- vcf-midatlantic - lists.vcfed.org

Re: [vcf-midatlantic] vcf-midatlantic Digest, Vol 77, Issue 24
by Michael Thompson 29 Oct '24

29 Oct '24

David, We are having similar issues with the newly acquired Straight 8 at the RICM. It is part of the first 50 built so there are some differences from later systems. FlipChips were physically damaged and some missing, the fragile plastic pivots on about 20 front panel switches were broken, and it hasn't been powered on for 50 years. We fixed the switch pivots, the power supply, replaced the missing FlipChips and started debugging. We actually got it to the point where it would run programs, but it has now deteriorated to the point where we can't load a RIM paper tape. I am happy that no one is hounding us to get it back in production. We are getting lots of help from PDP-8 experts like you, so we will eventually get it demonstrable. Like you, we have found many failed diodes that don't seem to affect operation. Robust design? On Tue, Oct 29, 2024 at 8:03 AM <vcf-midatlantic-request(a)lists.vcfed.org> wrote: > Date: Mon, 28 Oct 2024 21:58:17 -0400 > From: David Gesswein <djg(a)pdp8online.com> > Subject: [vcf-midatlantic] VCF straight 8 work at workshop > > Worked on the VCF straight 8 that was acting up again. It would load the > first instruction to execute when you hit the start key but didn't load > the > next instruction after updating the program counter. Kept reexecuting the > first instruction. > > TLDR: Found some signals that weren't quite right but fixing them didn't > help. Found actual bad diode that was causing the failure but then > diagnostics found another fault. Whike working on that memory stopped > working > when machine on for a while. Ran out of time to determine why so still not > usable. -- Michael Thompson

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Re: [vcf-midatlantic] Announcement: Administrative and Policy Changes
by Tony Bogan 29 Oct '24

29 Oct '24

We are, or were created as one in 2015, an extension/chapter/whathaveyou of VCF National. We don’t necessarily need to remain that, but that is what we are at the moment. Tony Bogan > On Oct 29, 2024, at 8:39 AM, Tony Bogan via vcf-midatlantic <vcf-midatlantic(a)lists.vcfed.org> wrote: > > > <mime-attachment>

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Mac 84 Video about the Swap Meet
by Christian Liendo 29 Oct '24

29 Oct '24

Terrifyingly Good Deals at the VCF Swap Meet! https://youtu.be/R9755DLjrfE?si=dTyRmdPewElB3XhH

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Re: [vcf-midatlantic] Announcement: Administrative and Policy Changes
by Jeffrey Brace 29 Oct '24

