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#1 2015-10-09 16:19:34

bbraun
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Registered: 2014-05-29
Posts: 1,064
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Using Cassette ports with iPhone

There's lots of sites around about using modern devices to play audio files, like gameserver and related diskserver.  But saving data to the cassette/iphone is a bit different, and AFAIK requires making your own cable.

The iPhone's TRRS (headphone jack) pinout is as follows:
Tip: Left audio channel
Ring1: Right audio channel
Ring2: Ground
Sleeve: Mic

There are a couple different sources of adapters that will split the audio out and mic channels into separate cables so they can be plugged into the Apple II.  Just be careful because there are several different pinouts for the TRRS connector, and Apple's is kind of wonky.
But the trick is the iPhone will only switch to using the TRRS jack's mic if there is roughly 1600 ohms impedance on the line, which isn't present when plugging into the Apple II's cassette out port.  Essentially you need to add 1600 ohms resistance inline on the mic signal.  I didn't have a 1600 ohm resistor, so I used a 1k and a 681 ohm resistor in series, and it seems to work:
45.jpg

Using iOS9 on an iPhone5, Voice Memos seems to work just fine.
On the Apple II, I entered a simple basic program:
10 PRINT "HELLO"
20 GOTO 10

Then on the iPhone in Voice Memos hit the Record button.  On the Apple II, type SAVE.  The Apple will wait a short while, beep, then wait a while, and then there will be a final beep when it is done.
Type NEW to clear out the program from memory so loading from "tape" can be verified.  Verify it has been cleared by typing LIST.  The output should be empty.

To load the program again, on the Apple, type LOAD.  On the iPhone's Voice Memos, hit play.  After a short delay (roughly the same delay as between typing SAVE and the subsequent first beep), the Apple will beep, wait, and then a final beep when it is done loading.
Type LIST to verify the program was loaded correctly.

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#2 2015-10-09 20:09:38

jt
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From: Bermuda Triangle, NC USA
Registered: 2014-05-21
Posts: 1,404

Re: Using Cassette ports with iPhone

Cool! cool Never did use a tape though, the wonderful ex bought me the FDD for the Commodore 64 for my birthday not long after I bought it, a Red Baron cart and a pair of wireless joysticks.

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#3 2015-10-09 21:26:29

Eudimorphodon
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Registered: 2014-09-02
Posts: 525

Re: Using Cassette ports with iPhone

Hm. Wonder if the same pinout works on latter-day Macbooks that only have the single audio jack.


Flap Different.

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#4 2015-10-09 21:57:24

bbraun
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Registered: 2014-05-29
Posts: 1,064
Website

Re: Using Cassette ports with iPhone

Yeah, I never used cassettes for data storage back in the day either.  But, it's actually a pretty handy mechanism for modern retrocomputing IMO.  Conveniently saving whatever I'm working on to a modern device, and I can navigate the list of files on the modern device a little more easily.

It looks like at least the retina macbook pros have the same TRRS pinout as the iphones, so at least it's (now) consistent within Apple products.

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#5 2015-10-09 23:34:35

mcdermd
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From: Corvallis, OR
Registered: 2014-05-12
Posts: 961
Website

Re: Using Cassette ports with iPhone

We used cassettes on the school's Apple IIs circa 1979-1980. Later I had a friend with a Coleco ADAM that stored on cassettes (and, more importantly, played ColecoVision game cartridges).


Daily Drivers: 27" iMac 2.8 GHz Quad-Core i7 (Late 2009), 21.5" iMac 2.7GHz Quad-Core i5 (Late 2013), 11" Macbook Air 1.6 GHz i5 (Mid-2011)
See the restored heroes here.

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#6 2015-10-09 23:45:29

Eudimorphodon
Member
Registered: 2014-09-02
Posts: 525

Re: Using Cassette ports with iPhone

Well, technically the ADAM's storage system wasn't regular cassettes; to make a regular cassette work in those drives you had to drill a set of holes in the case and use a shareware formatter program that required a second drive. wink

(The ColecoVision system was similar to the "Stringy Floppy" and other proprietary tape systems that allowed random access sort of like a disk drive. Coleco used parts from regular cassette mechanisms to save money but added the pegs and made it impossible for the regular system to format a tape so they could make money selling media.)


Flap Different.

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#7 2015-10-10 03:44:47

tkc8800
Member
From: Adelaide
Registered: 2015-10-03
Posts: 25
Website

Re: Using Cassette ports with iPhone

I've used the Apple Game server with my Apple II Plus and iPhone 4S, it's quite a buzz to see it work.  Never tried saving anything though, I recall reading that you needed a different cable.

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#8 2015-10-10 04:34:34

iMic
Administrator
From: Adelaide, Australia
Registered: 2014-05-12
Posts: 882
Website

Re: Using Cassette ports with iPhone

bbraun wrote:

It looks like at least the retina macbook pros have the same TRRS pinout as the iphones, so at least it's (now) consistent within Apple products.

Those Apple headsets are usable with just about any Apple device, including iPhone, iPod, MacBook Pro, MacBook Air, MacBook and iMac among others, so it does appear to be standardised.


I used ADTPro on a MacBook Pro with separate audio inputs and outputs to transfer ProDOS to an Apple II Plus. Took 15 minutes to transfer the contents of a single 5.25" floppy, but it worked, and one the data was transferred the subsequent loads from floppy were extremely quick.


Resident Professor of Alternative Methodology
Faculty of Macintosh Restorations & Modifications - "It works, let's fix it!"

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#9 2015-10-10 04:56:22

mcdermd
Member
From: Corvallis, OR
Registered: 2014-05-12
Posts: 961
Website

Re: Using Cassette ports with iPhone

tkc8800 wrote:

I recall reading that you needed a different cable.

Which is what bbraun detailed above wink


Daily Drivers: 27" iMac 2.8 GHz Quad-Core i7 (Late 2009), 21.5" iMac 2.7GHz Quad-Core i5 (Late 2013), 11" Macbook Air 1.6 GHz i5 (Mid-2011)
See the restored heroes here.

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#10 2015-10-10 05:33:52

tkc8800
Member
From: Adelaide
Registered: 2015-10-03
Posts: 25
Website

Re: Using Cassette ports with iPhone

mcdermd wrote:
tkc8800 wrote:

I recall reading that you needed a different cable.

Which is what bbraun detailed above wink

Just confirming, not repeating.

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