Power On!</title><link>https://fritzm.github.io/initial-power-on.html</link><description><p>Hold breath; turn key...</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sun, 08 May 2016 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2016-05-08:/initial-power-on.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: Power Harness, continued</title><link>https://fritzm.github.io/power-harness-2.html</link><description><p>Power harness finished and dressed</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sat, 23 Apr 2016 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2016-04-23:/power-harness-2.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: Power Harness</title><link>https://fritzm.github.io/power-harness.html</link><description><p>Starting a rebuild from scratch</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sun, 17 Apr 2016 00:00:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2016-04-17:/power-harness.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: Some parts from eBay</title><link>https://fritzm.github.io/ebay-parts.html</link><description><p>Expansion backplane, memory card, and diode-matrix ROM</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sat, 09 Apr 2016 11:25:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2016-04-09:/ebay-parts.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: VT52</title><link>https://fritzm.github.io/vt52.html</link><description><p>Cleanup and character generator dump</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sun, 03 Jan 2016 20:17:00 -0800</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2016-01-03:/vt52.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: CPU Backplane and logic</title><link>https://fritzm.github.io/backplane-and-logic.html</link><description><p>Slotting cards and bloody knuckles</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Fri, 03 Jul 2015 14:56:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2015-07-03:/backplane-and-logic.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: H742s and front panel</title><link>https://fritzm.github.io/panel-and-742s.html</link><description><p>Starting to look like a real PDP-11!</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sun, 21 Jun 2015 18:14:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2015-06-21:/panel-and-742s.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: AC power and cooling</title><link>https://fritzm.github.io/fans-and-h742s.html</link><description><p>Spent a lot of time over a couple weekends cleaning and reconditioning all the muffin cooling fans for the CPU
cabinet and power supplies. As you can see in the photo below, there are a lot of these! All reassembled
now, and wired along with the back-of-cabinet power distribution board …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sun, 07 Jun 2015 14:15:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2015-06-07:/fans-and-h742s.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: H742 power control boards</title><link>https://fritzm.github.io/power-controllers.html</link><description><p>Found a little time to clean up and go through the power control boards for the H742 supplies. They are
looking pretty good. Even the big electrolytics seem fine on first look. These things were built with very
high quality components, and they really seem to last and last.</p>
<p><img src='/images/pdp11/pwr-ctrls_thumbnail_tall.jpg' title='H742 power controller boards' onclick='pswipe("pdp11",8);'/></p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sat, 23 May 2015 16:30:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2015-05-23:/power-controllers.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: Teardown and corrosion remediation</title><link>https://fritzm.github.io/corrosion.html</link><description><p>Had a little more time to work on the PDP-11 this weekend. Mostly going after some corrosion on the CPU
cabinet and H742 power supplies. Tore these down, sanded down the corroded bits, then hit with a satin finish
Rustoleum rattle-can which dries to a reasonable approximation of the original …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sat, 11 Apr 2015 18:45:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2015-04-11:/corrosion.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: 861 AC power control</title><link>https://fritzm.github.io/861.html</link><description><p>Well, might as well start at the beginning with the AC power system, so here's the 861 power control. In very
good shape for some 40 year old kit! The neon indicator lamps have gone, so I sourced the modern equivalent
and put them on order. Everything else is tight …</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sun, 29 Mar 2015 10:35:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2015-03-29:/861.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item><item><title>PDP-11/45: Begin Again</title><link>https://fritzm.github.io/begin-again.html</link><description><p>Getting started on a PDP-11/45 restoration project</p></description><dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fritz Mueller</dc:creator><pubDate>Sun, 15 Mar 2015 18:45:00 -0700</pubDate><guid isPermaLink="false">tag:fritzm.github.io,2015-03-15:/begin-again.html</guid><category>PDP-11</category><category>Retro-Computing</category><category>PDP-11</category></item></channel></rss>