Anyone Have a Working AlphaStation 200 to Run Some Tests For Me?
I can’t remember if I already asked, but I need to find a working example and ask it’s owner to run some tests on it for me to help me diagnose a fault on mine. Ideally the machine would be running VMS. Thanks Rob Sent from my Windows 10 phone
Pascal/8002 or other compilers for Tek 8002 dev. system?
Does anyone have information about (or a copy of) the Pascal Development Co. Pascal/8002 Universal Program Development Package, that ran on the Tektronix 8002 development system? The only thing I've found is a blurb in Computerworld 1979-08-13 p. 56. Alternatively, I'm very interested in any other compiler that ran on the 8002 and produced p-code or bytecode, or any such compiler running on ANY machine which Tektronix may have used for product development. They might well have done cross-development from a mini or mainframe, but I'm guessing that they probably used their own 8002 system. Context: the Tektronix DAS 9100 logic analyzer is Z80 based, and contains many ROMs, mostly 8KB MK36000 series masked ROMs and MCM68764 EPROMs, but only one ROM appears to contain much actual Z80 code. That 8K ROM is labeled "INTERP" and contains a bytecode interpreter. Apparently all the other ROMs are full of bytecode. The bytecode does not match the UCSD p-code nor the ETHZ P4 p-code. I've started disassembling it, but haven't yet learned too much.
FW: Non-DEC keyboard lookalikes (was: VT1xx stuff)
Oops, I forgot the list doesn't allow attachments! http://www.binarydinosaurs.co.uk/nonDECkeyboards.jpg A -- Adrian/Witchy Binary Dinosaurs creator/curator Www.binarydinosaurs.co.uk - the UK's biggest private home computer collection? -- Forwarded Message From: Adrian Graham Date: Tue, 10 May 2016 20:48:57 +0100 To: "Discussion: On-Topic and Off-Topic Posts" Conversation: Non-DEC keyboard lookalikes (was: VT1xx stuff) Subject: Non-DEC keyboard lookalikes (was: VT1xx stuff) Since I now have a couple of these and google is coming up blank-ish has anyone come across a VT keyboard, possibly from a Plessey PT100 style terminal, that is 99% VT100 in shape, colour and key layout? Even the 6mm jack plug though I know Apple used that too on the Lisa. I found a message thread from here in 2002 about the VT131 and what sounds like an identical keyboard but aside from 'don't knows' and a mention of Plessey nothing else was found and it descended into chat about scanning Microfiche. I toyed briefly with the thought that I'd ended up with the VT and keyboard of those messages but the OP of that was in Champagne IL. Earlier tonight I dismantled one of them in the hope of seeing a manufacturer or any sort of branding but nada. There's a 2716 EPROM marked 'PKB00' which I dumped but there's nothing of note in there either. Maybe the pic will help, maybe not since you'll think 'that's a VT keyboard' :) -- Adrian/Witchy Binary Dinosaurs creator/curator Www.binarydinosaurs.co.uk - the UK's biggest private home computer collection? -- End of Forwarded Message
Re: "Retro Repair" key electronics skills?
On 05/10/2016 02:33 PM, Bill Sudbrink wrote: The other is that, as I said before, any ground connection has impedance (it's the inductance that is troublesome normally) so that points (say IC pins) that are shown as grounded may actually have a voltage difference between them. If I think about it too much, this gives me the willies, the same way. I have a 3500 Lb Sheldon lathe. During rebuilding of it, I got a very sensitive electronic level, to aid in making sure the bed was reground straight. I found that when I walked from one end of the lathe to the other, it tilted about one arc second. That was my weight deflecting the concrete floor of my basement, causing the lathe to tilt slightly. All structures, including the earth, deflect under load. Jon
Re: "Retro Repair" key electronics skills?
