[Question]
  [
Write a script that outputs `A` to stdout infinitely.
There should be no newlines or separators between the characters.
Standard loopholes apply.
This is [code-golf](/questions/tagged/code-golf "show questions tagged 'code-golf'"). The shortest solution in each language wins.
  
[Answer]
# x86-16, IBM PC DOS, ~~7~~ 6 bytes
```
00000000: b041 cd29 ebfc                           .A.)..
```
Unassembled listing:
```
B0 41   MOV  AL, 'A'    ; put 'A' into AL
    PRINT: 
CD 29   INT  29H        ; DOS fast console output char in AL
EB FC   JMP  PRINT      ; loop infinitely
```
[![enter image description here](https://i.stack.imgur.com/ru7xt.png)](https://i.stack.imgur.com/ru7xt.png)
As a bonus, if you run this on your [IBM 5151](https://en.wikipedia.org/wiki/IBM_5151) monitor for a few hours this will actually produce infinite output on that screen until the end of time.
[Answer]
# [Turing Machine Code](http://morphett.info/turing/turing.html), 9 bytes
```
0 * A r 0
```
[Try it online!](http://morphett.info/turing/turing.html?e955f46991325233f2b91f90b5749354)
One of the very few times that Turing Machine Code can compete overall.
[Answer]
# [brainfuck](https://github.com/TryItOnline/brainfuck), 16 bytes
```
+[+[<]>>+<+]>[.]
```
Credit to [the Brainfuck constants page](https://esolangs.org/wiki/Brainfuck_constants) for 65!
[Try it online!](https://tio.run/##SypKzMxLK03O/v9fO1o72ibWzk7bRjvWLlov9v9/AA "brainfuck – Try It Online")
[Answer]
# [Taxi](https://bigzaphod.github.io/Taxi/), 279 bytes
```
Go to Post Office:w 1 l 1 r 1 l.[A]A is waiting at Writer's Depot.A is waiting at Writer's Depot.Go to Writer's Depot:w 1 r 1 l 2 l.Pickup a passenger going to Post Office.Pickup a passenger going to Post Office.Go to Zoom Zoom:n.Go to Post Office:w 3 l 2 r 1 l.Switch to plan A.
```
[Try it online!](https://tio.run/##jY8xC8IwEIX/ytvcAurWrSA4WnAQLA4hpPGw5kJyUv99bJOpIOhwd3D3eN890W/K@cgQRsdJcBoGMraZsMU4V1ym6ttbC0qYNAl5By24RBIbNwkHG1jUj3MFrJeFUfyxmxkdmccrQCPolKx3NsLx4rb@7G9dRV6Zn6U1Xn1LuS/0mvI8kZj7ogmj9mhVzh8 "Taxi – Try It Online")
---
This is an interesting challenge because it requires both refueling infinitely for gas and getting enough passengers to pay for the gas.
If passengers paid enough to pay for the gas used to transport them, the following would be enough:
```
Go to the Post Office: west 1st left, 1st right, 1st left.
[loop]
"A" is waiting at the Writer's Depot.
Go to Go More: west 1st right, 1st left, 1st left, 2nd right.
Go to the Writer's Depot: west 1st right.
Pickup a passenger going to the Post Office.
Go to the Post Office: north 1st right, 2nd right, 1st left.
Switch to plan "loop".
```
However, because passengers do not pay enough this results in [only 54 \* `A`](https://tio.run/##ZZA/C8IwEMX3fIoji4sUdHQTBCdRcHAQh1CvzWFJQnJSv31MWpXYQhLe5c/v3gurF8W4t8BpaISTDQzHpqEaN9BjKlZpdtjwclCeWv2RebMS185adxNyK4EC9IqYTAuKB9rFE6NfBNihs@ny2CetB@tL/oRaqrW5j8ff13PuFFSJE9WPpwMFToWApkUPrc2@5ilL7F94Yz3r0t3PSRn/3BPXOgNcpwzI/BuyEjG@AQ "Taxi – Try It Online"), crashing the program once we are out of fuel.
We can also go to Zoom Zoom to buy fuel, it's way cheaper to buy here allowing us to get [79 \* `A`](https://tio.run/##bY9BC8IwDIXv@xVhFy9joN52EwSPDjwIioeyZVtwNqWNzH8/27nBdEIaXh9Nvj5RL@r7A4P4ahBydgLHqqICM@jQX9b@tFhJMihLdTPKYKbRtWU2tyjexUAOOkVCugYlw7azJUG7crBHw/7xh/PtzjA/yxPY6HLE5FTcnwYUGOUc6hot1BxIy39PmAvzY2gZaLbSTP7/mFtbzqCLmKeOpGjCuGmVhjikjtOo798 "Taxi – Try It Online").
Luckily, picking up two passengers at a time solves this problem of not earning enough per iteration.
The code can be golfed further by removing quotes for strings that don't contain whitespace and minimising the directions.
Ungolfed it looks like this:
```
Go to the Post Office: west 1st left, 1st right, 1st left.
[loop]
"A" is waiting at the Writer's Depot.
"A" is waiting at the Writer's Depot.
Go to the Writer's Depot: west 1st right, 1st left, 2nd left.
Pickup a passenger going to the Post Office.
Pickup another passenger going to the Post Office.
Go to Zoom Zoom: north.
Go to the Post Office: west 3rd left, 2nd right, 1st left.
Switch to plan "loop".
```
## Two 321 byte answers
Before I realised I could go to Zoom Zoom with two passengers I found the following solutions of 321 bytes which have some interesting tricks not used in the shorter solution…
```
Go to Post Office:w 1 l 1 r 1 l.[A]"A"is waiting at Writer's Depot."A"is waiting at Writer's Depot."A"is waiting at Writer's Depot.Go to Writer's Depot:w 1 r 1 l 2 l.[B]Switch to plan C i.Pickup a passenger going to Post Office.Switch to plan B.[C]Go to Go More:s 1 l.Go to Post Office:e 1 l 1 r 1 r 1 l.Switch to plan A.
