test-drb November 2014

test-drb@ccmp.vtda.org

200 participants
279 discussions

by jnc＠mercury.lcs.mit.edu

> From: Glen Slick > So is the original poster (Michael) really looking for already > formatted RX01 floppies, or will blank 8-inch single sided floppies do > just as well? Generic _single-density_ floppies are what the RX01/2 needs. So AFAIK any pre-formatted single-density floppy will work in either one. AFAIK, originally, all SSSD floppies came already low-level formatted, but that may have changed later on. (I don't recall if DSSD floppies exist; if they did, the RX0x would probably just ignore the second side.) I'm not sure what you mean by 'blank' - did you mean 'no data/ file system', or 'not low-level formatted'? The thing is that neither RX0x can _low-level format_ floppies (i.e. write sector headers, etc). They _have_ to have pre-formatted floppies. I have this bit set that DEC did it that way with the RX01 since that was the (then minimally-used) IBM standard; if so, probably they just continued that way with the RX02. So you _can_ feed an RX0x xSDD floppies - if you first put them in a machine which will format them to xSSD low-level format. (Which I think someone has previously enquired about here.) Noel

10 years, 1 month

RX01 Floppies

by jnc＠mercury.lcs.mit.edu

> On 11/21/2014 2:26 PM, Glen Slick wrote: > Is it correct that RX01 format floppies can be created from blank > floppies with a standard PC floppy controller (or at least some > controllers / motherboards, depending on the controller chip) while > RX02 format floppies cannot? My understanding (perhaps incorrect, if so, someone please correct me) is that the wart-level-detail answer to this question is that '_blank_ RX02 floppies can be created on anything that can create RX01 floppies', but that RX02 floppies _with data on them_ can only be created on RX02 drives. I.e. an RX02 is fed RX01 floppies, which it then writes in the unique-to-DEC double density RX02 format. (As Chuck explained, the _headers_ are in the standard IBM form, but the _data_ part of the sectors is written in a DEC-specific double-density format.) Noel

10 years, 1 month

Re; What to look for in a Model 33 Teletype - a newb's buyer's guide?

by jnc＠mercury.lcs.mit.edu

> From: drlegendre > And one more - how do you differentiate a 20mA current-loop model from > a 'standard' RS-232 model? I believe the Model 37 is the RS-232 Teletype. (Is it based on the 33, or 35? I don't know.) If you have a working UNIBUS PDP-11, there are still 20mA serial interfaces avalable for it. I have a DL11-C (M7800-YA) you can have for what I paid for it (a song, just about), and someone on eBay has a DZ11-C (M7814) for sale for cheap; someone else there has the breakout panel for it. Noel

10 years, 1 month

What to look for in a Model 33 Teletype - a newb's buyer's guide?

by drlegendre＠gmail.com

I've gone off the Deep End and now I just have to re-have a Teletype model 33.. I feel awful about what became of the junker I bought for $15 when I was a 13 year-old and wish I still had it today, so I could fix it and put it to use. So what should a mentally-challenged guy like myself be looking for, in a Model 33 - preferably an ASR model with the paper tape reader? What does and doesn't go bad? Are there any serious game-changing, show-stopping or buzz-killing issues that effectively render one of these units as a parts donor? What differences exist between the various ASR-model units, as they progress through the years? What does one look for - and more importantly, what to avoid? And one more - how do you differentiate a 20mA current-loop model from a 'standard' RS-232 model? Can you tell from the rear panel, or do you need to go under the hood?

