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Mock up of reel to reel computer/ tape machine/VCR

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large_ghostman

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This isnt my project but i have been asked a question, someone i went to school with has a brother and its project time at school again. What they want to do is a kind of working mock up of a reel to reel main frame, the ideas so far are to use something from a old cassette player (wtf), or maybe VCR machine.

The reels will likely be smd component reels or something like that, turned probably by stepper motor. They want something that will turn both ways and just simulate that while being able to actually record simple data if needed/wanted. The only idea i came up with was a old cassette player head and the tape from it.

These things are ARK tech and i have barely seen one let alone know how they work!! So is it possible to record simple serial data onto tape like this using an old cassette player read/write head? If so where on earth do you dig up such things? Sounds almost like archeology to me :D, i am aware speed would be dire but thats ok, its a project where the mock up and moving reels alone would give them a good chance of a prize, but data from say a temp sensor being written and then read back would smash it.

Any thoughts? the age of the kid is 13 but they are allowed some help, i have said if i can find a way i would help them out with it as it actually sounds like a cool idea. We did consider punched cards but reel to reel is kind of iconic at the moment.
 

alec_t

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A VCR cassette (should still be plenty around in e.g. charity shops or granny's house) would give you both the tape and the spools. You could use the spools as cores of bigger diameter ones if you want something showy.
 

large_ghostman

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A VCR cassette (should still be plenty around in e.g. charity shops or granny's house) would give you both the tape and the spools. You could use the spools as cores of bigger diameter ones if you want something showy.
I better dig through some hieroglyphics and see how these things work :D.
 

dr pepper

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PDP 7's havent been around for a long time, so there isnt many original tape drives around.
You might be able to get hold of an old reel to reel audio tape player, but they have become trendy again so will probably be £££'s.
Cheapest way would be to make your own from some other old gear, 12" audio reels would look something like, the original tape I htink is 3/4" or maybe 1", audio tape is smaller maybe 3/8" cant remember, but you'd not see that.
 

JonSea

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Atari and Vic 20s used cassette recorders to store data....quite poorly in reality.

Long long ago and far far away, I adapted a 300 baud modem to record "logbook" information on one track of a 7 track instrumentation recorder (Racal Store 7). We were recording data from two triaxial accelerometers on shipboard rotating machinery. Recording the positions and gain settings allowed automating playback of the data in the office. A job taking 3 manweeks of manual labor was reduced to about 12 hours. Data quality was improved in the process because the computer running the tape recorder wouldn't start until all the required info was entered in. No more trying to guess which machine the data was recorded on when somebody forgot to write it down, or guessing at levels when something was missed.

I wrote the data to tape in plain ASCII, formatted as a table so it could easily be read back in the future with only a standard modem if need be. Our 60 second recordings allowed ample room for the required info and comments. An ASCII break was recorded at the beginning and end of each recording, as the modem could correctly identify that with the tape running forwards or backwards.

To play back the data, the computer started the recorder and read the log book info until a break signal was detected. The recorder was reversed, and the desired FFTs (as entered in the log info) were taken on each channel in turn, cycling the tape back and forth as needed.

I was im awe when I saw the system actually work the first time! It would process a reel of tape with no intervention, then make some noise for the reel to be changed. so much tedium relieved.

The picture show the Store 7 recorder which uses 1/2" tape and the HP85 computer used to control it in the field. The modem I adapted was an Atari acoustic modem, which I traded a box of 50 5.25" floppy disks for.

360_affdf39ec31efd03c5266b163a694f4a.jpg Running_HP_85_with_BASIC_listing _2012.jpg
 

dr pepper

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That brings back memories, my first computer program:
10 Print "Get Lost"
20 Goto 10
 

Les Jones

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Hi LG,
Audio tape recorders were used for data storage on home computers many years ago. They used frequency shift keying and the most common standard was call was called "Kansas city standard" Normal computer data recorders used NRZ (Non return to zero) then PE (Phase encoded.) then GCR (Group coded recording). These methods were used for the first few years I worked for DEC (Digital equipment corporation.).

Les.
 
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gophert

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Atari and Vic 20s used cassette recorders to store data....quite poorly in reality.

Long long ago and far far away, I adapted a 300 baud modem to record "logbook" information on one track of a 7 track instrumentation recorder (Racal Store 7). We were recording data from two triaxial accelerometers on shipboard rotating machinery. Recording the positions and gain settings allowed automating playback of the data in the office. A job taking 3 manweeks of manual labor was reduced to about 12 hours. Data quality was improved in the process because the computer running the tape recorder wouldn't start until all the required info was entered in. No more trying to guess which machine the data was recorded on when somebody forgot to write it down, or guessing at levels when something was missed.