```
[Try it online!](https://tio.run/##pVC9CoMwEH6VD5dugXZ0UwudSgWHDuIQ5LRHxYTkin371OhS7djh7uD@vh/Rbw7hYiAGpfGCW9dxS@mEI4Y5XKyqzpokS9hj0iw89tCCu2Mhd/A4kzWi/p2vFLbNhcXCAKfIIm@qiaV9xE076BEFWJXcPl8WGlZ7T2NPDr2JGFtFaneaq7poVtA5X42j1C9af72gLy9WP3a/MhXCBw "Taxi – Try It Online")
**or**
```
Go to Post Office:w 1 l 1 r 1 l.[A]"AAA"is waiting at Writer's Depot.Go to Writer's Depot:w 1 r 1 l 2 l.Pickup a passenger going to Chop Suey.Go to Zoom Zoom:n.Go to Chop Suey:w 1 l 3 r.[B]Switch to plan C i.Pickup a passenger going to Post Office.Switch to plan B.[C]Go to Post Office:s 1 r 1 l 2 r 1 l.Switch to plan A.
```
[Try it online!](https://tio.run/##fZBPC4MwDMW/ysPLboVtN2/VwY4TPAwmHopUDXO2tBW3T9/5j@Ec7JAEQt4veXHiSd6fFZxCoqzDpSypkGGPPZohzFhZxvOAcx6QRS/IUVtBOFwNOWl2FieplWMz5Ls5cSYGDgMnoeLeaQhoYa1sK2lQqZE2CONaaaSdfC2gm1KPKYXt0vlMLNcdYVgW5WlPrqjHAd2IFjHo756VS7aRRiyL899f2JWH@R8bHWfevwE "Taxi – Try It Online")
---
Using Go More to get Fuel, even picking up the maximum of three passengers does not give enough money to loop infinitely, so I had to think about it smarter.
If we pick up passengers sooner and take them on a longer route through the city they will pay more for the ride.
Going to Writer's Depot before getting fuel results in [70 \* `A`](https://tio.run/##fY8xC8JADIX3/orQxaUUdHQrCE5ioYODOBw1vQbL5bhLqf/@vGqFVsUhIQnhe@@JulMIewZhKNkLHJuGatzCgHFZx@qwkew5OdLtNI7HPDkXlyQtUiAPgyIho0EJnBwJupWHHVqOXy/48jrjf1Az2JjrxC@pvvUWFFjlPRqNDjSPKkuzb4nYD@yid8@9tDOfP@Kh@hfvK2k1kNTtSLGdMhBD50kIDw "Taxi – Try It Online").
If we pick up three passengers using this route, we can loop infinitely.
Picking up three passengers going to the same destination can be done more byte-efficient than using the same code thrice.
Using `Switch to plan "name" if noone is waiting` we can pick up a single pasenger until all three are picked up.
The quotes around the plan name are optional and it any word after it get's interpreted as `if noone is waiting`.
Using this we get our first 321 byte solution, the code below is the ungolfed version:
```
Go to Post Office: west 1st left, 1st right, 1st left.
[loop]
    [Setup 3 * "A"]
"A" is waiting at Writer's Depot.
"A" is waiting at Writer's Depot.
"A" is waiting at Writer's Depot.
Go to Writer's Depot: west 1st right, 1st left, 2nd left.
    [Pickup 3 * "A"]
[before pickup]
Switch to plan "after pickup" if noone is waiting.
Pickup a passenger going to Post Office.
Switch to plan "before pickup".
[after pickup]
    [Get Gas]
Go to Go More: south 1st left.
    [Print 3 * "A"]
Go to Post Office: east 1st left, 1st right, 1st right, 1st left.
Switch to plan "loop".
```
---
But there's more!
Setting up three different passengers to pick up costs quite a few of bytes.
If we instead split up the string `"AAA"` we can eliminate two lines setting up passengers, at the cost of going past Chop Suey.
With this we don't need to go out of our way to visit the Go More gas station anymore, Fueler Up is on our route and Zoom Zoom is very easily accessible too.
Looking into Fueler Up, it's the most expensive, in fact, it's so expensive that you don't get enough money even taking three passengers!
We can only print [561 \* `A`](https://tio.run/##rZFPa8JAEMXvfopHLl5EqN5yCy3tUUHEg/SwxEl2aNhZdidEP33c@KdVEU89LMw8fvveMKNmz33/JVDBUqJiUVVcUo6OUvOWXkOVTk5V4NpeykGcjraNiP8eZUVRZOCIzrCyq2EUm8BKYRzxQV4Sek64V29CHqwnmLndJWTJ5U/rYeBNjORqCqhlSEl@71Y8Vi0drgG/Qg4nQS3mYXc1n6f2VL72vNnCH@hEbYL@GT/P/NlSk5C1zxGlTUM@3fWTE72gVx1raYcfvjEO2XCobNr3Rw "Taxi – Try It Online"), 187 loops of three passengers, but not infinite as we are trying.
Luckily, Zoom Zoom the cheapest gas station does not require much extra routing at all and taking this route does allows us to enter another infinite loop.
```
Go to Post Office: west 1st left, 1st right, 1st left.
[loop]
    [Setup 3 * "A"]
"AAA" is waiting at Writer's Depot.
Go to Writer's Depot: west 1st right, 1st left, 2nd left.
Pickup a passenger going to Chop Suey.
    [Get gas]
Go to Zoom Zoom: north.
Go to Chop Suey: west 1st left, 3th right.
    [Pickup 3 * "A"]
[before pickup]
Switch to plan "after pickup" if noone is waiting.
Pickup a passenger going to Post Office.
Switch to plan "before pickup".
