*TAPE baud rates

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AndyF
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*TAPE baud rates

Post by AndyF » Fri Jul 20, 2018 4:33 pm

I really was not sure where to post this, so for the moment into 'Misc' seemed best, at least until a kindly passing moderator decides to move it if appropriate.

Anyway, I've wondered for ages why there's a 300 baud rate as well as the 1200 :-k , I never really had many problems 'back then' loading tapes on any platform, although I did have a decentish tape player for the computers. I did try a few variants and always settled on one type but that's something for another topic as I need to collect pics and specific model details. Other computers from the time period used similar baud rates to 1200

I can only really see a use of the 300 tape speed for really bad setups, perhaps reel-to-reel ? :shock: , but I suspect (not having really used one properly although we did have them at "skool" for language lessons) reel-to-reel are probably higher quality tape than conventional tapes, at least until the dust monster gets at them.

So the question is why is there a 300 baud tape speed ? And secondly was there any software that used it ? I can't think of or find any. Attached are my silly "flecks2" listings, both as standard 1200 and at 300 as well. I've put them into a single .zip for the moment as .uef tape images are not permitted uploaded attachment file types yet.
flecks at 300 and 1200.zip
(1.04 KiB) Downloaded 8 times
I simply did a *TAPE3 then (just for the sake of it) *OPT1,2 to see more details then saved, next set it back with *TAPE12 and saved again.
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Re: *TAPE baud rates

Post by CMcDougall » Fri Jul 20, 2018 5:22 pm

To make a backup that will last 4x longer, as less error prone.
Similar to a 40T disc will outlive a 80T.

Some tape protection used it to fool the hacker from tape to disc, usually hidden in REM statements & a false shown CH."main"

Reel to Reel recorders piss all over CDs, as a much higher frequency response. I have a Sony & it's built to last, & still works 100% 40yrs on :)
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Re: *TAPE baud rates

Post by johnkenyon » Fri Jul 20, 2018 5:24 pm

The answer might be here:
https://en.wikipedia.org/wiki/Kansas_City_standard

The BBC tape interface is based on CUTS, and 300bd is the lowest common denominator.

I don't know if 300baud was more reliable or not - by the time I was hacking around on BBC's my stuff was either stored on the college's L3 Econet FS, or on my own floppies.

It's also worth noting that the clock for the ACIA when loading is generated by the ULA from the incoming stream. So in theory selecting 300/1200 baud only changes the transmission rate.

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Re: *TAPE baud rates

Post by 1024MAK » Fri Jul 20, 2018 5:45 pm

No, no, no, no!
It's actual purpose is so you can enjoy the longer time for the program to load :mrgreen: :lol:

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Re: *TAPE baud rates

Post by CMcDougall » Fri Jul 20, 2018 6:16 pm

viewtopic.php?f=32&t=14573#p195160
this is the only published 300baud backup on sideB , not found anymore on the mass of tapes I've archived....
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Re: *TAPE baud rates

Post by AndyF » Fri Jul 20, 2018 9:19 pm

Thanks all.

As I say I'd not come across anything that needed 300 , figuring if it did then the first part would be at 1200 (perhaps a tiny bit to just do a speed change) then the rest at 300.

I see what is meant by offering it at 300, in the same case you could then also offer it at say 2400 as well, to be fair a decent (back then) mono deck would of been completely fine as its then only approaching commerical loading schemes for other platforms (early ZX and AMS Speedlock and one of the Amstrad loader speeds), I forget which and I don't know about the CBM wide range of loaders)

Slower speed I'd agree might be fun where there is either a decent "loading tune" or perhaps a mini-game to play while the main one loads.

:)
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Re: *TAPE baud rates

Post by vanekp » Sat Jul 21, 2018 8:24 am

1024MAK wrote:
Fri Jul 20, 2018 5:45 pm
No, no, no, no!
It's actual purpose is so you can enjoy the longer time for the program to load :mrgreen: :lol:

Mark
:lol: :lol: :lol: =D> =D> =D>
Your probably right :D
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Re: *TAPE baud rates

Post by Rich Talbot-Watkins » Sat Jul 21, 2018 10:25 am

My first computer was an Oric-1, which could load/save to tape at 2400 or 300 baud. 2400 baud never ever worked properly, so I always recorded at 300 baud, which even sounded slow.