I wrote the data to tape in plain ASCII, formatted as a table so it could easily be read back in the future with only a standard modem if need be. Our 60 second recordings allowed ample room for the required info and comments. An ASCII break was recorded at the beginning and end of each recording, as the modem could correctly identify that with the tape running forwards or backwards.

To play back the data, the computer started the recorder and read the log book info until a break signal was detected. The recorder was reversed, and the desired FFTs (as entered in the log info) were taken on each channel in turn, cycling the tape back and forth as needed.

I was im awe when I saw the system actually work the first time! It would process a reel of tape with no intervention, then make some noise for the reel to be changed. so much tedium relieved.

The picture show the Store 7 recorder which uses 1/2" tape and the HP85 computer used to control it in the field. The modem I adapted was an Atari acoustic modem, which I traded a box of 50 5.25" floppy disks for.

View attachment 112654 View attachment 112655
Wonderful memory.
I was trained to clean, setup, calibrate a GC-Mass Spec that was controlled by one of those HP "computers" and a thermal paper printer.
 

AnalogKid

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Let's tune up the specs a bit. If you use SMT reels, you cannot record or play back data. Also, if you are going for at least the look of old computer tape drives, then a videocassette will not look anything at all like that. With an exposed audio cassette you can see the two hubs turning, and the oxide side of the tape is exposed so you could get data on and off of it if you wanted.

While "professional" data drives using audio cassettes used saturated recording techniques, most of the old systems were in the hobbyist realm and used audio tones, similar in concept to a 300 baud modem, called the Kansas City Standard.

ak
 

gophert

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I have an old Lloyd's reel to reel personal recording unit for you if needed.

Same as this one (not my video)

 

large_ghostman

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Thx for the info guys, this is a funny project for me. Many of you here helped my projects when i did the same course at school, so when my mate said his younger 13 year old brother needed a hand.... I thought back to four years ago and all the help i got on many a mad school project, feels really odd being the helper now!

Normal rules apply, i cant build it for him i can only assist and help. I can do a little of the code, 4 years ago this wasnt allowed but they relaxed that because so much duino code around its pointless trying to police it.

Hi LG,
Audio tape recorders were used for data storage on home computers many years ago. They used frequency shift keying and the most common standard was call was called "Kansas city standard" Normal computer data recorders used NRZ (Non return to zero) then PE (Phase encoded.) then GCR (Group coded recording). These methods were used for the first few years I worked for DEC (Digital equipment corporation.).

Les.
Hi les
I know a little about NRZ FSK from my long ago drone project, will go look that up again. I did wonder if normal serial at low baud could be used, its not essential to be authentic, but spending some time looking around it seems RS232 would be a mare on tape. Not too sure how he is going to show the data came from the computer to the tape, then run the tape to show its recorded.... not my problem though :D.

While "professional" data drives using audio cassettes used saturated recording techniques, most of the old systems were in the hobbyist realm and used audio tones, similar in concept to a 300 baud modem, called the Kansas City Standard.

ak
Bah 300 is 60 higher than i thought of! I thought he might get away with 240, but 300 would be awesome, he could call it turbocharged super fast data streaming. :p, sometimes i miss doing this school projects! I should get him to join here, Kevin is a tinkerer like most of us. He fixed his PS4 when it broke so at 13 i think he would be a good member :D.

I have an old Lloyd's reel to reel personal recording unit for you if needed.

Same as this one (not my video)
Thx i might need to take you up on that, we do have a VIC 20 but its got the floppy drive and no tape drive now. Looking around the junk shed i cant find a single cassette drive or VCR!! But i have found unopened cassettes!! Sti8ll blank and from 1981! in the cellophane.

As i said he could fake it and win, most the project are bog standard LED torches etc etc etc, which is why i loved his idea. Totally off the wall like mine used to be, and getting it to work in some way would blow the other stuff out the water. What made me laugh was when i went to meet him, he said to me... Your the guy that built the final year drone arnt you? the one with the pictures in the glass case at school. It felt like royalty lmao, so i said yeah i was as mad as you are.

First thing i have to do is wean him off the lead free solder! I will look up the KANSAS standard and see what can be done. I am over there Thursday so i will try and get him to join the forum.
 

Les Jones

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Hi LG,
Here is a link to some information on Kansas city cassette interfaces. The first link to the "Byte magazine" article looks a good place to start. It looks more complex than the interface I made many (Over 40) yeras ago. I think mine was just a 2.4Khz oscillator with a divider down to 1.2Khz. I think the incoming data was clocked into a flipflop with one edge of the 1.2 Khz signal to synchronise it with that waveform. I think the synchronised data then just selected the two frequencies.

