The OSI machines were not so much 'cloned PETs' as 'reverse-engineered PETs'. The BASICs were practically identical. The memory and CPU were the same. The character sets were as similar as copyrights allowed. It was blatantly obvious that Ohio Scientific's purpose was to ride the coattails of the PET.
Though it used the same CPU, an Apple was a totally different beast. Its architecture, OS, and BASIC were hugely different than the PET's.
Suffice it to say that my OSI experience transferred directly to the Commodore 64, while my friend with the Apple never could grasp the way my C64 did things.
Yes, the CPU's were the same. The 6502 DEFINED low-cost 8-bit computing. The BASIC's were the same because all three companies (Commodore, OSI, and yes, even Apple) all licensed the SAME version from Microsoft. However, saying the OSI was even remotely reverse-engineered from the PET is incorrect. I know alot about the OSI's and I see NO resemblence in architecture between the two machines. Yes, the OSI had nice "graphics" in the character set, but so did Atari. The OSI used ASCII, while the PET used a proprietary "PETSCII" character set. Hardly "as similar as copyrights allowed"... The OSI's were built almost entirely of standard TTL chips, where the PET used in-house MOS chips for everything.
The OSI kernal is entirely different, the BASIC ROM and screen are at different locations. The keyboard is different. The screen is 32x32. All the ports are different. It has a CPU-driven floppy interface option (like the Apple) and even a hard drive board. How is that the same?
Did you know the OSI had a 6502 "trainer" board in 1976 and a TRIPLE CPU (6502, 6800, Z80) card in 1978?http://osi.marks-lab.com/boards/boards.html
Here's a discussion about Microsoft BASIC:http://www.pagetable.com/?p=46
And you can check out my home page for info on the OSI C4P...http://email@example.com/OSI/index.html
I will say, the OSI also gave me a lot of experience too when I moved to the C64.