On Tue, 10 May 2016, dwight wrote: > In order to trouble shoot, one needs to know how it is suppose to work. > This often means studying schematics, data sheets and sometimes even > app-notes. Cool. I'm good on this. I love schematics when I can get them. I can't always figure out what I'm looking at but it sure helps vs looking at a board! > Avoid the replacing everything, until it starts working, type trouble > shooting. As well as being a waste of time, it is more likely that you > will introduce new problems in the process. Don't replace a part unless > you can prove it to yourself that it is the most likely source of the > error. This strikes me as very good advice. I use the same type of mentality when I troubleshoot computer components and servers. I'm sure it's just as sound when dealing with components. > This usually means running experiments. Since you are a coder, I > find that anything with a working processor can be used as a self > debugging tool. I love that phrase "Self debugging tool." > EPROMs or front panels are great for trouble shooting. Simple test are > best. I'm a Unix guy. Simple is almost always better. :-) > Many fear power supplies. Linears are the easiest because they are > always some form of feedback loop. You just follow the loop until you > find two points that are opposite directions from where the input point > predicts the output point should be( goes back to knowing how it should > work). Okay, I'm one of those with a little fear of power supplies. It's little because I'm still ignorant (*grin*). Funny you should mention power, I'm studying this section on DC metering to build up to learning more about power circuits: http://www.allaboutcircuits.com/textbook/direct-current/chpt-8/what-is-a-meter/ BTW, I'm growing pretty fond of this instruction on allaboutcircuits. They have some really great material with excellent explanations & drawings. > If you can't find a schematic on the web, draw one. As a minimum, > have a block diagram. I keep reading that. I'm taking it to heart, mainly because I can barely keep up with one part of a circuit before having to move on and figure out a different part. Writing it down is the only way I could do it anyway. :) > I'm sure you have heard of the "scientific method". Trouble shooting is > just that. It is the repetitive process of making an educated guess as > to the source of the problem and then having an experiment to prove it > either true or false. Try to have experiments that are conclusive. That's good advice, in general, I think. I try to do the same with any type of troubleshooting. Even the Monte Carlo method (which I think rocks) is usually framed as an controlled experiment. > Learn to use a two channel oscilloscope with trigger and delayed sweep. Great! I've been looking into that. I'm guessing that helps when you are trying to look at a detailed edge/level and you can overlay the two wave forms? Also do you use variable holdoff much in real life? I'm reading about how it works, and it sounds useful in theory (and if I buy a scope, it *sounds* good). However, at my level, I'm not sure I'd ever use it. It just keeps coming up a lot when reading about scopes. -Swift
Re: "Retro Repair" key electronics skills?
In order to trouble shoot, one needs to know how it is suppose to work. This often means studying schematics, data sheets and sometimes even app-notes. Avoid the replacing everything, until it starts working, type trouble shooting. As well as being a waste of time, it is more likely that you will introduce new problems in the process. Don't replace a part unless you can prove it to yourself that it is the most likely source of the error. This usually means running experiments. Since you are a coder, I find that anything with a working processor can be used as a self debugging tool. EPROMs or front panels are great for trouble shooting. Simple test are best. Many fear power supplies. Linears are the easiest because they are always some form of feedback loop. You just follow the loop until you find two points that are opposite directions from where the input point predicts the output point should be( goes back to knowing how it should work). If you can't find a schematic on the web, draw one. As a minimum, have a block diagram. I'm sure you have heard of the "scientific method". Trouble shooting is just that. It is the repetitive process of making an educated guess as to the source of the problem and then having an experiment to prove it either true or false. Try to have experiments that are conclusive. This is why I don't much care for the piggy back RAM test. It may or may not tell you that there is a problem with the RAM that you are checking. Learn to use a two channel oscilloscope with trigger and delayed sweep. Dwight From: cctalk on behalf of Swift Griggs Sent: Tuesday, May 10, 2016 1:03:44 PM To: General Discussion: On-Topic and Off-Topic Posts Subject: RE: "Retro Repair" key electronics skills? On Tue, 10 May 2016, tony duell wrote: > It's a very real problem, it's the main reason for decoupling capacitors > which provide a local source of power with a low impedance connection > (as they are so close to the IC). It seems like there is a lot of "fiddling" with those types issues and getting good at doing so is part of the process of getting profecient with component level troubleshooting. That's why working with electronics "kits" (ie.. kit based projects) is about my speed right now. In most of those cases, folks have worked out the kinks involving connection issues, but I'm still just doing analog stuff. I have no idea how much it'll matter when I go to learn a bit about digital. However, that quote about digital circuits being made from analog physical bits seems like good foreshadowing. So, we'll see. I'm still playing along with projects from a kids' Elenco kit. I'm having fun with timers and making "bleeps and bloops". I'm also using it to try and figure out how about 5% of my borrowed ocilliscope works. I've got the manual, it's just figuring out what everything means is a bit challenging right now. So, it helps teach me how to calibrate the darn thing to just sit on something that looks like a sine wave etc... -Swift