Les.
 

large_ghostman

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I found a VIC20 game on tape!! I might try and play that in a cassette player and see what the signals look like. Big problem being the VIC20 used a non standard speed from info i have found.
First job is to track down a tape player! Alot like hunting unicorns where i am :D.

I found a CD player designed to be worn while jogging..........someone didnt think that through enough lol, makes as much sense as strapping a vinyl player to your back then jogging:p. Punch cards would of been easier to do! I will go see him later in the week and find out which way he wants to go, i emailed him and explained roughly what we had in mind, he has replied asking loads of questions. Asked me what 8 track was..... erm one more than 7 is about the best i can do.

Thats a good link, biggest problem is finding what my terminal runs at lol..... Actually joking aside it looks like a good way to do it, FSK is one the protocols i used on the drone with the smart metering kit. 300 baud is going to take a while to do much.

I have visions of snails powering 1970 main frame tape reels! How did people stay awake loading games at those speeds?
 
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Les Jones

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Hi LG,
In one context 8 track was a cartridge tape system for playng music in the car (About 50 yeras ago.) There were very few (If any ) units to record these tapes as it was aimed at selling pre recorded tapes. Being mean I modified a player to record. The tape was an endles loop and the head assembly was moved to 4 positions (4 x 2 tracks for stereo) to effectivly get 4 times the length of tape. The 1/2" computer tape drives I worked on had 8 data track plus a parity track so they actualy had 9 tracks.

Les.
 

tomizett

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If you could get one, I think an open-reel tape 1/4" tape machine hooked up to a standard telephone modem should work (at least, do something interesting). As someone said, though, they're probably getting collectable so a working one may be expensive to buy. You could make a working demo without modifying the tape machine though, so perhaps someone has a working example they could lend you for the duration?
 

large_ghostman

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I need to email him and see exactly what he wants to do, i think if we can read and record like a data logger, and look a bit like a reel to reel mainframe, thats most of it done. Its not my project so i need to ask, but reading and writing data is not looking to simple. Like you say just getting hold of a tape recorder is not easy.
 

unclejed613

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i used to repair mainframe tape drives, including cassette drives. you could use something like FLDigi to store data as audio, and retrieve it if you can learn the scripting language for FLDigi. there are many modems to choose from, including "plain old" FSK (up to 300 baud). some of the more modern modems can do well over 1200baud. you would need to get something with the functionality of a mainframe tape drive (the ability to control the tape position to BOR or BOF (beginning of file or beginning of record) after reading a directory block header, so the drive would need to be controlled (all functions, Rec. Play, FF, REW, CUE) you would also need some type of rotary encoder to keep track of where on the tape the current position is. either that or the tape would have to be formatted in blocks, with a series of low frequency bursts that would be counting during a FF or REW operation.
 

dr pepper

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Karen ortons 'notoof' device transmits 'duino data pin states & analogue pin values over Fm broadcast using fsk, you might be able to borrow the bit of code that generates the tones.
http://www.techlib.com/area_50/Readers/Karen/micro.htm#Notoof
A couple of years back I got a pic to send Tty over fsk, it was simple to do I just used the Pwm module and switched freq's using a timer, the vids naff but you can hear the tones:
 

gophert

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I you want to keep everything "old school", use a XR2206 Function Generator chip - it has a built-in FSK capability.
 

KeepItSimpleStupid

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OK. my turn. Kinda grew up in the ERA. Magtapes used vacuum and I think the lowest density was 800 bpi, then i remember 1600 and some huge 6550 bpi/
They "probably" did that so the tape ran on a cushion of air and could start/stop fast. I only operated an 800/1600 bpi drive.

But one of the cooler things was a DEC TAPE. See https://en.wikipedia.org/wiki/DECtape

These didn't use vacuum. They used a wide tape. They also tended to forward and reverse a lot until we wrote programs that could copy a DEC TAPE faster. There was an interleave factor. If you wrote/read the tape every 4 blocks, it would run in one direction. You may have been able to write in the reverse direction every 4 blocks and essentially copy the tape with two CW passes and two CCW passes without the spastic backing up to find it;s place again.

Lots of stuff in the references. Also used the cassettes, as in TU58 drive. Hewlet-Packard's HP 85/86 computers had a cassette based drive,

Early consumer computers used an audio cassette tape to store programs. I do think this was FSK like 103 modems.
 
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