I never quite understood the Beeb cassette hardware. So the ULA has baud rate settings for transmit and receive, and the ACIA has a clock divider. For tape, the ULA is set to 19200 baud receive and 300 baud transmit, with the ACIA dividing by 16 to supposedly give 1200 baud. But the ULA ignores the receive rate for cassette mode (and always uses 19200), and when saving, surely 300 baud divided by 16 is something very slow indeed!

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Re: *TAPE baud rates

Post by Elminster » Sat Jul 21, 2018 11:07 am

I always think I would have been a better programmer now if I had floppy instead of tape as a youth. Saving stuff was just a pain when writing code. I think my first floppy was on a spectrum +2 around 15 years young, my Electron not at all.

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Re: *TAPE baud rates

Post by AndyF » Sat Jul 21, 2018 1:00 pm

Rich Talbot-Watkins wrote:
Sat Jul 21, 2018 10:25 am
My first computer was an Oric-1, which could load/save to tape at 2400 or 300 baud. 2400 baud never ever worked properly, so I always recorded at 300 baud, which even sounded slow.
I do have an Oric Atmos that now works however there is no video output (yet) the composite signal I hoped to use was not strong enough (apparently after a bit of research anyway) so I may have to make a powered RGB lead or perhaps try a single BC (I think) type transistor to erm 'amplify' the composite out (modulator input) signal a fraction. I know the machine works as the keyboard noises are present and typing in SOUND type commands produces well sound, 'ZAP' works too! :lol:
Rich Talbot-Watkins wrote:
Sat Jul 21, 2018 10:25 am
I never quite understood the Beeb cassette hardware. So the ULA has baud rate settings for transmit and receive, and the ACIA has a clock divider. For tape, the ULA is set to 19200 baud receive and 300 baud transmit, with the ACIA dividing by 16 to supposedly give 1200 baud. But the ULA ignores the receive rate for cassette mode (and always uses 19200), and when saving, surely 300 baud divided by 16 is something very slow indeed!
I still do not :( Only really starting to get properly into tape loading specifics and then on another platform.
Elminster wrote:
Sat Jul 21, 2018 11:07 am
I always think I would have been a better programmer now if I had floppy instead of tape as a youth. Saving stuff was just a pain when writing code. I think my first floppy was on a spectrum +2 around 15 years young, my Electron not at all.
Hopefully not the 3" disks, they were not too bad apart from iirc they used to cost about 2.99 each, the few that I purchased. Expensive. I do have a working +3 now with an internal 3.5, electrically its fine, cosmetically its not though. Interestingly (or not) you can format with a third party utility the disks to 720 odd Kb (built in formatter will leave them at 180K or so) but the interesting thing is +3DOS supports properly the 720Kb format as well as a few others too, just no built in formatter for it. Not a big issue.

'Back then' I was already fearful of microdrives realibilty and the like, and nearly got one of the much reduced in price WafaDrives when they were offered cheaply in one of the mags, possibly Y.S iirc. Trouble was they ate something like 8kb at the top end of memory rather than trying some clever shadowing tricks so they were not quite as good as they might of been. I seem to remember they were quite noisy too but reasonably fast. Not as noisy as microdrives though.
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Re: *TAPE baud rates

Post by Elminster » Sat Jul 21, 2018 1:17 pm

No I had a +2 with dual cumana 3.5 inch drive unit, never had a +3

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Re: *TAPE baud rates

Post by AndyF » Sat Jul 21, 2018 2:54 pm

Elminster wrote:
Sat Jul 21, 2018 1:17 pm
No I had a +2 with dual cumana 3.5 inch drive unit, never had a +3
Relatively rare and expensive 'back then' ! :)
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Re: *TAPE baud rates

Post by Elminster » Sat Jul 21, 2018 3:48 pm

AndyF wrote:
Sat Jul 21, 2018 2:54 pm
Elminster wrote:
Sat Jul 21, 2018 1:17 pm
No I had a +2 with dual cumana 3.5 inch drive unit, never had a +3
Relatively rare and expensive 'back then' ! :)
Yep. I had snapshot interface and swiped my dad floppy drive when he move from a QL to a PC. I quite liked the microdrives at he time, but obvious were fairly niche.

