How to do machine ROM dumps?

Some Eeprom programmers can auto-detect the type of ROM.
Or just select the largest type and see how much "blank" space is in the file.

That is the first thing I did, using my trusty MiniPro TL866CS, I tested both for a blank check and tried to read it, and the programmer couldn't identify it nor read anything of it.
@NYYRIKKI it was easy to find Japanese or western machines with ROM dumps, sadly Arabic machines are pretty neglected and obscure in this regard...
also, I can't use the floppy drive because this specific machine is faulty with no video out and no floppy, an AX-350II am working on, however, I may do that on my AX-370.
so far, I have a ROM dump of AX-200M that has the standard AM27256 in a .HEX file format that I will be uploading tonight hopefully

Imho the only reliable way to dump ROMs is remove them from a machine, place in a dedicated reader (such as an EPROM programmer, purpose-built cartridge etc), and read a chip that way. After verifying pinout through markings on the chip & connections in the machine. Practically all system ROMs I have, have been saved that way. Exactly BECAUSE

Take eg. a cartridge that has ROM in 4000-BFFFh area. Read out using software, program into a 27C256, put in place of the ROM in that cartridge, and you have roughly 50% chance it won't work (depending on what's connected to the highest address line on the ROM socket). FDC registers masking a few bytes from a diskROM, etc. Just a few examples.

Only exception is when you know how a ROM is connected in the machine, know its type & pinout, know that nothing interferes when read out through software, know how the data maps to what you'd program into a (flash?) EPROM, and format contents of that file accordingly. In the 27C256 example above, that could mean swapping both halves of the file's contents. If a cartridge builder had fun & swapped data or address lines around, that would be a 'fun' job software wise.

Note that getting this right is mostly relevant for hardware modders. For emulation purposes, it's more a matter of what's convenient. But it's not difficult for an emulator to use ROM data as layed out in actual chips. So why do any other way & create unnecessary confusion?

That's because some EPROMs have a self-ID function, and some programmer hardware supports that. But afaik this is limited to programmable devices: some EPROMs, and most (all?) flash EPROMs. Not mask-programmed ROMs (data hardwired in the silicon). And for none self-IDing chips, perhaps some programmer software can read bigger & smaller (EP)ROMs in the exact same way, and then apply some heuristics to figure out what size device was read.

how can you identify the pinout of mask ROMs?

Pinout can ALWAYS be determined by checking how an IC is connected in a machine. And for an (EP)ROM that's easy. You just have power/ground, a number of address lines, data lines (8 in our case), and 1 or 2 chip selects. Don't need a datasheet for that.

Just use your Google-fu. In case of doubt, just post IC markings here. Or better yet: a photo of those markings. First letters before type number usually indicate manufacturer (D.. = Nec, MB.. = Fujitsu, etc). Number in a type often indicates # of Kbits or Mbits.

If it's mass-produced then mask ROM is what you'll find. Exceptions are usually firmware unique to some model. Note that programmable parts without UV window exist (Flash -duh-, EEPROM, or One-Time-Programmable EPROM). But use of such parts in home computers is very rare afaik. Even then you could still identify that through its markings.

Btw - no schematic available for that machine of yours?