test-drb

test-drb@ccmp.vtda.org

101090 discussions

by marc.verdiell＠gmail.com

Thanks Chuck. Looks like you are on to something, I'll search in this direction. Unlikely it has anything to do with the disks themselves, which were blank. The 500 kHz write signal present on the connector just doesn't make it to the head, whereas the 300 kHz does. On the other handm something along what Chuck suggests could create this exact problem. I'll let you know how it goes. I am aware of the narrow track problem of 360k written by HD drives, so I have other native 360k DD drives for that purpose. For now I just want my HD drive to behave as one ;-) >At high density, have you taken a good look at pin 2 of the floppy >interface? Have you checked to see if pin 2 is configured (via jumpers) >as "density select"? Various drives have different jumperings for >pins 2 and 34 (and sometimes 4). For example, I deal with some Japanese >CNC gear that uses pin 2 for disk change and pin 34 for read (and pin 4 >for "in use". >--Chuck >> So I tried to force formatting in DOS at 360k, and sure enough it >> worked! I can then read the diskette back, write on it, etc... And of >> course it failed formatting at 1.2 Mb. But the drive (Chinon FR-506) >> is a 1.2M one, and reads fine at 1.2M! Any clue? Is there a drive >> setting that would prevent it to write at high density but let it do >> at low density?

10 years, 10 months

MIPS systems available...

by lbickley＠bickleywest.com

Weirdstuff recently received the following: (2) Magnum 4000SC-50 mips systems (2) RS 2030 mips systems Look clean (from the outside)... Contact Jim if you're interested in them. Usual disclaimer: I have no relationship with Weirdstuff other than as a client. I receive no remuneration for posting this. I do a weekly "tour" of their facilities to find vintage gear. Cheers, Lyle -- 73 AF6WS Bickley Consulting West Inc. http://bickleywest.com "Black holes are where God is dividing by zero"

10 years, 10 months

5.25 floppies that read but don't write

by marc.verdiell＠gmail.com

Following Chuck's advice, I scoped out the pin 22 and 24 (write data and write gate) on the floppy, and they looked fine. Then being curious, I managed to figure out what the write wire for Head 0 was. And I discovered I got nice matching writing pulses at 300 kHz (formatting at 360k density), but none at 500 kHz (1.2 Mb density). Results posted here: http://www.vintage-computer.com/vcforum/showthread.php?43874-5-1-4-quot-Flop py-Drive-Not-Reading/page9 So I tried to force formatting in DOS at 360k, and sure enough it worked! I can then read the diskette back, write on it, etc... And of course it failed formatting at 1.2 Mb. But the drive (Chinon FR-506) is a 1.2M one, and reads fine at 1.2M! Any clue? Is there a drive setting that would prevent it to write at high density but let it do at low density? Marc > Date: Tue, 18 Aug 2015 21:30:31 -0700 > From: cclist at sydex.com > To: cctalk at classiccmp.org > Subject: Re: 5.25 floppies that read but don't write > > On 08/18/2015 09:05 PM, Marc Verdiell wrote: > > > > > > I have connected a 1.2M 5.25" floppy to my computer. After a bit of > > jumper learning and setting, it's recognized and reads my old DD and > > HD floppies fine. But for the life of me I cannot write to it. Not > > under DOS, Win98, or WindowsXP. Which all read fine. > > Make sure that "WRITE GATE" goes low (use a logic probe) on pin 24 of > the drive while you do your write. If so, your floppy write circuitry > has a problem. I.e., it's not the cable. > > --Chuck >