29 Oct '24

On Sun, Oct 27, 2024 at 18:11 Sentrytv via vcf-midatlantic < vcf-midatlantic(a)lists.vcfed.org> wrote: > I’m here. I thought VCF was chosen to compete with TCF. It was definitely not to compete with TCF. I was part of the founding. TCF is the Trenton Computer Festival and a once a year event started in 1976? in NJ. Vintage Computer *Festival* was started in 1997 in California. Vintage Computer *Federation* was started in 2016. I can’t recall the exact reason, but likely to match the acronym VCF which was the *Festival *as well as be global sounding and nature with Festivals around the world. The biggest problem as I see it is that people have trouble distinguishing between the *Festival* and the *Federation*. I have to explain to many people the difference between them. Vintage Computer Festival West and Vintage Computer Festival East are run by the Vintage Computer Federation. The other Festivals are independent. I have been to VCF West, VCF East, VCF MidWest, VCF SouthWest, VCF Pacific Northwest, World of Commodore, Trenton Computer Festival, HOPE, World Maker Faire and have had to explain the differences at each event. There are even people that confuse Trenton Computer Festival and Vintage Computer Festival. > > Sent from: > My extremely complicated, hand held electronic device. > > > On Oct 27, 2024, at 5:33 PM, Jeff Salzman via vcf-midatlantic < > vcf-midatlantic(a)lists.vcfed.org> wrote: > > > > The name MARCH was suggested because of its prior familiarity, and that > > there is already a BARCH for the Bay Area Retro Computing Hobbyists, > which > > is technically VCF Bay Area. > > > > BARCH and MARCH > > > > Another reason to stick with the naming convention is that it rolls off > the > > tongue better than saying a bunch of consonants, yet still maintaining a > > meaning as an acronym. > > > > Jeff Salzman > > > >> On Sun, Oct 27, 2024, 3:57 PM W2HX via vcf-midatlantic < > >> vcf-midatlantic(a)lists.vcfed.org> wrote: > >> > >> How about just VCFED-NJ people will generally know where New Jersey is > >> located. If, someday, another chapter is opened in, say North Carolina, > >> they can just call themselves VCFED-NC > >> > >> > >> 73 Eugene W2HX > >> My Youtube Channel: https://www.youtube.com/@w2hx/videos > >> > >> > >> -----Original Message----- > >> From: vcf-midatlantic <vcf-midatlantic-bounces(a)lists.vcfed.org> On > Behalf > >> Of Joshua Abraham via vcf-midatlantic > >> Sent: Friday, October 25, 2024 6:16 PM > >> To: vcf-midatlantic <vcf-midatlantic(a)lists.vcfed.org> > >> Cc: Joshua Abraham <jarvideo(a)gmail.com> > >> Subject: Re: [vcf-midatlantic] Announcement: Administrative and Policy > >> Changes > >> > >> Just my two cents, but I feel like Mid-Atlantic should be retired for a > >> more defined region name such as North East or New England to better > define > >> the center of the chapter's operations. > >> > >> The term "Mid- Atlantic" I have seen in other circles to be very broadly > >> defined at times from as far south as the Carolinas and as far north as > New > >> York State. > >> > >> That being said I think there would be a benefit in selecting a name > that > >> better aligns with many of the other regional groups official or > otherwise > >> for the sake of consistency to the layman. > >> > >> I know that technically Vcf does live within the mid Atlantic boundary, > >> but being on the outer edge, it may be best to focus on a more central > name. > >> > >> Who knows, another group could pop up between new Jersey and Georgia one > >> day. May as well plan for the future. > >> > >> Respectfully, Joshua. > >> > >> On Fri, Oct 25, 2024, 5:09 PM Sentrytv via vcf-midatlantic < > >> vcf-midatlantic(a)lists.vcfed.org> wrote: > >> > >>> Thomas and to all > >>> > >>> Are the items that you mentioned here (and others pending) going to be > >>> brought up at the Festivus meeting that we usually have in December > >>> and VCF members allowed to vote on it?( or sooner) I am sure that you > >>> and the others will keep us Informed. > >>> > >>> Mike Rosen > >>> > >>> Sent from: > >>> My extremely complicated, hand held electronic device. > >>> > >>>> On Oct 25, 2024, at 2:40 PM, Thomas G via vcf-midatlantic < > >>> vcf-midatlantic(a)lists.vcfed.org> wrote: > >>>> > >>>> We in the steering committee have been considering making a number > >>>> of changes to our operation, role, and focus for the past few weeks. > >>>> We feel that our operation and communication has not been as > >>>> effective as it > >>> could > >>>> be, given our stated goals, and are also considering certain changes > >>>> to > >>> the > >>>> broader aspects of VCF Mid-Atlantic, such as membership, elections, > >>>> and defining our role in relation to VCF National, largely in > >>>> response to feedback from VCF Mid-Atlantic members. One of the > >>>> changes we are considering, while largely inconsequential, is to > >> revive the name 'MARCH' > >>>> (short for 'Mid Atlantic Retro Computing Hobbyists') to replace the > >>> clunky > >>>> 'VCF Mid-Atlantic'. We are still in the deliberating process, but > >>>> one change worth reporting has already occurred - Jeff Salzman has > >>>> delegated the role of Steering Committee Chairman to Thomas > >>>> Gilinsky. The > >>> composition > >>>> of the steering committee has not changed aside from this. > >>>> > >>>> Further information will be made available as we finalize our > >> decisions. > >>> > >>> > >> > >

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MARCHing to the VCF of a different drummer ...
by Jeffrey Jonas 29 Oct '24

29 Oct '24

Having suffered the ambiguity of explaining VCF festival vs. federation vs VCF-mid-atlantic (formerly known as MARCH) I agree with the need for clarity. How about VCF-Jeff, VCF-Dave ... depending on the name majority :-) Be careful what you wish for, lest VCF-NJ become VCF region 1 like IEEE's "solution" to geography https://www.ieee.org/communities/regional-world-map.html

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VCF straight 8 work at workshop
by David Gesswein 29 Oct '24