News about hpmuseum.net
The following was posted on hpmuseum.org this morning: *RE: Jon Johnston Passes * As an update to the sad news of Jon Johnston's death, I can advise that the HP museum and the hpmuseum.net website he built will be continued and maintained for the foreseeable future. Over the last 8 months I have worked with Jon in restoring items from his collection of equipment and, among a range of items, recently restored an HP2116A computer to working order - one of only two Jon was aware of in the world and the only one that's operational. At this stage we have not been able to access the website and put any notices or updates but that should be addressed shortly. Jon's wife has asked me to look after the museum and website for the foreseeable future and as much as possible, continue to develop the museum in line with Jon's vision and objectives. As a short background, I joined HP Australia in 1982 as a Customer Engineer maintaining HP3000s, HP250s, all peripherals, terminals etc. I stayed with HP for over 26 years (including 5 years in Palo Alto) in a range of Services roles and have many fond memories of the company and the people I worked with. While my ability to invest time into the museum is more limited than Jon's, I hope to honour both his memory and the legacy of the 'old HP' by keeping the museum going as best I can, hopefully with help from the HP interest groups across the world. David Collins
Non-DEC keyboard lookalikes (was: VT1xx stuff)
Since I now have a couple of these and google is coming up blank-ish has anyone come across a VT keyboard, possibly from a Plessey PT100 style terminal, that is 99% VT100 in shape, colour and key layout? Even the 6mm jack plug though I know Apple used that too on the Lisa. I found a message thread from here in 2002 about the VT131 and what sounds like an identical keyboard but aside from 'don't knows' and a mention of Plessey nothing else was found and it descended into chat about scanning Microfiche. I toyed briefly with the thought that I'd ended up with the VT and keyboard of those messages but the OP of that was in Champagne IL. Earlier tonight I dismantled one of them in the hope of seeing a manufacturer or any sort of branding but nada. There's a 2716 EPROM marked 'PKB00' which I dumped but there's nothing of note in there either. Maybe the pic will help, maybe not since you'll think 'that's a VT keyboard' :) -- Adrian/Witchy Binary Dinosaurs creator/curator Www.binarydinosaurs.co.uk - the UK's biggest private home computer collection?
Re: VT1x1 keyboard (was Re: VT101 screen adjustment)
On Tue, May 10, 2016 at 3:26 PM, Adrian Graham wrote: > ... I had the VT131 one in bits on Sunday to fix the power switch which > had disintegrated in the same way my VT102 did. Yeah... I had that exact problem last year with a VT100. I'd say that of several DEC terminals I've repaired, the two most common things were the EIA receivers (static/lightning, most likely) and the power switch. Distant third is video problems. -ethan
RE: "Retro Repair" key electronics skills?
On Tue, 10 May 2016, tony duell wrote: > It's a very real problem, it's the main reason for decoupling capacitors > which provide a local source of power with a low impedance connection > (as they are so close to the IC). It seems like there is a lot of "fiddling" with those types issues and getting good at doing so is part of the process of getting profecient with component level troubleshooting. That's why working with electronics "kits" (ie.. kit based projects) is about my speed right now. In most of those cases, folks have worked out the kinks involving connection issues, but I'm still just doing analog stuff. I have no idea how much it'll matter when I go to learn a bit about digital. However, that quote about digital circuits being made from analog physical bits seems like good foreshadowing. So, we'll see. I'm still playing along with projects from a kids' Elenco kit. I'm having fun with timers and making "bleeps and bloops". I'm also using it to try and figure out how about 5% of my borrowed ocilliscope works. I've got the manual, it's just figuring out what everything means is a bit challenging right now. So, it helps teach me how to calibrate the darn thing to just sit on something that looks like a sine wave etc... -Swift
RE: "Retro Repair" key electronics skills?
> > My father is a civil engineer. When I was a little > kid, he was in the US Air Force. We would frequently > go to the runway snack bar, get ice cream and watch > the B-52s do "touch-and-go" landing practice. The > plane's wings would "flap". It raised the hair on > the back of my neck. My dad explained that, if they > didn't flex, the wings would break off. After a > while, I understood, intellectually. It still "gave > me the willies". Later I had a similar experience > when I was with him in a tall building and realized > that it was "waving in the wind". Same thing, if it > didn't flex, it would fall. That reminds me of the following joke : There is an airline passenger. During some particularly turbulent conditions he looks out the window and sees the plane's wings flexing. He looks very worried. The flight attendant comes over to him and tries to comfort him by saying 'Our pilots are fully trained to fly in conditions like this. It's only turbulence, it's quite normal' He replies 'You don't undertand. I work for Boeing. I am one of the men who designed this aircraft. The wings are not supposed to flex like that.' > > The other is that, as I said before, any ground > > connection has impedance (it's the inductance that > > is troublesome normally) so that points (say IC pins) > > that are shown as grounded may actually have a > > voltage difference between them. > > If I think about it too much, this gives me the > willies, the same way. It's a very real problem, it's the main reason for decoupling capacitors which provide a local source of power with a low impedance connection (as they are so close to the IC). That's why I said that most times the interconnections are the hard part of a digital circuit. -tony
RE: "Retro Repair" key electronics skills?
