On 17/06/14 08:30, upsidedown@downunder.com wrote:> On Mon, 16 Jun 2014 10:41:59 +0100, Tom Gardner > <spamjunk@blueyonder.co.uk> wrote: > >> On 16/06/14 08:13, Don Y wrote: >>> I think when driving with a motor, you have more control over >>> whether or not the tape ever "backs up". Relying on the sprocket >>> holes to control the motor (speed) would be problematic as there >>> is no guarantee that the tape won't buckle, fold, fall out of the >>> slot, etc. so you've already got to have some local feedback on the >>> motor/drive. >> >> I'm not sure what you mean by that. The 1000cps readers that >> spat the tape 6' across a room into a hopper: > > I have used one with capacitive sensing. > >> - stopped dead within 1 character > > Guess what happens to the feed reel ? > > It continues to rotate, spiting tape all around the room ahead of the > reader :-).Well yes, I'd have thought that too. But I /don't/ remember it happening, and I /do/ remember wondering at the time how they avoided it.> The nice thing about paper tape that you don't necessary need a reader > to find out what is on the tape. I once was quite fluent with the > ASCII character table, so reading the paper tape visually was not that > hard, although slower than the TTY.Remember the "correctors"? A perspex block with eight holes, plus a rod inserted through the holes and paper to punch an extra hole in the paper. All holes punched was interpreted as "ignore this mistake" in the characterset. Or was that just with 5 channel papertape?
filling remaining array elements with fixed value
Started by ●June 12, 2014
Reply by ●June 17, 20142014-06-17
Reply by ●June 17, 20142014-06-17
On 17.6.14 11:05, Tom Gardner wrote:> On 17/06/14 08:30, upsidedown@downunder.com wrote: >> On Mon, 16 Jun 2014 10:41:59 +0100, Tom Gardner >> <spamjunk@blueyonder.co.uk> wrote: >> >>> On 16/06/14 08:13, Don Y wrote: >>>> I think when driving with a motor, you have more control over >>>> whether or not the tape ever "backs up". Relying on the sprocket >>>> holes to control the motor (speed) would be problematic as there >>>> is no guarantee that the tape won't buckle, fold, fall out of the >>>> slot, etc. so you've already got to have some local feedback on the >>>> motor/drive. >>> >>> I'm not sure what you mean by that. The 1000cps readers that >>> spat the tape 6' across a room into a hopper: >> >> I have used one with capacitive sensing. >> >>> - stopped dead within 1 character >> >> Guess what happens to the feed reel ? >> >> It continues to rotate, spiting tape all around the room ahead of the >> reader :-). > > Well yes, I'd have thought that too. But I /don't/ remember it > happening, and I /do/ remember wondering at the time how they > avoided it.In the Facit 5000 / 1000 characters/s reader there was a feed reel with a buffer bar keeping a loop in the tape. The buffer bar operated the feed reel brake when the loop got too large. IIRC, the still faster (2000 cps) Danish Regnecentralen reader used buffer loops and reel servos like open-reel mag tapes. -- Tauno Voipio>> The nice thing about paper tape that you don't necessary need a reader >> to find out what is on the tape. I once was quite fluent with the >> ASCII character table, so reading the paper tape visually was not that >> hard, although slower than the TTY. > > Remember the "correctors"? A perspex block with eight holes, plus > a rod inserted through the holes and paper to punch an extra hole > in the paper. > > All holes punched was interpreted as "ignore this mistake" in > the characterset. Or was that just with 5 channel papertape? > >
Reply by ●June 17, 20142014-06-17
On Tue, 17 Jun 2014 09:05:46 +0100, Tom Gardner <spamjunk@blueyonder.co.uk> wrote:>On 17/06/14 08:30, upsidedown@downunder.com wrote: >> On Mon, 16 Jun 2014 10:41:59 +0100, Tom Gardner >> <spamjunk@blueyonder.co.uk> wrote: >> >>> On 16/06/14 08:13, Don Y wrote: >>>> I think when driving with a motor, you have more control over >>>> whether or not the tape ever "backs up". Relying on the sprocket >>>> holes to control the motor (speed) would be problematic as there >>>> is no guarantee that the tape won't buckle, fold, fall out of the >>>> slot, etc. so you've already got to have some local feedback on the >>>> motor/drive. >>> >>> I'm not sure what you mean by that. The 1000cps readers that >>> spat the tape 6' across a room into a hopper: >> >> I have used one with capacitive sensing. >> >>> - stopped dead within 1 character >> >> Guess what happens to the feed reel ? >> >> It continues to rotate, spiting tape all around the room ahead of the >> reader :-). > >Well yes, I'd have thought that too. But I /don't/ remember it >happening, and I /do/ remember wondering at the time how they >avoided it.On our DDP-516 system the paper tape was mainly used for the OS loading and a parity error would cause an immediate stop of the tape, causing a lot of hassle. To recover, just try to reload tape. In systems that actually used paper tapes for data entry, there would have been frequent need to stop the tape at a specific location., so handling of the feed reel might have been quite important.>> The nice thing about paper tape that you don't necessary need a reader >> to find out what is on the tape. I once was quite fluent with the >> ASCII character table, so reading the paper tape visually was not that >> hard, although slower than the TTY. > >Remember the "correctors"? A perspex block with eight holes, plus >a rod inserted through the holes and paper to punch an extra hole >in the paper. > >All holes punched was interpreted as "ignore this mistake" in >the characterset. Or was that just with 5 channel papertape?It was definitively available on 8 channel paper tapes, since the RSX-11 terminal driver contained a mode to ignore the 377 (octal) punches.
