test-drb December 2015

test-drb@ccmp.vtda.org

191 participants
268 discussions

double density floppy cable adapter for Intel Series II or III MDS

by spacewar＠gmail.com

Last month I made a trivial little cable adapter PCB to use with the Intel SBC 202 double-density M2FM floppy controller in an Intel Series II or III MDS (normally part of an MDS 720 subsystem). The usual SBC 202 cabling has two DC37S connectors on the MDS back panel, one for drives 0 and 1, and the other for drives 2 and 3. (There's a variant that has a ribbon cable to the internal drive as 0, and only one DC37S for drives 2 and 3.) Photos: https://www.flickr.com/photos/22368471 at N04/albums/72157659736489274 Schematic and board layout in Eagle and PDF: http://www.brouhaha.com/~eric/retrocomputing/intel/mds/mds-fd-adapter/ The adapter has no active electronics; it just wires a DC37P to a 50-pin header for a cable to one or two normal 8-inch floppies. I just got around to testing it yesterday, and was pleasantly surprised that my SBC 202 and the adapter worked on the first attempt. The SBC 202 was of unknown provenance so I didn't actually have much expectation of it working. I haven't yet tried more than one drive on it. Intel used radial ready signals from the drives, so the drive(s) have to be configured slightly differently than the factory defaults to be fully compatible with the MDS 720. I have one spare bare adapter PCB which can be made available for $5.95 plus shipping from Colorado if anyone else needs such a thing. I am NOT willing to source the connectors or assemble the boards. You can also order them in increments of three pieces directly from OSH Park: https://oshpark.com/shared_projects/AO0DZTr1 If there's demand for a few units, I can have a small run made in China very inexpensively, probably under $4 each plus shipping from Colorado. Richard Main has made fancier adapter PCBs that also support 34-pin cabling for the use of high-density 5.25 or 3.5 inch disks.

8 years, 4 months

Memory Voltage on MicroVAX II

by robert.jarratt＠ntlworld.com

I finally fixed my H7864 PSU so I can now run my rtVAX 1000. However, I think the machine is damaging memory boards. I checked the ripple and 5V looks OK, but 12V looks suspicious. Is the 12V supply used by the memory? Incidentally, as I have mentioned before, I have drawn out the schematics for the H7864 PSU. The schematics are drawn illogically, with mistakes almost certainly still there, but the Primary side I think is more reasonable now. Is there a good place to post these? Regards Rob

8 years, 4 months

TU-58

by anders＠abc80.net

> Date: Wed, 2 Dec 2015 12:40:08 +0000 > From: Rod Smallwood <rodsmallwood52 at btinternet.com> > To: "General Discussion: On-Topic and Off-Topic Posts" > <cctalk at classiccmp.org> > Subject: TU-58 > Message-ID: <565EE6A8.2030004 at btinternet.com> > Content-Type: text/plain; charset=utf-8; format=flowed > > Dear List > While the silk screeners process the panels I have a > couple of days for a little project > I have a TU-58 and yes it had gooey drive wheels. > Now it no longer has that problem but I have black and gooey fingers.!!! > > I know this issue has been addressed before. > So I think somebody must know where I can get the right tubing to > replace the degraded stuff. > The drive hub is 0.42" and the rubber bit was 0.62" o/d > A UK source would be nice, > > Rod > I'm also intessted in this. I have a dual TU-58 that belongs to my VAX 11/730 that need new capstan rubber. European source... /Anders

8 years, 4 months

I need to bring up a 11/20 shall I use a variac!?

by COURYHOUSE＠aol.com

I need to bring up a 11/20 shall I use a variac!? added core.... where can I find if I decide to add to it? ed sharpe _www.smecc.org_ (http://www.smecc.org/) (resent with address corrections)

8 years, 4 months

I need to bring up a 11/20 shall I use a variac!?

by COURYHOUSE＠aol.com

I need to bring up a 11/20 shall I use a variac!? added core.... where can I find if I decide to add to it? ed sharpe _www.smecc.org_ (http://www.smecc.org)

8 years, 4 months

PDP 11/15 or 11/20 frame powersupply and backplane

by jws＠jwsss.com

I'm looking for any of these, starting with most essentially the backplane. power supply next, then frame if anyone has one that is empty looking for some filling. Thanks Jim

8 years, 4 months

Announcing CBM15 V012 (new Beta release)

by drlegendre＠gmail.com

CBM15 V012 has been released to CSDB, and is currently available for download. http://csdb.dk/release/?id=143468 CBM15 is a telecommunications software, that facilitates direct two-way communications between a Commodore 64 computer and a Teletype Corp. M15KSR (or any other compatible machine). Note that CBM15 follows the 5/N/2 serial protocol, at a fixed line speed of 45.45 baud (22mS signalling period). As with any of these PC-to-TTY setups, an external RS-232 to Current Loop converter is required. This is an initial release, and upcoming releases will add new features and correct a bug or two. So.. am I the only one on the list(s) with a C-64 and an M15 on hand? If you have the required hardware, please give it a try - so far, I've had no feedback from any other 'real' M15 owner.. Thanks!