10 years, 1 month

What to look for in a Model 33 Teletype - a newb's buyer's guide?

by radiotest＠juno.com

At 02:58 PM 11/21/2014, drlegendre wrote: >I have virtually no idea what any of that means. =/ The 20 mA current interface was the standard current loop interface for Teletypes such as the ASR-33 sometimes used as consoles for DEC minis. I used them for a number of years on a couple of pdp8/m systems that had ASR-33s as consoles, and also took care of many 20 mA loops used with other Teletype models when I worked as an Associated Press technician in the early 1980s. AP used Lenkurt data sets to receive data from analog telco loops and convert it to current loops for teletypes. Dale H. Cook, GR / HP Collector, Roanoke/Lynchburg, VA http://plymouthcolony.net/starcity/radios/index.html

10 years, 1 month

RX01 Floppies

by jnc＠mercury.lcs.mit.edu

> From: tony duell >> the wart-level-detail answer to this question is that '_blank_ RX02 >> floppies can be created on anything that can create RX01 floppies' Sorry, I was slightly imprecise - I guess I should have said '_blank_ floppies that an RX02 can use to write double-density RX02 floppies can be created on anything that can create RX01 floppies'. But the bottom line is the one I gave: blank floppies which one can use in an RX02 can be created on anything that can make RX01 floppies. > An RX02 drive can reformat an RX01 disk as RX02. Right, that was what I meant with: > an RX02 is fed RX01 floppies, which it then writes in the unique-to-DEC > double density RX02 format If anyone wants to see the gory details, "RX02 Floppy Disk System User Guide" (EK-RX02-UG-001) has them on pg. 4-41, "4.3.3.5 Set Media Density (100)". Sections 1.5.2 ("Recording Scheme") and 1.5.3 ("Logical Format") give the technical details of the floppy content in quite complete form. Noel

10 years, 1 month

5.25" SCSI Drives

by alexmcwhirter＠mojovapes.net

Does anyone need any of these drives? I have 18 of them that I don't need and are just taking up room. Anyone who's willing to pay for shipping can have some or all of them. I can only power test them at the moment. Some are regular 8 bit SCSI 50 pin, and some are 16 bit wide SCSI 68 pin. Sent from my iPhone

10 years, 1 month

Re; What to look for in a Model 33 Teletype - a newb's buyer's guide?

by jnc＠mercury.lcs.mit.edu

> From: drlegendre > Though again, I don't know how or why that came into the conversation. You were asking about RS-232 for a Teletype; I was thinking, bring the mountain to Mohammed (a 20mA interface on the computer), not the other way around. Noel

10 years, 1 month

Who's rewired their house for this hobby?

by jnc＠mercury.lcs.mit.edu

> From: Todd Killingsworth > I realized that old machines took lots of power. But do the collectors > here wire up their homes and keep machines there? Heh, about to join this crew! I'm having the electricians in to put in a whole separate subsidiary panel (the existing ones are all pretty full), and run outlets from that (with those Hubble locking 3-pin sockets). > my wife thinks I'm completely certifiable. That's not the important question, which is 'is she tolerant of your insanity'? :-) > Todd Goodman > My wife thinks I'm certifiable as well since there couldn't possibly be > anyone else in the world interested in this "junk." So subscribe her to CCTalk... :-) > Oh, and also that I'm a "semi-hoarder." Duhhh! > From: Chuck Guzis > Where you get into the exotica is 3-phase service. There, you need a > cooperating utility and a deep pocketbook. Be prepared to be turned > down flat by your utility with the excuse that "We don't distribute 3 > phase in your area". Or they will try and give you what my house has (it came that way, the previous owner was a serious woodworking guy), which is 400A 3-phase service - but it's not really 3 phase. The area has two-phase service, and they hung a small transformer on the pole outside my house and wired it up to produce 3 phases that _will_ run a three-phase motor - but the third phase is like 170V to neutral, not 120V. (I forget the details, a foreman explained it to me once, but I've since forgotten.) So things that try and take three phases and power a bunch of 120V things, with some on each phase, won't work. Noel

10 years, 1 month

Re; What to look for in a Model 33 Teletype - a newb's buyer's guide?

by jnc＠mercury.lcs.mit.edu

> From: drlegendre > I have virtually no idea what any of that means. Clearly because you don't have a UNIBUS PDP-11! :-) Oh well, it was worth a shot (I didn't know). Noel

10 years, 1 month

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test-drb November 2014