I hear social media video blogger repeat over and over that there was not a keyboard standard in the 70s and 80s for home computers. This unfortunately is true - kinda. There were really
two loose standards. How do I know? First, I own quite a few computers from the 80s. It was IBM PC that broke the simi-standard and then redefined the overall standard by "winning" the PC wars.
So what was the standard layout before IBM changed it all?
First there is What I call
Standard I - This was used by majority of the early 70-80s home computers
1) QWERTY keyboard like most type-writters
2) Specific characters associated with SHIFT and numbers

(Photo of a Commodore 64 keyboard)

(Photo of a Tandy CoCo 2 keyboard)

(Photo of an Atari 130XE keyboard)
Above the 1=!, 2=", 3=#, 4=$, 5=%, 6=&, 7=', 8=(, 9=)
Who adhered to this Standard I:
- Amstrad
- Apple I and II
- Atari (400, 800, 800XL, 130XE, ect) - *Mostly*
- Commodore (PET, Vic 20, C64)
- Dragon (32 and 64 computers)
- Tandy (Model 1, Model 2, Model 3, Model 4, Coco, CoCo2, CoCo3 and others)
Probably others were included.
Anyone that does retro programming on these systems knows it is an adjustment finding the quote above the '2' key.
Atari put a '@' with the 8 and shifted the '(' and ')' over one place.
Where did these companies come up with this format. Many decades of typewriters before them. This was much of their layout.

Standard II
Who did not use Standard I, but the Standard II?
- Later Apple computers and Macintosh.
- Later Atari computers (ST line),
- Later Commodores (Amiga line),
- all IBM computers and most compatibles like Tandy 1000 line.
- Coleco Adam
- All Texas Instrument computers.
IBM came up with this design, which may have influenced later keyboard's such as the Apple IIe's/Macintosh, the Commodore Amigas and Atari STs.
With the Apple IIe, Apple changed some keys around like the 2 key to be associated with @ like the IBM.

Texas Instruments TI-99/4A keyboard
What is the Standard II number line layout?
1=!, 2=@, 3=#, 4=$, 5=%, 6=^, 7=, 8=*, 9=(, 0=)
Somehow people were swayed into believing the IBM PC was superior to the computers of the late 80s. Really was not true, but perception often wins. As PC clones became the norm, so did this keyboard layout.