[after pickup]
    [Print 3 * "A"]
Go to Post Office: south 1st right, 1st left, 2nd right, 1st left.
Switch to plan "loop".
```
It's sad that this does not safe any bytes, but it's the second time I got two answers with the same number of bytes which I think is cool!
(See this [DDoouubbllee  ssppeeaakk](https://codegolf.stackexchange.com/a/195715/89860) challenge.)
I also realised when I was about to publish that *all* strings without whitespace can be written without quotes.
That golved my actual solution a bit more and does not leave the 321 byte solutions the same length anymore.
Even so I still publish this explanation too, because the repeat to pickup three passengers is useful and using Chop Suey was fun :)
[Answer]
# [Bash](https://www.gnu.org/software/bash/) + core utilities, ~~16~~ ~~14~~ 13 bytes
Saved ~~2~~ 3 bytes thanks to [Mitchell Spector](https://codegolf.stackexchange.com/users/59825/mitchell-spector)!!!
```
yes|tr \\ny A
```
[Try it online!](https://tio.run/##S0oszvj/vzK1uKakSCEmJq9SwfH/fwA "Bash – Try It Online")
Also for 13 bytes (written by [Mitchell Spector](https://codegolf.stackexchange.com/users/59825/mitchell-spector)):
# [Bash](https://www.gnu.org/software/bash/), 13 bytes
```
printf A;./$0
```
[Try it online!](https://tio.run/##S0oszvifpqFZ/b@gKDOvJE3B0VpPX8Xgfy1X2n8A "Bash – Try It Online")
Yet another 13 byter, this one written by [pxeger](https://codegolf.stackexchange.com/users/97857/pxeger):
# [Bash](https://www.gnu.org/software/bash/), 13 bytes
```
yes|tr -c A A
```
[Try it online!](https://tio.run/##S0oszvj/vzK1uKakSEE3WcFRwfH/fwA "Bash – Try It Online")
[Answer]
# [Python 3](https://docs.python.org/3/), ~~25~~ 22 bytes
```
while 1:print(end='A')
```
Saved 3 bytes thanks to xnor
[Try it online!](https://tio.run/##K6gsycjPM/7/vzwjMydVwdCqoCgzr0QjNS/FVt1RXfP/fwA "Python 3 – Try It Online")
[Answer]
# [Poetic](https://mcaweb.matc.edu/winslojr/vicom128/final/), 73 bytes
```
why cant i cease,i say
i scream"A"out loud in agony
i cry,as i shouted on
```
[Try it online!](https://mcaweb.matc.edu/winslojr/vicom128/final/tio/index.html?FctBCsAgDAXRfU/xce0lepQ0hiq0CRhFPL21m9k8ZuQJJm0oYCGXWOA0j12uQm84g/WGx3pCUdBt@iPXGcn343mzJJiudVH6AA)
[Answer]
# [AHHH](https://github.com/KyleM73/AHHH), 40 bytes
```
AHHHHhhHHHhHHHhHHHhHHHHhHhhHHHHHHhhhhhhh
```
The right language for the job.
[Try it online!](https://tio.run/##nRlrU9tG8LP1K9ZkMthghGVImjjAtE1ozJTSTpNMZpowjCydrBtkydXDhmb47XT3Tm@dBbZnMPLevm4ft7unqRm5j5YZwxmYruvq1mIBJyewc371YUc7PAT6@2UymcBfYTALzfmc@zO4NP1ZYs4YXPgxCxchw29CnN6P4fd7j8EfQThjfhQz7hP8FmH6vID9PJub3NOtYE6rq9VKJ4wSQrpEq5fcQiAbw8e/LmF5pA8JOGHmknv3wP1owUNmo2R4/@dX6OH/X/nsH3PhBnafMD@7DKI4TKw4CRk4QQgxQnihN6zMCEwvCmAahGGwQmZOGMyJHdH/xpiHAMYgDoDZPD5MInZoc@TJp0nMBoDfsPCYGTGwA383hoh5nrQZSjP9e7BZyJdmzJcMVkF4S2wvHLgPEkBeAnMAZiwZ8sBHpMTDLTGwgsBDucEALiBKFosgYmSVF9y3vMRmJ0tmxUF4VgCi2OaB7pYgFoI8Pq1CQnRiCcIDBDFzjiCbOdxncPXnzce/z88/X1x9/KRp8f2C4QLa0R6PpcwTtOAZzNn8nYZfsJDBIX/MyZP34nk85mhiEwlS6A3ugdMm68sph9K6hiIgZDM0NQuNm6XpJexdBTjKgNqUDFXgumYkl@AUHPQtolQwRioMbRlwG/5NeNwDgc0wHELoaz@0DnegJ372tQ7@7CzQgrHT2zknWPfQ3@m/Qyi7Q1qDHh@0zgvu@GS0iikLyu/@h8Bn@ndJ@oL5NsrIeAwR9pDuit0xq0cBS8EuAplCRGgVrXhsub3aglAQQwyz2cUniwJzOMYngoudNIwNp6cZTJ@ijfxenxjhR5oDuTMQW@zUSQ8OBJj089gSc@UUDAFZudxjvRR4BkPJUOgglHi@Dp0pBuetYCp@r1EhXRUb7O3VkfrEf5hxFFrt70s68cUwBp6kN15VGKSCH6Rds712CznCemS8fq49njlJ6KdebUiRRn7IHTjJHGjkDqzlEW0C0o/UooZAekuQjkEmjFrg/8if5e@Uu75IIvdmalq3IhSVOCUBFf5PoZPRitWH0nPu5nz/kzyAR9n@M/T2nRYBVFOmGs/FgnD/JoorlM2ddZQ7K8122HlpY6YPYK@ucr@V56TI4ONSBveUR12aX1D7dDq9ulSM5ebB2hHBWQEi2rCIcJWJmgRNYeUdqo/orgIs5CoMkhv5ldIgo6cNUv@0mmekMs@oYZ51vBs2U32abNuMuJ5aadKR2qRlmxZZ9jq3ad2x@2qlOutcShm2xoVFnvzUEDd6trjR88RNSkXwjeoMUXi/dIAX@Ws9mb0VX1cFqVNwxrB6m6HiyExrZ45AKu1@93erAtvOzkmpdrzNzdxUI62BTfIiKIxhC31aAhX0RelKa1fjYKK9YffsOCz8ZgyH13UzUE9hySRrLki6m4j/R/6nf4HTk8D@QaUDseCkgl2vCaojM9XKul7vJololeuvmn7YRFBQUCxmVAfGNdUy6XFl4ucWrwLLB5HW5G8R16qpFPyfF34KEcogx@aeZzsjeq11G3n8lCqfMWqJv/wMbkRgqVQYR20c9k5h9K5IVsmIerWHTsaqlAzHT7Daa8w5SuVK6VEtZKotyvOopWurdd@KVZx1l6pUajTTGM9oCTqozaWYeaNbvoCFGcXgsztMyGA@N30bVi7zwQuCW7oPoLFarNLMoTfkO@0TR70tLZEqo1w1WtQwVDndSW2w1xw1lcgNu2gqvG03l5Ln9XgN67ZBZB3LfLhRLCobknZZaF6KWfK1cDT5OAsDXcXrR7tm5T66jiCtSW5q2eOT3Kglo3GrDlMFZmVmUzBaNzC0Dy5uN0/v181hAEeBdJquUNrMMRMvJvxUrLiZSGdC@tLWxGU@Vso@6EHencxNnIHEzYEZzqwB0GG@t0c/ltmtRk8sYYEcQfVmg5T8EpkzNoaXkeCk0/Xgd1@MMcTi2/AailsPMEDee2id3y4uz/fAoYuVYMH8nsQ2rgewE07FxqVkh5x89eXysiH6ven7QQxEDVGQhBYDBzMevr2MrvVCAeO67JK6GuXu4jjtLWiki1ic1aMBDAdwjBRo2PR@yLTpPMvvhGQPEiR0XSiPT8knPYG6DpVSJ8vvUuQLQgcJ7eqpm3UGR9QZOFRhyRDluihTMSPtRnHoW/MFWoXuCXcGueqod3pBUmidtcGaTHSQk5Fc7VeqjII/5XWTv/pYLF0QUOLU22BokTHZRoaxkYzJVvsYbSZjq30cbSJjsp0/jjeTsdU@Xm0kYzt/vN5Mxlb7@GkDGZMt8@PNZjK22sfbjWRs5w9juJmQ7RLdSCtjO/ctU8MYPZP7drofPY/7luY/fib37XR/9Rzu1NgoS5CS5eviNjvnmtXSMyJWNEaf7v3YvAPxXmWcNdEwT3D8EHe6sOKxC7tUC3dFM5KpXar@uURaSAXKew5NVj@5s9JEVR@o1rQJ5TE1f6xe@9Q5peV@SOU@u@poXHTkCwXSaB3SqIR0hEidyupR7cIhVVQ0RI7lBRHL2g3166mSJ8jE@adLtj6/Y1YSUy8hGjFdL3eDshmT77FkM4ONMPe5bEOze3mx0HjHULQQa18tpBf6aZ/UHLjqr44ku7RNa6B3189nFB/dtW9narlUHt5qHbuWteRD6sfPrz5omnzLTkxFL02v2RH@KAxNRdKVtnbFs@s@CqLZ/j4cfDU9r3g9fxCId8aafiheMucMH4f/Aw "Bash – Try It Online")
### Explanation
```
AHHH  Start program
HhhH  Increment cell to 1
HHhH  Double cell to 2
HHhH  Double cell to 4
HHhH  Double cell to 8
HHHh  Square cell to 64
HhhH  Increment cell to 65
HHHH  Loop while cell is nonzero:
Hhhh    Output cell as ASCII character
hhhh  End loop
```
[Answer]
# [Vim](https://github.com/DJMcMayhem/V), ~~14~~ ~~7~~ 10 bytes
```
qqiA^[@qq@q
```
Added 3 bytes to fx a bug kindly pointed out by [David](https://codegolf.stackexchange.com/users/52622/david-ljung-madison-stellar).
If you fire up `vim` (with no command line options) and type in these key strokes (`^[` is the esc key) then the screen will fill up with `A`'s.
Explanation:
```
qqiA^[@qq@q
qq          Start recording macro-q
  i         Enter insert mode
   A        Insert A
    ^[      Exit insert mode
      @q    Call macro-q from within macro-q
        q   Stop recording macro-q
         @q Call macro-q
```
### Note: You'll probably have to `kill` that session of `vim` to stop it!
You can try to stopping the macro with ctrl-c, if that works you can exit with `:q!<Enter>`.
[Answer]
## Apple II 6502 Assembly code, 7 bytes
```
L1: A9 C1      LDA #'A'
    20 ED FD   JSR COUT
    50 F9      BVC L1
```
[Answer]
# [Piet](https://www.dangermouse.net/esoteric/piet.html) + [ascii-piet](https://github.com/dloscutoff/ascii-piet), 12 bytes (2×6=12 codels)
```
ttttlIauqasj
```
[Try Piet online!](https://piet.bubbler.one/#eJwliUEKgCAURO8y6xGUSsKriIuwHwhWgrWK7t6HZhZvHvMgn6sgxGj519PZxOg8J45UDJxTIro0BBhjQNSy63ZWoyY9I2xL7UKUo92Xfng_8LwXAw)
In grid form:
```
ttttli
auqasj
```
Represents the following Piet program:
![](https://raw.githubusercontent.com/Bubbler-4/svg-stuff-and-tools/cc815c7cc08e68b661d1dfd1c8747993e7eb3ec6/images/CodeGolfSE/200306.svg)
### How it works
![](https://github.com/Bubbler-4/svg-stuff-and-tools/raw/313ff4bdc5abac91e2312359b2fb864513ce697c/images/CodeGolfSE/200306-e.svg)
```
pointer      command    stack
t<4> -> l    Push 4     [4]
l -> i       Dup        [4, 4]
i -> j       Dup        [4, 4, 4]
j -> s       *          [4, 16]
s -> a       *          [64]
a -> q       Push 1     [64, 1]
q -> u       +          [65]
u -> a       OutC       [] Print 'A'
a -> t       %          [] Stack underflow; ignored
```
[Answer]
# [C (gcc)](https://gcc.gnu.org/), 20 bytes
```
A(){A(putchar(65));}
```
*-4 bytes thanks to [ceilingcat](https://codegolf.stackexchange.com/users/52904/ceilingcat)!*
How could I have forgotten recursion...
