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43

There are several aspects to consider to answer your question. The x86 architecture is backwards-compatible with the first CPU of the line, the 8086 (and its sibling, the 8088). What this means is that, when a modern Intel (or AMD) processor boots up, it starts in a mode which is compatible with the 8086 — if the motherboard's BIOS support is good enough, ...


28

The 8086 is source-code compatible with the 8080 (the other way around is not true). This means that most assembly code written for the 8080 can be assembled so that 8086 instructions are emitted. The only exceptions would be self-modifying code or code that relies on interrupts, which are handled differently on both processors. In fact, some assemblers, ...


19

A few 16-bit processors can run 8-bit code: the NEC V20 series. The V20 and V30 are the ones you might encounter in a PC. The V20 is a pin-compatible substitute for the 8088, and the V30 for the 8086. These processors have a BRKEM instruction (in Intel's notation it would most likely be 'INTEM') which switches to the 8080 instruction set and jumps to an ...


15

There is no such thing as an 8-bit application for the x86 architecture, because the x86 architecture has always been at least 16-bit right from the first generation of x86 processors. The x86 does allow access to 8-bit registers, but the code is still 16-bit and the processor is still running as a 16-bit processor. Of course, if you're trying to run 8-bit ...


9

rlogin and rcp are considered to be somewhat obsolete nowadays and have been replaced by ssh and scp respectively, the first "s" standing fore "secure". The reason I am telling you this is that both ssh and scp connect to the sshd server via port 22. Coincidence? I think not. Your host system does not have a true rcp or rlogin and has instead aliased both ...


7

As mcleod_ideafix pointed out, the x86 architecture is source-compatible with the x80 architecture. This basically means that if you have the original assembly file of a program, you can rougly translate it to x86 bytecode. Of course, you still need some form of assembly file to compile it, but you might have a look at Dynamic Recompilation. However, just ...


7

ToolShed seems to be the current maintained OS9/descendants disk manager tool. It's not a file browser but works on the command line. Are you sure your disk image is a valid RBF image, though? Toolshed refuses to read it: $ os9 dir os9000-xibase.img dir: error 216 opening 'os9000-xibase.img,' dir: error 216 opening 'os9000-xibase.img' Similarly, checking ...


5

Some supplemental things: Years ago, I used a program that emulated 8 bit CP/M on 16 bit DOS machines that were not the special NEC V20/V30 nor the dual-CPU AT&T design. It worked quite well and was not that much slower than the real thing. And since modern x86_64 CPUs can still run DOS, that program would still work if I could find it. x86_64 CPUs ...


3

There's reason to believe that this is a qemu bug (actually a problem caused by the configuration of SeaBIOS in qemu 3.0 and 3.1). If this is the case, the CD driver will work fine in qemu 2.12.1 or older (SeaBIOS will be 1.11.1 or older), or qemu 4.0.0 or newer (SeaBIOS will be 1.12.1 or newer). A qemu displaying a SeaBIOS version of 1.11.2 or 1.12.0 will ...


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