If it was possible to intercept and send the machine-code being sent to the CPU, to a cassette/disk.
This sounds like you want to record the instructions a CPU is executing to some media. If yes, than this is way beyond any capability of a home or personal computer, as the data rate is simply beyond what any storage system could do.
- A 6502 running at 1 MHz, like on a C64 would need to store about 1 MiB/s.
- That's about 2000 times faster than the fastest cassette interface could deliver (average home computers were even 2-5 times slower).
- It's as well some 250 faster than a floppy system of that time (not counting seek times)
- Finally it's still 2 times faster than the maximum transfer speed a ST506 or ST225 hard disk could deliver.
So no, simply not possible to intercept any code send to the CPU
Not to mention the extra hardware needed to capture and record this date - after all, the process is usually done in software. Heck, it's still the same today. Modern CPU again run faster than any regular storage media can record.
Doing such recording is the domain of In Circuit Emulators. And even these usually operate by stopping and/or and slowing down their target. Quite expensive devices. A somewhat capable system for an 8 bit home computer in the early 1980s was in the region of 20,000 to 50,000 USD, depending on capabilities. Systems capable doing real time ICE for modern CPUs go easy past 1.5 million USD per unit.
So, no. Not even close to the capabilities of an 8 bit system at the time, nor within price range of a home system.
If it was possible to intercept and send the assembly-code ( generated after the BASIC was converted to assembly-code ) before it was converted to machine-code, to a cassette/disk.
Not really sure here either. For one this sounds like simply saving the program. No need to 'intercept' anything, just save it to media, the very same way like it's done today.
Except that BASIC does not generate any Assembly code. BASIC is an interpreter language, essentially a virtual CPU, like a Java byte code interpreter.
I'm wondering if maybe home-computer manufacturers didn't include instructions to save BASIC-Language programs as assembly-code or machine-code in order to monopolize the software/games market for their machines, since I assume that assembly-code or machine-code run alot faster than BASIC-Language software.
There are several misconceptions here:
Save and load for BASIC programs are integral to the BASIC language. After all, what good is a programming language when programs can not be stored and retrieved?
All BASIC machines (*1) at the time used BASIC, as mentioned, Interpreters. There is no machine code produced.
Even less any intermediate Assembly source. These machines simply had not enough storage (RAM, floppies) to compile in a two stage process. Compiler for home computers, if available at all, always produced direct machine code.
Such compilers were almost always (*2) third party software - which then of course could save their product - who would spend money on a compiler if it can't save the produced code? Or, would want to spend much time waiting for compile before running any program?
While machine code is of course faster than BASIC, this is not always needed, not even for games.
In fact, several home computers had their BASIC especially improved to handle performance relevant parts like sound and graphics with additional commands, allowing write fast paced games in BASIC (*3).
Last but not least:
What was true for game consoles - that console manufacturers wanted to make a share from games sold (as well) - was never the case about home computers. They are an open architecture by definition.
So, why should computer companies artificial cut down machine features? Their intention was to sell machines, wasn't it? Crippled designed do not really sell well, do they? Even less if other manufacturer machines do provide these features?
*1 - That is home computer class with BASIC in ROM at the time
*2 - Trying to be careful, with the incredible number of different home computers that were designed and sold at the time, there might be some odd one who had a compiler included. Never say never when it's about Punk-Age-Computing :))
*3 - Not just Woz' Integer BASIC which was intended for Games i nthe first place, but as well machines like the TI 99/4. This computer was often looked down at for being ... lets say "not fast", but with extended BASIC, it was possible to create and animate graphics while playing music of typical games of the time without a single line of machine code.
P.S.: Considering various more or less well worded questions over the last days, it seems you're trying to research a certain use case, but miss the needed basic concepts about computers in general and simple (1980s) computers in particular to ask the right way. It might be useful to point out the purpose of our search and how the information gathered is to be used, so we can tailor answers more to the point of your search.