[Try it online!](https://tio.run/##S9ZNT07@/99RQ7PaUaOgtCQ5I7FIw8xUU9O69n9mXolCbmJmnkZZfmaKJlc1lwIQAFVac9X@BwA "C (gcc) – Try It Online")
[Answer]
# [Hexagony](https://github.com/m-ender/hexagony), 3 bytes
```
A.;
```
[Try it online!](https://tio.run/##y0itSEzPz6v8/99Rz/r/fwA "Hexagony – Try It Online")
```
 A .
; . .
 . .
```
`A` sets the value of the current memory edge to A (ASCII 65).
`.` is a no-op that places the next command on a new row.
`;` prints the value of the current memory edge to `stdout`.
---
The no-op is required because the instruction pointer never returns to the top row after executing `A`.
It only loops over the second and third rows.
[Answer]
# [APL (Dyalog Extended)](https://github.com/abrudz/dyalog-apl-extended), ~~11 9~~ 7 bytes
```
⍞←⍣≠'A'
```
[Try it online!](https://tio.run/##SyzI0U2pTMzJT9dNrShJzUtJTfn//1HvvEdtEx71Ln7UuUDdUf3/fwA "APL (Dyalog Extended) – Try It Online")
-2 bytes from Bubbler.
-2 bytes from Adàm using forbidden hacky APL magic.
Older answer:
```
{⍞←'A'⋄∇⍵}0
```
### Explanation
```
{⍞←'A'⋄∇⍵}0
      ⋄     separator (arguments will be evaluated left to right)
 ⍞←'A'      Print 'A' without newline
       ∇⍵   Call function again with the same right argument
{        }0 Call first time with 0(any number works)
```
[Try it online!](https://tio.run/##SyzI0U2pTMzJT9dNrShJzUtJTfn/v/pR77xHbRPUHdUfdbc86mh/1Lu11uB/GlDoUW/fo67mR71rHvVuObTe@FHbxEd9U4ODnIFkiIdn8H8A "APL (Dyalog Extended) – Try It Online")
[Answer]
# [Malbolge](https://github.com/TryItOnline/malbolge), ~~2163 2069 1881 1787~~ 1693 bytes
```
b'a;$9"~}HG{iyxwuu?O=pL:]mHj5!3DCezRQ=+^:('&Y$#m!1So.QOO=v('98$65a!}^{@hyf<WV9sr%4#I20FEJVBfw)btOr@#!7~|4{y1xv.us+rp(om%lj"ig}fd"cx``uz]rwvYnslkTonPfOjiKgJeG]\EC_X]@[Z<R;VU7S6QP2N1LK-I,GF(D'BA#?>7~;:9y16w43s10)p-,l*#(i&%e#d!~``{tyxZpuXsrTTongOkdMhg`Hd]ba`_^W@[ZYXW9UNSRQPOHMLKJ-++FE''<A$?>=<;:387xw43s10/(-&m*)('&}${d!~}|^zyxwvutmVqpiRQlkjiKafedc\E`_^@\[ZYX;V9NMRQ42NGLK.IH*F?DCBA$#>7~;{{8xx5uu2rr/oo,ll)ii&f|e"!aw`{z\r[vXnmVTpongPkNihgJ_dcFa`B^]\UZ=RWV8TSLQ4ON0LE.IHA)E>'BA:?!7~5|38y6/v321q).-&m*)i'&%|{d!~}_{zs\wvutsUqTonPlOjiKgJedFbE`_A]@[Z<X;VU7S6QP22GL/JIB+FEDC%;@?>7~;:987w5v32r0)p-,+k)('~g$#"b~w|uz]xwvutsrqTinQlOjLhgfeH]bE`CB]\>ZSXWVUTSRQPON1LE.I,+*((&&$$""~~||zzxxv4u210/(-n+l)(i&g$ddy~}`u^]\ZZotsrTjShQOOMMKgfeG]F[DB^]?[T=R;9UTS5K4I200..,,*F)DC&A:#>=~;|9yyx/vutrrp.-,l$k"i~ge#"!aw`u^\\ZZXXVrqpRhQfOMMKKIeHcbECC^W\?>=;W:UT7R5PIN1L/.,,*FED&<%:#!!}}{987w/v-trrppnnllj(i&%ee"!xa|_^\x[vutWrqjSnQPNNLLJJHHFFDDB^A\[==XWVOT7R542N1LKJ-HGF?D'B%$""~<;:z2y0wu321q)p'nl*)(h~g|eccaa__]][[YuXsrTTonmleNiLgfeG]F[`C^]\?ZYXWP9T76442NML.D-B+)EDC%;$9"~<;:z2y0wuussqqoommk)j'&ff#"!~}v{^y\wvXtmVkpSnmlOjihgf_dGbEDBB@\?==R;PUTS5K4I200..,,**(DCB$:#8!