Reply by ●June 17, 20142014-06-17
In article <lnm4p7$uhi$1@speranza.aioe.org>, this@is.not.me.com says...> > On 6/15/2014 11:53 PM, upsidedown@downunder.com wrote: > > On Sun, 15 Jun 2014 16:48:40 -0700, Don Y<this@is.not.me.com> wrote: > > > >>> While installing a 300 MB 14" SMD drive (the same size of an washing > >>> machine), my toe went under this device and it was not very well for a > >>> month or two :-). > >> > >> Yeah, when I was in school, I used to have access to the "junk > >> room" at DEC's facility (Maynard?). It was always amusing to > >> imagine what the "events" were like that led to those machines > >> being trashed (disk *crash*). > >> > >> "Holy Sh*t! Did you hear *that*?" > > > > It is an awful sound :-). > > From the damage done to the enclosure, it must be *really* violent! > But, then again, there's a sh*tload of mass moving at a pretty > high (angular) velocity! > > > After that you start to listen to the various drives to hear any > > abnormal sounds.Having worked at DEC facilities in UK, seeing 14inch platters that have had head crashes is quite spectacular considering how smooth they start. Remembers an RM03 multiple platter drive and main drive that estimated to stsrt head crash at 11pm, by 8:30am it was stopped as was continually trying to find good blocks to log errors. When taken apart instead of smooth flat brown surface it was pitted and shiny aluminimum. Yes it was brown as in those days the magnetic coating was brown, unlike the shiny disks now adays. -- Paul Carpenter | paul@pcserviceselectronics.co.uk <http://www.pcserviceselectronics.co.uk/> PC Services <http://www.pcserviceselectronics.co.uk/pi/> Raspberry Pi Add-ons <http://www.pcserviceselectronics.co.uk/fonts/> Timing Diagram Font <http://www.badweb.org.uk/> For those web sites you hate
Reply by ●June 17, 20142014-06-17
In article <f2svp9td3a31dsioj29okf6ih2sb7johqb@4ax.com>, upsidedown@downunder.com says...> > On Mon, 16 Jun 2014 19:40:39 +0000, Morten Reistad <first@last.name> > wrote: > > >Was it an RP07?.....> > The RP07 was non-removable (Winchester style) drive with a > replaceable HDA (Head Disk Assembly). The rotating platters might have > been a few kilograms, the whole HDA perhaps 20 kg and the whole drive > much more than that. If the platters really stopped in a millisecond > i.e. 1/16 of a rotation, transferring the angular momentum to the HDA, > which no doubt broke loose from the drive starting to rotate. > > Apparently there were no people in the room, since there would have > been injuries. > > Computing was dangerous in the past with shrapnels from failing disks, > deep scars due to fast paper tapes, crushed limbs due to heavy > equipment, electrocution from anode and mains voltages etc.Hmm remembers days of similar RP06 (with removable packs), one system operator move the same pack between 3 drives, before somebody stopped him from putting the mangled disk pack to crash another drive. They were floor standing washing machines, 3 phase supply AFAICR. Seen one be pushed too far on lorry tail lift and gravity unloaded them. Nice big crunch... Remember recall on a tape drive (type that was top half of full 19in rack) because hinge pins were too short. Field Service open drive for maintenance and drive topples to ground. You do not try and catch something with that size of solid aluminium casting base, large motors and vacuum pumps on the back. Mind you the Heathrow warehous had habit of not unloading the systems from planes correctly and end up with system on tarmac. -- Paul Carpenter | paul@pcserviceselectronics.co.uk <http://www.pcserviceselectronics.co.uk/> PC Services <http://www.pcserviceselectronics.co.uk/pi/> Raspberry Pi Add-ons <http://www.pcserviceselectronics.co.uk/fonts/> Timing Diagram Font <http://www.badweb.org.uk/> For those web sites you hate
Reply by ●June 17, 20142014-06-17