29 Oct '24

Worked on the VCF straight 8 that was acting up again. It would load the first instruction to execute when you hit the start key but didn't load the next instruction after updating the program counter. Kept reexecuting the first instruction. TLDR: Found some signals that weren't quite right but fixing them didn't help. Found actual bad diode that was causing the failure but then diagnostics found another fault. Whike working on that memory stopped working when machine on for a while. Ran out of time to determine why so still not usable. Started browsing signals. PDP-8 signals are referred to as 0V and -3V. They actually are one diode drop below -3V. The F(1) signals which indicates the machine is in the fetch state was only going to about -1.8V. Normally this is caused by a leaky diode on logic being driven by the signal. Went through the schematics trying to find everywhere the signal went. Pulled 12 boards and tested diodes. Found and replaced one with high forward voltage but none measured low forward voltage indicating they are leaky. Reverse test would be better but components on the boards make some diodes read as leaky and hard to be sure you have gotten good connection through the surface oxides. Good diode and poor connection read the same on the meter. F(1) drives the light on the front panel through a drive transistor. Found that if I put a piece of tape on the edge connector to open that connection the signal level returned to proper. The manual doesn't have schematic for the front panel so need to figure that out. Much time spent and it didn't fix the problem. Will need to make measurements on my machine so I can compare with VCF and determine real cause of signal level issue. Suspect its not really the front panel but removing that load allowed signal to go to proper level. Looking at more signals found PA30 J output F set which sets the fetch flip flop also wasn't going as low as it should. I put a replacement S111 in and that fixed it. No change to symptoms. Later after I fixed the real problem I was going to swap the card back and see if it caused problems. I couldn't find a S111 card around. Wondered if my notes were a hallucination. Did find a R111 around but thought I had pulled a S111. The difference between the cards is the pull down resistors to -15V are changed from 7.5K on R111 to 3K on S111. This improves the fall time on the signal and gives more low drive (4mA vs 1.6 mA). The increased drive may be hiding a leaky diode. Don't have specifications for D-664 diode to know expected leakage. Typical small signals diodes are less than a microamp. I checked old pictures of the machine and PA30 had a R111. The early manual had R111 shown in the schematic but the card layout chart showed S111. The later manual had S111 in both locations. Next found spec cycle signal was at -1.4V. Checked cards signal goes to and found PA32 had a diode where the forward voltage measured .1V. Replaced diode and signal now had proper level and it started fetching instructions properly. Ran maindec-801-1-pm and it halted at 1062. This test was checking the proper return address got stored on an interrupt. Found the previous tests return address was at address 0. Single cycle stepping showed that it wrote the return address to location 4 instead of 0. The memory address register bit 9 didn't clear when it was supposed to. Pulled the R211 card and checked the diodes and found one with 1V forward drop and replaced it. Didn't fix it. At this point memory stopped working. All reads returned 0. Found if I turned the machine off for a while memory would operates for a while. Test still failed. Swapping in a spare R211 fixed the problem. The memory signals seemed to be operating normally when reads weren't working. The sense amplifier E pin didn't show a pulse. All memory locations and all bits don't work. All power supply voltages seemed reasonable and didn't change significantly between working and not working. Wasn't able to determine what the problem was before time to pack up.

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Re: [vcf-midatlantic] Announcement: Administrative and Policy Changes
by Jeff Salzman 28 Oct '24

28 Oct '24

The VCF swag is "VCF", and hasn't officially stood for VCF-MA swag. It will still be usable and sellable as sanctioned VCF events. The same swag was sold at VCF-W and VCF-MW. The only thing that may come to fruition under the MARCH name is that we order swag for MARCH as local chapter swag. On Mon, Oct 28, 2024, 7:43 PM Sentrytv via vcf-midatlantic < vcf-midatlantic(a)lists.vcfed.org> wrote: > Yeah > What about all that VCF swag? > > Sent from: > My extremely complicated, hand held electronic device. > > > On Oct 28, 2024, at 7:38 PM, David Riley via vcf-midatlantic < > vcf-midatlantic(a)lists.vcfed.org> wrote: > > > > On Oct 28, 2024, at 13:20, Jonathan Chapman via vcf-midatlantic < > vcf-midatlantic(a)lists.vcfed.org> wrote: > >> > >> > >>> > >>> the most enticing factor is consistency > >> > >> And that a lot of us still have MARCH shirts we can wear :P > > > > Indeed, I just did a shirt purge and found my old MARCH polo! Pleased to > say it’s held up well. > > > > > > - Dave > > > >

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Re: [vcf-midatlantic] Announcement: Administrative and Policy Changes
by CJ Reha 28 Oct '24

28 Oct '24

> What about all that VCF swag? The Vintage Computer Federation still exists and the events aren't being renamed, it's not really gonna go "obsolete" or anything. Take care, CJ On Mon, Oct 28, 2024 at 7:43 PM Sentrytv via vcf-midatlantic < vcf-midatlantic(a)lists.vcfed.org> wrote: > Yeah > What about all that VCF swag? > > Sent from: > My extremely complicated, hand held electronic device. > > > On Oct 28, 2024, at 7:38 PM, David Riley via vcf-midatlantic < > vcf-midatlantic(a)lists.vcfed.org> wrote: > > > > On Oct 28, 2024, at 13:20, Jonathan Chapman via vcf-midatlantic < > vcf-midatlantic(a)lists.vcfed.org> wrote: > >> > >> > >>> > >>> the most enticing factor is consistency > >> > >> And that a lot of us still have MARCH shirts we can wear :P > > > > Indeed, I just did a shirt purge and found my old MARCH polo! Pleased to > say it’s held up well. > > > > > > - Dave > > > >