}}{{yyw5v321r/.-,+*#j'h%$#cybw`^^s\ZvuWslUjSQQOOMMKgJedc\E`_B]@[==<QV9T76KPON0F/D-++))'CBA#9"7~||z87w5.u,sqqoommkki'h%$#d!xa`{^\\qZotsUqjShmPkjMhKfe^cFEDYB@@>>S<:VU7SL5J311//--++))'C&A@#>!<;49z76w4u2rr).-n%lkjhhffddb~}|^t]rwZXXmrUpoRmfONihgI_H]FD`_^@V?T=;;9977553311/K.IH+))>C&%@?>~6}49z76w4u,1rq.o,+l)j'~g$#d!b}__^yr[ZuXsrUSSnmfkjiLKfedFbaDY^A\[>Y<WVOTSRQ43H1FKJI+A*?(&BA@"8!6}{987w/v-trrppn,mkk"'&%e{dyb``^^\\ZZXXW22}Rn-O>Nvu(IeH6F[`~1A@hZSRuc9rrqK4\lMkK-CHAS(ubBN:L!J6}kXW1wfv3Prr`;o,%IH(4~}|d/@Q>v{;(\wZ$W4V1}/R-PxjvuKf_$G#nZ}B|z>-xwQc88qR^nO1GL|JVyGeEca&$$?8[6|GjWxg/AR2POq(o,JH6j4&C$0@@-a`^:y[q6H54rq0BR--N*chJ&_%cF!CY}Ai.-wwWV(s6%4o\lZkKDz,fdRQ
```
[Try it online!](https://tio.run/##PZTnmvEMEIb/f2cRgqghWrBaEKKL3oVEjRZSiDj1/SZ23z2B@3rmnmfmyInLs7gRvr@XDi6Bxixvo1TUdw9NleV0I3mpxqfH0j6MBPM54cm2ku5ZHHPYh6j1iATaZ1@r0UgqmCNGopEwhxgzPbN9rL/6vdhNsoWsDOGnC@UetVady3tDyliR6PsV0h8BTfHJN7d0wc5Hm7i37DbGmrestMVCfk4lVRmebuKhcz411439rrIpC8XppJCbD6aZ8eiLTfS60Xak1STqgWrFy3iKNJZ3UFlrOhV9J@KxRyCihoK3gN958XpElxXb2W2ClUfei4V@f2ijizy4SR2gbxoHvrbdLEr8dMkt5rM@0IeDfqxbb7OtZqNUq1bKXrebLjgcX1k0nUp@JeJBMqr90HHMaz@6nCDDQHWgG6/ZE6wp8v3Yu152bEs8QHZuLfCrSQHomYlJT/Ri9RrbChH1YrXiY0ouOp3PUVnUambXdVLTwrJMSBJ@PntE0bnb2dcvwYJw6kJ/TqSxMjgde50LZG8e6rvtpjznVzS3oGbTSXeUZPs9stOutkKNur9aAHrWWUiBmXgavIdfQfIRwZUgEbg6fZ/sO4fd9vpkn@vP28TMfuteTe/ir3eeXkL27Mf74M87UaziZYYCM/mcLZH59U5G1TDQpY939wHMvDeo1bJ8qy/Y6sfMTbp2dqcW0KvbzVooTYGeo6aT1Kg96Pe6nY932Cpk97hdGGa3o6jF8n6/Xs@npikhmfh4P7lFJ2x1g/L8420sZJh@NBoMetL1wm5b60atVqkwQommx6b3XrozNBvZqUH2INB9Pi/ldjkdDpvNakUQw9D1x0MNw1bdkvNyOomw1e178xJWyNJ4zadT7apALz5mzOyrbWXNAD3/S08mErFYFLIHGaLo9/k8HpeZnbJl0gjylQjp5OM3@9X0Lh5M74LOP5aLxWw2@cne63RY9uO9Wi6bneHyuVk2/S97FMww9YC/AvQs7cznwIzZyPAL6KrqC95N@hmsOS1gZq1bVhynzM2@K@fBUepezOzQyC23ZvgiPc4P/@hd8rfvfuh7yU1jGHQGtpqMGC9zq7jivUt@/AzZ0cNut9kIwgroczAzVkfyvd816TCXaabMFM1GQvZP3/u9RicaCQeDgQCO5xkwkzZvFU2TyJcBndH8KnyC2/V6/tzqHtmu4RPArUL26Xg8HPZ/vB@bAvQdvPOfrVJwq6lkArJHa5FKiCD8H@9g5t@tRoy4TkYj8Gc8tyvu88Kfse63Jp1f/njXxorc74tAZyF7bVU1zayWhdGcyk7SIzAT79bBe6hB1HDcB313FbAcBZ0Butn3RyQsB4mbCzf7Do1E7DZU@KOrcKt9sbtvt@BH1uBWmXlpSufzFJXJpEbQmWaMvLJn63Fcq@7LvUe2zcv2L/RqIcvQyCehqaoQXDU4/HzykAcreM91BctjycGKwTuDhvoSkWPZZ/pQd23vMfssch4fc5S@gzeUUO6kIxKGPzMe@X1bxq0JiuPeQGfW8/idGA5IbaOGWqsAd/FVTm7GStN2IyfgLMclXbW4pEbR8FEiDPbkbaTqiozBNUXA@zuQzWxHbVZexSTpWglNxNqh4s2Vsm1MXlL1eBUpR4zDoB9Q10qwKUmLxNlTLpWwEHxHHs@0UoqewCbqCO2HegEDZ71Nba9sy/Y5uqKRkUG9nimvprZWJJiZnRqBYvUFZooC2/rv@/t/ "Malbolge – Try It Online")
-94 bytes thanks to @user100411.
This was built with [Prof. Masahiko Sakai](https://www.trs.cm.is.nagoya-u.ac.jp/%7Esakai/index.html.en)'s [LAL](https://www.trs.cm.is.nagoya-u.ac.jp/projects/Malbolge/lal/lal-def.html.en) toolchain from the following source code.