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Re: *TAPE baud rates

Post by scruss » Sun Jul 22, 2018 1:55 pm

AndyF wrote:
Fri Jul 20, 2018 4:33 pm
Anyway, I've wondered for ages why there's a 300 baud rate as well as the 1200 :-k
Those of us who may have allegedly traded BBC programs over CB radio are very thankful for 300 baud.

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Re: *TAPE baud rates

Post by AndyF » Sun Jul 22, 2018 5:02 pm

scruss wrote:
Sun Jul 22, 2018 1:55 pm
AndyF wrote:
Fri Jul 20, 2018 4:33 pm
Anyway, I've wondered for ages why there's a 300 baud rate as well as the 1200 :-k
Those of us who may have allegedly traded BBC programs over CB radio are very thankful for 300 baud.
That's a thought. That and when I vaguely remember a TV program where they tried to transmit the tape audio as part of the programme.
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Re: *TAPE baud rates

Post by scruss » Sun Jul 22, 2018 5:27 pm

Yup, I remember the TV broadcasts. I also remember a weird little optocoupler embedded in a sucker that you could stick to the top of the screen. It used an embedded photodiode to decode software transmitted by flickering the corner of the screen

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Re: *TAPE baud rates

Post by AndyF » Sun Jul 22, 2018 6:12 pm

scruss wrote:
Sun Jul 22, 2018 5:27 pm
Yup, I remember the TV broadcasts. I also remember a weird little optocoupler embedded in a sucker that you could stick to the top of the screen. It used an embedded photodiode to decode software transmitted by flickering the corner of the screen
I don't remember that part, being quite young at the time. I do recall trying to hold my tape player (recording) next to the speaker with the volume up high(ish) to get a recording but it was too poor to play back. :oops:

I seem to remember that they also covered other platforms too, as at that time I only had a Spectrum, although I did have occasional access to a model 'B too, so its possible I tried to record a ZX transmission I guess, but it may well of been a 'B one.
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Re: *TAPE baud rates

Post by 1024MAK » Mon Jul 23, 2018 5:29 am

Channel 4 on either Saturday or Sunday mornings (forget which, may have been both) transmitted Elk/BBC, ZX Spectrum and maybe programs for other machines on the audio channel.

I was successful in recording some for my ZX Spectrum including a game from Ocean called Pud Pud (but not the final version that they ended up releasing). I'm sure I recorded other programs, but can't remember any more.

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Re: *TAPE baud rates

Post by Kazzie » Mon Jul 23, 2018 1:31 pm

For reference, The Acorn System 1 used 300 baud (only) for its cassette interface (as presumably did the System 2, using the same board as the 1).

Edit: so did the Atom, having flicked through a PDF of "Atomic Theory and Practice".

So the Beeb's 300 baud mode probably exists for the same reason that Acorn used an (old by then) 8271 chip for the floppy interface: it's what they already had working with the System and Atom line. (1200 baud was part of the BBC's spec, so they had to add that.)
Last edited by Kazzie on Mon Jul 23, 2018 1:46 pm, edited 4 times in total.
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Re: *TAPE baud rates

Post by AndyF » Mon Jul 23, 2018 8:17 pm

Kazzie wrote:
Mon Jul 23, 2018 1:31 pm
For reference, The Acorn System 1 used 300 baud (only) for its cassette interface (as presumably did the System 2, using the same board as the 1).

Edit: so did the Atom, having flicked through a PDF of "Atomic Theory and Practice".