On Tue, 17 Jun 2014 13:31:20 +0100, Paul <paul@pcserviceselectronics.co.uk> wrote:>In article <f2svp9td3a31dsioj29okf6ih2sb7johqb@4ax.com>, >upsidedown@downunder.com says... >> >> On Mon, 16 Jun 2014 19:40:39 +0000, Morten Reistad <first@last.name> >> wrote: >> >> >Was it an RP07? >..... >> >> The RP07 was non-removable (Winchester style) drive with a >> replaceable HDA (Head Disk Assembly). The rotating platters might have >> been a few kilograms, the whole HDA perhaps 20 kg and the whole drive >> much more than that. If the platters really stopped in a millisecond >> i.e. 1/16 of a rotation, transferring the angular momentum to the HDA, >> which no doubt broke loose from the drive starting to rotate. >> >> Apparently there were no people in the room, since there would have >> been injuries. >> >> Computing was dangerous in the past with shrapnels from failing disks, >> deep scars due to fast paper tapes, crushed limbs due to heavy >> equipment, electrocution from anode and mains voltages etc. > >Hmm remembers days of similar RP06 (with removable packs), one system >operator move the same pack between 3 drives, before somebody stopped >him from putting the mangled disk pack to crash another drive.These 14" disk packs (such as RP05/RP06) disk are really heavy, In practice you have to lift into the top of the "washing machine" single handed and screw it to the spindle. Our main operator, a tiny lady (must be 80+ today) had some real problem moving around with these heavy 14" disk packs, so by gentlemen's agreement all the disk changes were rescheduled to the evening shift. One case in which I know the reason of the head crash: A 14" pack was moved from a site in the opposite side of the town in winter times. The car did not warm much in that time and when the disk pack was moved into the computer room with high humidity, some water droplets were accumulated on the disk surfaces, and when inserted into the disk drive _screeek_ occurred :-(. After that, the rule was to move the disk pack into the office environment of the target building, then wait a few hours, before moving the warmed up disk pack into the 50 % RH of the computer room.
Reply by ●June 17, 20142014-06-17
On Tue, 17 Jun 2014 09:05:46 +0100, Tom Gardner wrote:> Remember the "correctors"? A perspex block with eight holes, plus a rod > inserted through the holes and paper to punch an extra hole in the > paper. > > All holes punched was interpreted as "ignore this mistake" in the > characterset. Or was that just with 5 channel papertape?Not just. That's an ASCII DEL character. Mel.
Reply by ●June 17, 20142014-06-17
On 2014-06-17, Mel Wilson <mwilson@the-wire.com> wrote:> On Tue, 17 Jun 2014 09:05:46 +0100, Tom Gardner wrote: > >> Remember the "correctors"? A perspex block with eight holes, plus a rod >> inserted through the holes and paper to punch an extra hole in the >> paper. >> >> All holes punched was interpreted as "ignore this mistake" in the >> characterset. Or was that just with 5 channel papertape? > > Not just. That's an ASCII DEL character. >DEL is 0x7f. Was the 8th bit set due to parity ? (I also thought it was a special "rubout" character in which _all_ bits were punched regardless of the number of columns in use on the tape or the code set in use.) Simon. -- Simon Clubley, clubley@remove_me.eisner.decus.org-Earth.UFP Microsoft: Bringing you 1980s technology to a 21st century world
Reply by ●June 17, 20142014-06-17
On 17.6.14 21:40, Simon Clubley wrote:> On 2014-06-17, Mel Wilson <mwilson@the-wire.com> wrote: >> On Tue, 17 Jun 2014 09:05:46 +0100, Tom Gardner wrote: >> >>> Remember the "correctors"? A perspex block with eight holes, plus a rod >>> inserted through the holes and paper to punch an extra hole in the >>> paper. >>> >>> All holes punched was interpreted as "ignore this mistake" in the >>> characterset. Or was that just with 5 channel papertape? >> >> Not just. That's an ASCII DEL character. >> > > DEL is 0x7f. Was the 8th bit set due to parity ? > > (I also thought it was a special "rubout" character in which _all_ > bits were punched regardless of the number of columns in use on the > tape or the code set in use.) > > Simon.8 track tape often used even parity in text, so DEL and rubout were the same. On 5 channel tape all holes was letter shift, where extra ones were ignored, so it could be used as rubout. -- -Tauno Voipio
Reply by ●June 17, 20142014-06-17
On 17/06/14 21:31, Tauno Voipio wrote:> On 5 channel tape all holes was letter shift, where extra > ones were ignored, so it could be used as rubout.There were, of course, multiple incompatible 5 channel encodings. My first machine code program, in which I unknowingly reinvented the concept of a simple FSM, converted between two of them (the teleprinter we had at school and the Elliott teleprinter/computer we used at the local Tech College)