```
PROGRAM_START_TO ENTRY@Argh
ROUTINE Argh {
ENTRY:
ROT A
A: 0000021020t
REV JMP
REV_JMP:REV JMP
OUTPUT
DUP
JMP REV_JMP
}
```
[Online LAL assembler](https://www.trs.cm.is.nagoya-u.ac.jp/projects/Malbolge/lal/on-lal.html.en)
[Answer]
# [><>](https://esolangs.org/wiki/Fish), 4 bytes
```
'A'o
```
[Try it online!](https://tio.run/##S8sszvj/X91RPf//fwA "><> – Try It Online")
### How it works
The instruction pointer begins at left, and its initial direction is to the right.
`'` starts string parsing mode. Everything until the next `'` will be interpreted as individual characters, that will get pushed onto the stack. So `A` pushes that character, and then the second `'` ends string parsing mode.
`o` pops the character from the stack and outputs it to STDOUT.
The instruction pointer has now reached the end of the code, so it wraps around to the initial position and keeps moving to the right, causing an infinite loop.
[Answer]
# [Burlesque](https://github.com/FMNSSun/Burlesque), 3 bytes
```
@'A
```
[Try it online!](https://tio.run/##SyotykktLixN/f/fQd3x/38A "Burlesque – Try It Online")
`@` is an odd operator. 
* For integers, it converts to double (`@1 => 1.0`)
* For two letters, it pushes both to the stack individually (`@az => 'a, 'z`)
* For characters it prints the character infinitely as a string (`@'a => "aaaaaaaaaa...."`)
* For anything else, it does nothing and just remains on the stack (`@1.0 => @, 1.0`).
```
@   # A symbol which does odd things. For a char, it repeats infinitely.
'A  # Literal A
```
[Answer]
# [Unreadable](https://esolangs.org/wiki/Unreadable), 208 bytes
> 
> '"""""'"""'"'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'""'"""
> 
> 
> 
[Try it online!](https://tio.run/##K80rSk1MSUzKSf3/X10JBNTBWF1pyCOl//8B "Unreadable – Try It Online")
Explanation (`A` has codepoint 65):
```
'"""""'""" while(1≠0)
'"         print unicode character number
'"" (×64)  1+1+1+… (64 times)
'"""       1
```
[Answer]
# [Piet](https://esolangs.org/wiki/Piet), 30 26 Codels
It's a .png 13x2 codels, a few are technically not used (4 white unused, 1 white as transition and 1 black to change direction). But since I don't know how to compress it further, I still count them.
Original file (codel size 1): 
![Codel Size 1](https://i.ibb.co/ySwXs1P/v2-cs1.png)
With codel size 10:
![Codel Size 10](https://i.ibb.co/QDs6cFz/v2-cs10.png)
For some reason, the codel size 10 looks disproportional. Maybe it's an issue with the [IDE](https://gabriellesc.github.io/piet/) 
Pseudo code (incl. stack):
```
push 2    | Stack: 2
push 4    | Stack: 2, 4
push 2    | Stack: 2, 4, 2
push 4    | Stack: 2, 4, 2, 4
*         | Stack: 2, 4, 8
*         | Stack: 2, 32
*         | Stack: 64
push 1    | Stack: 64, 1
+         | Stack: 65
dup       | Stack: 65, 65
out(char) | Stack: 65 | Output: A
```
dup and out(char) are repeated indefinitely.
[Try it online!](https://tio.run/##bZK9SgQxFIV7n@IUYqNFfuenEZJJVrdQRHQVbGwsxMbCQixEwdZCfQMFRdGFbWxkEZIH8hHG3JlVdwfD5UxIMl/OvTfHhwcndc06A0UJzaA8VA7mwAy4IU1bk3BQJVQBpaAFvj7HG@srSX8DoMX@qtucm2VzNkP5mwuwAiz7WykkrIPO0LJanaaH8aADFwymnGGSSwXFoRXyxOfwFSWTezhBZ8LzxKozW6fpG1@TnMfbDln@MOUsUzlUnCLlUqVd1mShaAIIgq7Fy3hJ4AvWmmcdtEq/SfCyCQeRwVpKW2vwHiyHsKgUMgvH6aT0kL@VWAgfg22qxWgxXh3FG7ncoac@@hy6QK5IvYSo4CQqByOgm/72ONHLnK4xDvFp92Q3PizFu3gd7nfI@@iI9Cq8dehZKriBUGRTW3CPMtVEgGuqVW5gPHyG3lRbw8t8GO217i318iwM42N875Dz5jCVWjcPUREqkdONhcD/o@/XXRja/USt628 "Piet – Try It Online")
This is my first submission here and my first "real" program in Piet. I'm sure it still has some room for improvement, but I just wanted to share (what I think of as) a lovely language :D 
Edit:
Compressed down from 15x2 to 13x2.
[Answer]
# x86-16 machine code (DOS 1+), 8 bytes
Disassembled listing (`objdump -D -bbinary -mi8086 scream.com`):
```
   0:   b4 02                   mov    $0x2,%ah
   2:   b2 41                   mov    $0x41,%dl
   4:   cd 21                   int    $0x21
   6:   eb f8                   jmp    0x0
```
Output (DOSBox 0.74, and a lot faster than it looks):
[![](https://i.stack.imgur.com/fVY6H.png)](https://i.stack.imgur.com/fVY6H.png)
Here's my ldscript and command-line options for anyone interested:
```
OUTPUT_ARCH(i8086)
SECTIONS {
        . = 0;
}
ENTRY(_start)
OUTPUT_FORMAT(binary)
```
commands:
```
as --32 scream.s -o scream.o
ld scream.o -Tldscript.lds -o scream.com
dosbox ./scream.com
```
and unmolested `scream.s` file:
```
_start:
    mov $0x02, %ah
    mov $0x41, %dl
    int $0x21
    jmp _start
```
[Answer]
# [Common Lisp](http://www.clisp.org/), 15 bytes
```
(loop(princ'a))
```
[Try it online!](https://tio.run/##S87JLC74/18jJz@/QKOgKDMvWT1RU/P/fwA "Common Lisp – Try It Online")
[Answer]
# [Clojure](https://clojure.org/), 16 bytes
Another Clojure version saving 2 bytes over previous solution, posted as a separate answer because I don't have comment rights yet.