So the Beeb's 300 baud mode probably exists for the same reason that Acorn used an (old by then) 8271 chip for the floppy interface: it's what they already had working with the System and Atom line. (1200 baud was part of the BBC's spec, so they had to add that.)
That makes sense now you've mentioned System 1 and perhaps the Atom too, I'd not even considered looking at what tape baud rate it used. Had issues with one Atom emulator a while back so not really gone any further with it as of yet.

You do raise a good point about the 8271 interface too, as (if memory serves, I've not looked this up honest) the 8271 was meant originally for the eight inch drives I think, certainly the date codes on them are something like '78 which does about fit this theory.

Having said that I've not seen a 'B with an '8' plugged in, although I recall seeing some third party 3 inch unit, not a brilliant choice unless you want some kind of data sharing with either later Spectrums and/or Amstrad machines perhaps. Mind you despite the low capacity of the 3" units their cases were quite hardy, shame there was no protection shutter on the media 'hole' though! Oops!

EDIT... I guess my next logical question really , turbo tape loading as in loading at say 2400 instead. How practical on a 'B to do this ? Unsure where the tape routines reside although they are going to be in the OS aren't they ? Not in the Basic rom, otherwise fiddling about with the timing constants would achive this, for instance copying the 'load' routine out into ram then running it from there.
Last edited by AndyF on Mon Jul 23, 2018 8:22 pm, edited 1 time in total.
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Re: *TAPE baud rates

Post by IanS » Mon Jul 23, 2018 8:28 pm

AndyF wrote:
Mon Jul 23, 2018 8:17 pm
Mind you despite the low capacity of the 3" units their cases were quite hardy, shame there was no protection shutter on the media 'hole' though!
All the 3" discs I own have a shutter.
http://www.obsoletemedia.org/3-inch-com ... oppy-disk/
The 3-inch floppy has a more rigid casing than a 3.5-inch microfloppy, and the metal shutter is opened by a sliding plastic tab.

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Re: *TAPE baud rates

Post by AndyF » Mon Jul 23, 2018 8:38 pm

IanS wrote:
Mon Jul 23, 2018 8:28 pm
AndyF wrote:
Mon Jul 23, 2018 8:17 pm
Mind you despite the low capacity of the 3" units their cases were quite hardy, shame there was no protection shutter on the media 'hole' though!
All the 3" discs I own have a shutter.
http://www.obsoletemedia.org/3-inch-com ... oppy-disk/
The 3-inch floppy has a more rigid casing than a 3.5-inch microfloppy, and the metal shutter is opened by a sliding plastic tab.
The only ones I can recall were these:

http://www.obsoletemedia.org/3-inch-com ... ppy-blank/

My memory might be playing tricks on me then but I could of sworn that the media gap in the case and the track 'hole' were not shuttered. It may be a case me being wrong here (I blame the heat its 32°c at my PC desk currently) :oops:
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Re: *TAPE baud rates

Post by IanS » Mon Jul 23, 2018 9:01 pm

AndyF wrote:
Mon Jul 23, 2018 8:38 pm
My memory might be playing tricks on me then but I could of sworn that the media gap in the case and the track 'hole' were not shuttered.
https://www.youtube.com/watch?v=K7Xlx5qRszU

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Re: *TAPE baud rates

Post by CMcDougall » Mon Jul 23, 2018 9:06 pm

viewtopic.php?f=3&t=13972&p=184563#p184563
^this will answer your "top speed" baud rate.
It was not consistent across my different machines, so 1500 top's.
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Re: *TAPE baud rates

Post by scruss » Tue Jul 24, 2018 3:59 am

IanS wrote:
Mon Jul 23, 2018 9:01 pm
AndyF wrote:
Mon Jul 23, 2018 8:38 pm
My memory might be playing tricks on me then but I could of sworn that the media gap in the case and the track 'hole' were not shuttered.
https://www.youtube.com/watch?v=K7Xlx5qRszU
Yes, very shuttered. I occasionally sent (but more frequently received) 3" disks mailed with nothing but a label on them: no envelope, all data intact. They were good little disks: quick and reliable. They're a bit dismal as they age, as the motor drive is through a narrow rubber belt which is prone to perishing.

There were very cheap 3" disks with no shutter. They were very unreliable.

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