tony duell wrote: > Another of Don Vonada's laws is 'There is no such > thing as ground'. My father is a civil engineer. When I was a little kid, he was in the US Air Force. We would frequently go to the runway snack bar, get ice cream and watch the B-52s do "touch-and-go" landing practice. The plane's wings would "flap". It raised the hair on the back of my neck. My dad explained that, if they didn't flex, the wings would break off. After a while, I understood, intellectually. It still "gave me the willies". Later I had a similar experience when I was with him in a tall building and realized that it was "waving in the wind". Same thing, if it didn't flex, it would fall. > The other is that, as I said before, any ground > connection has impedance (it's the inductance that > is troublesome normally) so that points (say IC pins) > that are shown as grounded may actually have a > voltage difference between them. If I think about it too much, this gives me the willies, the same way. Bill S.
VT1x1 keyboard (was Re: VT101 screen adjustment)
On 10/05/2016 16:14, "tony duell" wrote: > The keyboard itself is the same on the VT100, VT101, VT102, etc. The interface > circuit on the main logic board is much the same too, so the info in the > technical manual is of relevance. I'm reading that in moments of quietness since the VT101 is showing random key decoding no matter which keyboard is plugged in. It only does it during keypresses so it doesn't seem to be a random bit setting itself. If I press and hold for example 's' I'll get several 's' on screen then something else will happen, then more 's'. +5V on the board is at +4.96V and the VT POSTs correctly so it's not an obvious RAM glitch, and it doesn't seem to be a warmup problem either. > If you can stick one of my hand-drawn diagrams, I have reverse-enegineered > the VT101 logic board and PSU board. Keyboard and video you can get from > the VT100 printset, and I couldn't find a mains input bracket to trace out > (maybe > sometime) but that is pretty simple anyway. If you want the VT101 board > diagrams just ask me nicely. I always ask nicely don't I? :) Drawings would be excellent please, and in return I can send pics of any internals you need including a mains input bracket. I had the VT131 one in bits on Sunday to fix the power switch which had disintegrated in the same way my VT102 did. Cheers -- Adrian/Witchy Binary Dinosaurs creator/curator Www.binarydinosaurs.co.uk - the UK's biggest private home computer collection?
RE: VT101 screen adjustment
[Your VT101 video board] > > It's the same board as the VT102, just checked. I can easily check the caps. >From what I remember there are at least 3 different video boards found in VT1xx's and any could appear in any model terminal. -tony
Re: VT101 screen adjustment
On 10/05/2016 16:10, "tony duell" wrote: > [VT101 with vertical linearity problems] > >> Yes indeed. Fortunately this one wielded under my trimmer and all is >> properly aligned now. All I need to do now is troubleshoot the keyboard >> circuit which I hope is the same as the VT102... > > In general it is a bad idea to cure faults by adjustments. Unless somebody > has been twiddling, these adjustments only drift if some other component is > failing. They are there to initially set the circuit up for the components > that > are used, or in some cases, particularly in delta-gun colour CRTs, to correct > for external conditions, such as magnetic fields. > > My guess is a capacitor is failing. So far you are still within the range of > the > adjusment, but it may well get worse. I don't know which video board you > have (there are at least 3 different ones), but if it's the one on pages 54-58 > of the VT100 printset on bitsavers (the VT100 and VT101 use the same > video board), then check C318 and C319 for a start. It's the same board as the VT102, just checked. I can easily check the caps. Cheers, -- Adrian/Witchy Binary Dinosaurs creator/curator Www.binarydinosaurs.co.uk - the UK's biggest private home computer collection?
PDP-8 core memory board
FAYI: http://www.ebay.com/itm/262419353233 DEC H219a & G649 8K X 12 Core Memory Stack Noel
RE: "Retro Repair" key electronics skills?