```
(while 1(pr 'A))
```
[Try it online!](https://tio.run/##S87JzyotSv3/X6M8IzMnVcFQo6BIQd1RU/P/fwA "Clojure – Try It Online")
[Answer]
## [Lua](https://www.lua.org/), 22 bytes
```
::a::io.write"A"goto a
```
[Answer]
# [Pyramid Scheme](https://github.com/ConorOBrien-Foxx/Pyramid-Scheme), ~~111~~ 98 bytes
```
     ^
    / \
   /do \
  ^-----^
 /1\   / \
 ---  /out\
     ^-----
    / \
   /chr\
  ^-----
 / \
/65 \
-----
```
[Try it online!](https://tio.run/##K6gsSszNTNEtTs5IzU39/18BBOK4QKS@QgyI1k/JBzPidEEAKKVvGAOTBQoAWfmlJWCVMDUoupMzihC6ucDC@mamQBIs8P@/MZcJlykA "Pyramid Scheme – Try It Online")
# Edit:
98 bytes thanks to @Jo King and height-0 pyramids. Also, `chr 65` is truthy.
```
   ^
  / \
 /do \
^-----^
-^   / \
 -^ /out\
  -^-----
  / \
 /chr\
^-----
-^
 -^
 / \
/65 \
-----
```
[Try it online!](https://tio.run/##K6gsSszNTNEtTs5IzU39/19BQSGOS0FBXyGGS0E/JR9IxemCQByXbpwCVBzI0s8vLQGygEywLFxHckYRTAdQA0gpF1hG38wUSILF//835jLhMgUA "Pyramid Scheme – Try It Online")
[Answer]
## [NDBall](https://esolangs.org/wiki/NDBall), 52 bytes, 7 instructions in 2 dimensions
```
(0)>0
(1)+
(2)Y[65,>1,>0]
(3)p
(4)<0
(2,1)<0
(0,1)<1
```
[![Program](https://i.stack.imgur.com/dg2iy.png)](https://i.stack.imgur.com/dg2iy.png)
In essence, this just loops the ball on an add 1 loop until it reaches 65, then it bounces back and forth over p repeatedly printing "A"
[Answer]
# [Bitcycle](https://esolangs.org/wiki/BitCycle), ~~25~~ ~~16~~ 14 bytes
```
~1000~!
>0010^
```
[Try it online!](https://dloscutoff.github.io/Esolangs/BitCycle/?p=z103zbre0210n)
Output as a stream of bits. -9 thanks to DLosc. -2 thanks to JoKing.
[Answer]
# [Java (JDK)](http://jdk.java.net/), ~~85~~ ~~77~~ 34 bytes
```
v->{for(;;)System.out.print("A");}
```
[Try it online!](https://tio.run/##LY1BCsMgEEX3OcWQlS7iBaSFHqDZBLopXUyNFlOjIRqhBM9utc1mhvnM@2/CiN00vrMw6D1cUdu9AdA2yFWhkNDXEyA6PYIit7oi5SVLTRk@YNACerBwyrE778qthHM6fHyQM3NbYMtaykh7aSlPmVdo2Z6mQAf7a56LlwyhvL7uD6R/p2WK2M2YQ5fyFw "Java (JDK) – Try It Online")
Massive thanks to @Kevin for the lambda solution. I really need to learn how to do that. 
## Old Answer
```
class M{public static void main(String[]args){for(;;)System.out.print("A");}}
```
[Try it online!](https://tio.run/##y0osS9TNSsn@/z85J7G4WMG3uqA0KSczWaG4JLEESJXlZ6Yo5CZm5mkElxRl5qVHxyYWpRdrVqflF2lYW2sGVxaXpObq5ZeW6BUApUs0lByVNK1ra///BwA "Java (JDK) – Try It Online")
It's a full program and can probably be golfed if I knew how lambdas work in java. Oh well. 
[Answer]
# [Perl 5](https://www.perl.org/), 15 bytes
```
print'A'while 1
```
[Try it online!](https://tio.run/##K0gtyjH9/7@gKDOvRN1RvTwjMydVwfD/fwA "Perl 5 – Try It Online")
[Answer]
# [International Phonetic Esoteric Language](https://esolangs.org/wiki/International_Phonetic_Esoteric_Language), 9 bytes
Derived from my answer to ["Shortest code to produce infinite output"](https://codegolf.stackexchange.com/questions/13152/shortest-code-to-produce-infinite-output/206214#206214).
```
"A"10ɑbuɒ
```
## Explanation:
This works because the `ɒ` instruction don't do anything with the loop index except to check if `index < limit`. If it is, it loops back to its associated `ɑ`. Otherwise it exits the loop (index manipulation is handled with `e` adn `ø`).
```
"A"10ɑbuɒ
"A"       (Push "A")
   10     (Loop bounds: 0 to 1)
     ɑ    (Start loop)
      b   (Copy top)
       u  (Print with no trailing)
        ɒ (End loop)
```
[Answer]
# [Alice](https://github.com/m-ender/alice), ~~4~~ 3 bytes
It's a pretty simple Cardinal mode answer.
-1 bytes thanks to Martin Ender
```
'AO
```
[Try it online!](https://tio.run/##S8zJTE79/1/d0f//fwA)
## Explanation
```
'A  - Push "A"
  O - Output as character
    - The IP wraps around to the left, and repeats.
```
]