I know that many low-end machines with a 286 processor used it only as fast 8088: the Tandy 1000 TX or TL, or many 286 accelerator cards for XTs. No 16-bit bus, no extended memory, no A20 line. So the usual verdict is they "can't run protected mode."
My question is: does that mean only "no Windows or DOS extender protected mode", or does that mean "protected mode is impossible so you can't even start it" for those machines?
I'm thinking of a simple demonstration program like the one mentioned in the "A toy protected mode program question" thread. If you wrote a custom program in assembly, setting up the GDT and IVT descriptors entirely in conventional memory and switched to protected mode, only touching hardware directly, surely the 286 would execute it? It wouldn't be DOS compatible at all, and you couldn't exit without rebooting, but has any TX owner ever tried it? Or are those machines specifically designed to defeat that, such as instantly rebooting when a switch to protected mode is detected? (Even then, at the very least I would expect LOADALL to work.)
I just wonder if anyone has ever performed the experiment on one of those low-end 286s.
My question is: does that mean only "no Windows or DOS extender protected mode", or does that mean "protected mode is impossible so you can't even start it" for those machines?
I'm thinking of a simple demonstration program like the one mentioned in the "A toy protected mode program question" thread. If you wrote a custom program in assembly, setting up the GDT and IVT descriptors entirely in conventional memory and switched to protected mode, only touching hardware directly, surely the 286 would execute it? It wouldn't be DOS compatible at all, and you couldn't exit without rebooting, but has any TX owner ever tried it? Or are those machines specifically designed to defeat that, such as instantly rebooting when a switch to protected mode is detected? (Even then, at the very least I would expect LOADALL to work.)
I just wonder if anyone has ever performed the experiment on one of those low-end 286s.