> > Remember one of Don Vonada's laws 'Digital Circuits are made from > > Analogue Parts' > > That's an interesting saying. Maurice Wilkes (as in EDSAC) once told me 'A digital circuit is like a tame animal. An analogue circuit is like a wild animal. Every so often the digital circuit decides to go back to the wild' :-) Another of Don Vonada's laws is 'There is no such thing as ground'. This has 2 meanings. The first is the obvious one that a voltmeter has 2 leads and it is up to you to choose a reference point to measure voltages with respect to, The other is that, as I said before, any ground connection has impedance (it's the inductance that is troublesome normally) so that points (say IC pins) that are shown as grounded may actually have a voltage difference between them. -tony
RE: "Retro Repair" key electronics skills?
On Tue, 10 May 2016, tony duell wrote: > Remember one of Don Vonada's laws 'Digital Circuits are made from > Analogue Parts' That's an interesting saying. > So what appears to be a solid power or ground connection may have > different voltages along it. Those types of nuances and inconsistances are always frustrating but I understand it's the nature of working in the real world, rather than software. :-) > Getting back to the original request, my main worry is the 80 hour time > limit. Oh, that's just about the amount of time it takes before I rotate to the next hobby for a while. However, I find that the better I get a things, the more I enjoy them and then the rotations get longer for those hobbies. I just know that eighty hours is about as much as I can spend just doing pure learning before my mind needs a break for a while. It's not really a "limit". It's more my "bite size". > I am far from being the most knowledgeable person here, and perhaps I am > a very slow learner, but I must have spent over 80 _thousand_ hours > learning electronics and related subjeccts. And FWIW I am still > learning. I hear ya. There is nearly infinite depth there, no doubt. I just want to build up to a basic skill level that gets me functional in a few areas I care about. -Swift
RE: VT101 screen adjustment
> Yes indeed. Fortunately this one wielded under my trimmer and all is > properly aligned now. All I need to do now is troubleshoot the keyboard > circuit which I hope is the same as the VT102... Forgot to mention... The keyboard itself is the same on the VT100, VT101, VT102, etc. The interface circuit on the main logic board is much the same too, so the info in the technical manual is of relevance. If you can stick one of my hand-drawn diagrams, I have reverse-enegineered the VT101 logic board and PSU board. Keyboard and video you can get from the VT100 printset, and I couldn't find a mains input bracket to trace out (maybe sometime) but that is pretty simple anyway. If you want the VT101 board diagrams just ask me nicely. -tony
RE: VT101 screen adjustment
[VT101 with vertical linearity problems] > Yes indeed. Fortunately this one wielded under my trimmer and all is > properly aligned now. All I need to do now is troubleshoot the keyboard > circuit which I hope is the same as the VT102... In general it is a bad idea to cure faults by adjustments. Unless somebody has been twiddling, these adjustments only drift if some other component is failing. They are there to initially set the circuit up for the components that are used, or in some cases, particularly in delta-gun colour CRTs, to correct for external conditions, such as magnetic fields. My guess is a capacitor is failing. So far you are still within the range of the adjusment, but it may well get worse. I don't know which video board you have (there are at least 3 different ones), but if it's the one on pages 54-58 of the VT100 printset on bitsavers (the VT100 and VT101 use the same video board), then check C318 and C319 for a start. -tony
RE: VT101 screen adjustment
> > Another good practice is to use several carbon-composition resistors in > > seri$ > > Actually, that makes me curious. Would a piece of pencil "lead" be a > workable substitute? I could imagine taking a drafting/art pencil lead > (the kind that's some 2-3 mm thick) with clip-leads, one on each end. > (Preferably inside some kind of container, so the connection on the HV > end is not exposed.) > > But I don't know whether its resistance would be too high (or too low, > though that seems unlikely) Actually pencil lead is suprisingly low resistance. Try sharpening a pencil at both ends and measuring it. When I was younger, I carefully cut and split a pencil apart lengthways. This left me with the lead in a trough of wood. A wire wrapped firmly round one end and a wire wrapped round that I could slide along made a reasonable varialble resistor. I can remember using it with a battery (probably about 4.5V to 6V) and a torch (flashlight) bulb as a dimmer, so the resistance can't be that high. The resistance does depend on the grade of pencil. The more 'black' it is. the lower the resistance. So a 6B has low restance, a 6H high, Of course we are all talking about rods of graphite, not the metal lead, right? -tony
RE: "Retro Repair" key electronics skills?