10 years, 10 months

Power supply connector pin crimping, and 8-inch FDD power connectors (another chapter in the Quay 900 saga)

by spacewar＠gmail.com

Last week I wanted to test some half-height eight-inch double-sided drives (NEC, Mistubishi, and Qume) on the Quay 900. I cabled a Mitsubishi drive in place of the original CDC/MPI 9406 77618022 drives, and the machine apparently wouldn't reset properly, since I wasn't getting the prompt from my ROM monitor either on power-up or by manually resetting it. I poked around a bit and discovered that the +5V DC supply was at about 0.7V. I disconnected the Mitsubishi, and it still didn't work, and the +5V was still at 0.7V. Uh oh, what did I break? After a lot of pulling of hair, gnashing of teeth, and sacrificing a chicken at midnight, I discovered that +5V pin in the connector that plugs onto the switching power supply was not crimped properly. It was partially crimped, but the wire was just loose. The cable connector is an AMP (now TE) 87025-7 "Ampmodu" 0.156-inch pitch shell which accepts 102103-3 rectangular crimp receptacles. The shell has 20 positions, of which they inserted a keying plug in position 1, and only use contacts in some of the even positions from 2 though 20, because the header on the power supply PCB only has every other pin loaded. TE no longer makes the 87025-7, but they still make the 87025-8, which is apparently the same thing without the part number being stamped on the housing. I don't need another housing though, just a pin, because without the right extraction tool I hadn't been able to get the old pin out without mangling it a fair bit. Mouser and Digikey sell the pins in small quantity for $0.50 each, which seems absurdly high for a crimp pin with only tin plating. (There's another part number for a gold contact, but distributors don't stock it.) Just for the hell of it, I looked up the TE manual (hand) crimping tool designed for this pin, p/n 90274-2. It sells for over $6500. There is a used one on eBay for $75, but I've had bad experience buying used crimping tools. The only crimping tool I have on hand is designed for terminals with a round shell that just have to be crimped flat, vs. for terminals with V-shaped edges that have to be folded back in, as is typical of Molex pins and the like. I decided to order an inexpensive ratcheting crimping tool from an Amazon seller. It's an Iwiss SN-28B, also sold under the Estone and other brands. The Iwiss was $19. I couldn't tell from the photos whether it would be suitable. It turns out that it worked perfectly for the TE pins. It has two pairs of dies stacked with one pair having a larger profile, so it does crimp both the conductor and the insulator at the same time, which I wasn't expecting for a sub-$20 tool. That got the machine working again, and I verified that the CDC/MPI drives are still working, or at least working as well as they were before. I'm still seeing a lot of unreliability when using double-density on the highest-numbered tracks (closest to spindle). Could be the wrong amount of precomp, or the low-quality data separator design. Since one of the two MPI drives gets more errors than the other, there may be some issue with drive alignment or drive electronics adjustment as well. I unplugged the MPI drives and plugged in the Mitsubishi. Once again the machine wouldn't reset properly. It turns out that even though this bizarre variant of the 9406 uses the Shugart pinout for the data connector instead of the MPI pinout, and uses the same DC power connector as the Shugart, instead of the header used in normal MPI 9406 drives, the DC power connector pinout for the MPI does NOT match the Shugart DC pinout, as also used by the various half-height drives I want to try. I'm becoming less and less impressed with these MPI drives as I learn more about them. With the Mitsubishi cabled up to the Quay, but using a separate DC power supply with the correct pinout, I was able to verify that the Mitsubishi drive actually works fine. When used with the Quay FDC, it does need some retries for double-density on the inner tracks, like the MPIs, but it doesn't need as many retries as either of the MPI drives.

10 years, 10 months

Looking for RL8A controller card

by charlesmorris800＠centurytel.net

I have a PDP-8/A with a flaky RL8A (M8433) controller card. I can't track the fault down. I've spent enough hours on it by now that I'd just as soon buy another one. Anyone have one to sell? Or possibly could repair mine (for compensation)? thanks Charles