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Re: [vcf-midatlantic] Announcement: Administrative and Policy Changes
by Thomas G 28 Oct '24

28 Oct '24

As has been mentioned several times in this thread already, there is an unnecessary amount of confusion caused by common use of the acronym "VCF" across the federation, the festival, and the club. To clarify - the name "Vintage Computer Federation" is not going away. All that's changing is the name of our particular club, which has continuously existed since 2004, and became a member of the nascent VCFed when that was formed in 2015. The Federation currently consists of two clubs - our own VCF Mid-Atlantic (formerly MARCH, and hosts of VCF east) and Bay Area Retro Computer hobbyists (hosts of VCF west). There are also a number of clubs outside the purview of the federation - the Atlanta Historical Computer Society (hosts of VCF Southeast), Chicago Classic Computing (hosts of VCF Midwest), the Seattle Retro-Computing Society (former hosts of VCF PNW), the Retro Computing Society of Rhode Island, etc. Out of all of these clubs, ours is the only one which has incorporated the name "VCF". We are not unique in that we host a festival, or in that we are a member of the federation, or in that we are a retro-computing hobbyist club. There is no good reason to keep "VCF" in our name, and keeping it serves only to guarantee further confusion as to where the club ends and the festival/federation begins. As for the specific use of the name "MARCH" to replace VCF-MA, the most enticing factor is consistency. Most of our core, regular members still informally use the term 'MARCH' to refer to the club, as well as many of the other members of Infoage - our home in meatspace. Not to mention, the name 'Mid-Atlantic Retro Computing Hobbyists' already aptly describes where we are located (Our core members hail from the Virginias, Maryland, Pennsylvania, Delaware, New Jersey, and New York - there is no regional term encompassing those states other than 'Mid-Atlantic') and what we are - Retro-Computing Hobbyists. There is no shame in having a hobby. The switch from "VCF-MA" back to "MARCH" would be quick, easy, and relatively painless compared to trying to come up with a new name that is just as apt and doesn't sacrifice the ability to be pronounced - and believe me, we have tried several times. Most of the results were quite vulgar. On Mon, Oct 28, 2024 at 11:24 AM Dan FitzGerald via vcf-midatlantic < vcf-midatlantic(a)lists.vcfed.org> wrote: > I'll take this point and counter it (although I personally don't like > the name MARCH): when I'm trying to talk about VCF Mid-Atlantic to > people, I often (accidentally) conflate VCF Mid-Atlantic (the group) > with VCF East (the event) and VCF (the umbrella organization). Heck -- > even in my head VCF is VCF is VCF, except that they really are three > different things. > > (I will second you, though, on "VCF Mid-Atlantic" being a sensible name > for the group as it regularly serves people from Virginia to > Connecticut) > > Regards, > Dan FitzGerald > They/Them or She/Her > Classical Computing Laboratory at IBM Poughkeepsie > http://www.vm.ibm.com/devpages/dfitzger > > > > -----Original Message----- > From: Tony Bogan via vcf-midatlantic <vcf-midatlantic(a)lists.vcfed.org> > Reply-To: vcf-midatlantic <vcf-midatlantic(a)lists.vcfed.org> > To: vcf-midatlantic <vcf-midatlantic(a)lists.vcfed.org> > Cc: Tony Bogan <thebogans(a)mac.com> > Subject: Re: [vcf-midatlantic] Announcement: Administrative and Policy > Changes > Date: 10/27/2024 05:57:51 PM > >

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Re: [vcf-midatlantic] Announcement: Administrative and Policy Changes
by Dan FitzGerald 28 Oct '24

28 Oct '24

I'll take this point and counter it (although I personally don't like the name MARCH): when I'm trying to talk about VCF Mid-Atlantic to people, I often (accidentally) conflate VCF Mid-Atlantic (the group) with VCF East (the event) and VCF (the umbrella organization). Heck -- even in my head VCF is VCF is VCF, except that they really are three different things. (I will second you, though, on "VCF Mid-Atlantic" being a sensible name for the group as it regularly serves people from Virginia to Connecticut) Regards, Dan FitzGerald They/Them or She/Her Classical Computing Laboratory at IBM Poughkeepsie http://www.vm.ibm.com/devpages/dfitzger -----Original Message----- From: Tony Bogan via vcf-midatlantic <vcf-midatlantic(a)lists.vcfed.org> Reply-To: vcf-midatlantic <vcf-midatlantic(a)lists.vcfed.org> To: vcf-midatlantic <vcf-midatlantic(a)lists.vcfed.org> Cc: Tony Bogan <thebogans(a)mac.com> Subject: Re: [vcf-midatlantic] Announcement: Administrative and Policy Changes Date: 10/27/2024 05:57:51 PM

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