> > - Since I'm a coder, I understand boolean logic (which I hope would > > help with ICs). > > While it's an understandable point of view, especially for a coder, not > all ICs are digital logic - and even for those that are, understanding > non-digital-logic aspects of them can be useful. (I built an EPROM Remember one of Don Vonada's laws 'Digital Circuits are made from Analogue Parts' In my experience the most complex part of classic digital design (that is interconnecting physical componets, which may or may not be ICs) is the wiring. For anything of moderate speed you have to design the interconnections as transmission lines, know how to terminate them and the like. You have to understand that no connection has 0 impedance (0 resistance I can accept, but not 0 inductance or 0 capacitance to other connections). So what appears to be a solid power or ground connection may have different voltages along it. Getting back to the original request, my main worry is the 80 hour time limit. I am far from being the most knowledgeable person here, and perhaps I am a very slow learner, but I must have spent over 80 _thousand_ hours learning electronics and related subjeccts. And FWIW I am still learning. -tony
Re: "Retro Repair" key electronics skills?
On Tue, 10 May 2016, Mouse wrote: > While it's an understandable point of view, especially for a coder, not > all ICs are digital logic - and even for those that are, understanding > non-digital-logic aspects of them can be useful. Right now I've started looking at the textbooks & lessons here: http://www.allaboutcircuits.com/textbook/ Volume IV is about digital. However, I'm finding quite a few topics in the previous books are things I'm not strong in, either. I get the feeling one needs to have quite mastered analog before moving to digital. So, I completely believe you. > (I built an EPROM reader out of SSI TTL, and found it always read the > last octet as FF even in cases where I knew better. Once I brush up on theory a bit, I'll have to find me a project like that. -Swift
Re: "Retro Repair" key electronics skills?
> - Since I'm a coder, I understand boolean logic (which I hope would > help with ICs). While it's an understandable point of view, especially for a coder, not all ICs are digital logic - and even for those that are, understanding non-digital-logic aspects of them can be useful. (I built an EPROM reader out of SSI TTL, and found it always read the last octet as FF even in cases where I knew better. Turned out I forgot to connect the ground pin on the EPROM to circuit power ground; provided at least one input was low, it powered the chip through the input protection diodes, but when all connected pins were high - and all the non-address inputs that weren't high were tied to the ground pin - then all outputs perforce were too. But that failure mode would have been inexplicable if my mental model of the thing had been an ideal logic device.) /~\ The ASCII Mouse \ / Ribbon Campaign X Against HTMLmo...@rodents-montreal.org / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B
Re: VT101 screen adjustment
> Another good practice is to use several carbon-composition resistors in seri$ Actually, that makes me curious. Would a piece of pencil "lead" be a workable substitute? I could imagine taking a drafting/art pencil lead (the kind that's some 2-3 mm thick) with clip-leads, one on each end. (Preferably inside some kind of container, so the connection on the HV end is not exposed.) But I don't know whether its resistance would be too high (or too low, though that seems unlikely) /~\ The ASCII Mouse \ / Ribbon Campaign X Against HTMLmo...@rodents-montreal.org / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B
Re: Memodyne M80 Digital Cassette Recorder
On May 10, 2016, at 1:12 AM, jwsmobile wrote: > IIRc there was a Silent 700 that had cassettes? Or was it the KSR version > of the 800 dot matrix TI printers? I actually got to use one of these or one similar for a while: http://terminals.classiccmp.org/wiki/index.php/TI_Silent_700_Model_733 Back in high school, while working at University of Texas Center for Space Research. We had a line from the NASA laser-ranging network which ran into the TI which recorded anything incoming onto its cassette. I’d come in in the morning, switch the TI connection to an RS-232 into the PDP-11, and play back the tape onto the “gargantuan” hard drive, then change to a new tape and archive (put into a box) the old one. The PDP-11 would later send a week or more worth of observations to the campus CYBER to determine the orbit of whatever satellite was being tracked (usually LAGEOS, also Starlette and BE-2 (sic?).) The setup got replaced eventually by a CP/M system with 2 8” floppies (Balcones Computer Corporation, according to the box. I have never seen another one of those….). Accustomed as I was to the 5.25” floppies on my TRS-80, I walked into the lab the day after the new CP/M box was installed - and my jaw fell open. The 8” drives just kept running! No spin-down when not being accessed! Luckily someone was there to explain that that was actually by design, I didn’t need to shut down the box to keep from wearing out the disks. Fun times.