10 years, 10 months

OpenVMS TCP/IP Services 5.3 availability

by RichA＠LivingComputerMuseum.org

We are currently running TCP/IP Services 5.1 under OpenVMS 7.3 on the museum's VAX-11/780-5. The telnet listener has a known issue which is fixed in v5.3, but we have not been able to locate this (we've asked in the right places). Was this on a ConDist platter? Or was it made available in some other way? We have a perpetual license for VMS, and renew our other licenses annually, so PAKs are not an issue. Would someone be willing to loan us the install media? Or otherwise make this available? Thanks, Rich Rich Alderson Sr. Systems Engineer Living Computer Museum 2245 1st Ave S Seattle, WA 98134 Cell: (206) 465-2916 Desk: (206) 342-2239 http://www.LivingComputerMuseum.org/

10 years, 10 months

More on manuals plus rescue

by kevin_anderson_dbq＠yahoo.com

Wow, I have just looked at the manuals collection at the Internet Archive site. I honestly can say I don't like it, but I will say it is because this is not how my mind works in organizing stuff. I am immediately turned off by the tiling of 'cards" on the screen and the categorizing of collections. I know it more closely matches tablet apps and how they seemed to be designed, but I can also say, although I am the user of a tablet, I am not always happy with that approach. Even switching to the list view within IA didn't help much. I think it is great that Bitsavers material can be saved in more than one location, whether that be identical mirrors on multiple servers or with material copied into another environment. The point being the access to material and minimizing any risk of it all disappearing at once. But I agree that correct attribution of where material comes from is also very important. And multiple interfaces to how to search and find information can be fine to, as we all think differently. I just happen to prefer collapsible trees, textual lists, and drill-down methods more than I do other newer visual methods. My previous experience with Internet Archives has been mainly looking for old videos from the 1940s, 50s, and 60s through primarily the Prelinger archive, plus some texts and books that I found through Google and other search engines, and in using the Wayback machine. Seeing this new interface to the Internet Archives made it clear that I haven't checked IA since they apparently redid this interface, and all I can't say is I don't like it, and clearly if I can't find the item I need from IA through a Google search, then I won't be trying to find it directly from Internet Archives. The interface used at the Internet Archive is not Jason's fault. And certainly not so if the interface changed after Jason had already started his project. But I also feel that this collection at Internet Archive didn't necessarily help in useful ways to archive the older computer stuff, at least not that I can see from this initial review. Or if the collection is still good, the web interface is hindering a proper appreciation of that material and access to it. It also doesn't help that modern implementations of web content is all database driven (which the Internet Archive is one such site), which on the surface ought to be great, but in reality isn't when one no longer has as much control over the levels and depths of web pages in the same way as direct folders on a file server. The more flat and eclectic nature of today's web pages, with the expectation that one will "leap" all over the place within a largely flat structure, possibly employing filters to limit choices, is much less useful in this case for archiving and organizing the material in question than say hierarchical tree structures. At least in my opinion.... Kevin Anderson Dubuque, Iowa

10 years, 10 months

5.25" floppy disk storage.

by ard＠p850ug1.demon.co.uk

Something non-technical from me for a change. Most of you in the UK will have come across 'Really Useful Boxes' and probably use them for storing cables, screws, etc (I wish they made anti-static ones ;-)). Anyway what I hadn't realised until today is that the 3 litre size is just the right size for storing 5.25" floppy disks (in their cardboard covers), it will take about 80 of them with enough free space to extract them easily. Finding modern boxes for 5.25" disks is not that easy (I have not found the size for 8" disks though :-() Even better, at the moment, Rymans (at least round here) have them on sale at 4 for \pounds 10.00 (normally \pounds 3.99 each). -tony

10 years, 10 months

MAINDEX-11 CZKMA Diagnostic?

by ben＠bensinclair.com

I'm again trying to debug my PDP-11/23, and I believe I'm having trouble with my M8067-LB/MSV-11 memory. According to the manual, there is a diagnostic program called CZKMA (for my 18-bit system), but I can't seem to find it. I have all of the xxdp images from AK6DN, but this one doesn't appear to be on any of those. Some searching shows references to it and even a (poorly) scanned source listing, but does anyone know if I can get it on a TU58 image or another format? Thanks! -- Ben Sinclair ben at bensinclair.com

10 years, 10 months

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