8 years, 4 months

DEC DD11B

by wdonzelli＠gmail.com

What is a DD11B backplane for? -- Will

8 years, 4 months

PDP-12 Restoration at the RICM

by michael.99.thompson＠gmail.com

I used my PDP-8/e at home to test the RX8E controller and the RX01 floppies that came with the PDP-12. Both worked OK. We found a bad SP380 on a M7102 board in the DW8E the Omnibus expansion chassis. This would not let the SKIP instructions work with the RX8E, RK05, or PC8E. Once we replaced the SP380 we were able to boot OS/8 from an RX01 floppy. This may be the only PDP-12 to ever do that. -- Michael Thompson

8 years, 4 months

[multicians] Emacs humor

by jws＠jwsss.com

This is a funny cartoon and subsequent discussion thread from the Multics discussion group about emacs. Names and personal info edited out due to archival by unknown parties of the list and that these folks might not want names and certainly not email addresses archived. Mentioning that not as a criticism, just to explain the format. I also edited the thread back to bottom posting. Original XKCD cartoon link. https://xkcd.com/378/ >> From: Multicians <snip> >> Subject: Re: [multicians] Emacs humor >> >>> >>> >>> Thanks, Gary. As an emacs diehart, I fully appreciate that. In fact, there is a silly phrase that many emacs users use, when referring to all the obscure key bindings that you get by default with emacs, or can create. It.s called: >>> >>> Control-Meta-Shift-Cokebottle >>> >>> I believe the history (someone can correct me if I.m wrong) is that Emacs was developed at the MIT AI Lab (by Richard Stallman) and initially written in Teco. It was developed on Lisp machines, which sported lots of modification keys on its keyboard. These included Control, Shift, Hyper, Meta, Super (and perhaps more). Naturally, emacs took advantage of some of these . at least those that were available on multiple terminals or could be emulated on lesser terminals. I remember when I worked at MIT LCS (down the hall from MIT AI), we had a key binding on our Lisp Machines that called the elevator to the 8th floor. I don.t remember the key binding, but I.m sure it used a few of these modification keys (and probably .e. for .elevator. as the modified key). In any case, the class of these funky key bindings was referred to as Control-Meta-Shift-Cokebottle. >>> >>> I.m sure I.ve gotten some of the facts wrong, but I.m also sure that at least someone on this list will correct me! >>> >>> . Eric >> > > >> On Dec 1, 2015, at 11:30 AM, Ken <snip>> wrote: >> >> >> I seem to recall that one of the Lisp machine keyboard modifiers was "Top", and that the phrase was therefore >> >>> Control-Shift-Meta-Top-Cokebottle >>> >> Where, of course, you were typing the "Cokebottle" key with the Control, Shift, Meta, and Top modifier keys depressed. >> >> I think the elevator hack involved the AI Lab PDP-6 (or maybe, later, PDP-10), but I wouldn't be surprised if it migrated to the Lisp machines, too The old -6, especially, had added hardware to enable it to control the various robot devices the AI lab played with. Some AI Lab hardware guys gained access to the machinery room on the 10th floor and added some extra relay circuitry to one of the elevator controllers, and it wasn't much of a stretch to run the control wires down to the 9th floor machine room. IIRC it took a few years for whatever company was responsible for maintaining the elevators to discover the unauthorized modification and remove it. >> >> How long it stayed removed is an entirely different question, of course. >> >> Ken >> MIT-LCS '72-'80 >> Multics ARPANET software >> On 12/1/2015 11:42 AM, Eric <snip> [multicians] wrote: > > > I just knew I had that facts wrong! Yes, you.re right. I remember the Top key now. > > I do know that the elevator hack worked on Lisp machines, but I think you.re right that it also worked on some other interfaces. I remember getting frustrated when I.d be .ready to leave. (at 2am, or so), and would call the elevator, and then I.d have to fix .one more bug., and by the time I got to the elevator, I actually had to push the boring old button to get the elevator doors to open! :-) > > . Eric

8 years, 4 months

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test-drb December 2015