On 9/25/2019 9:23 AM, dmccunney wrote:
Why would they do that? To create much simpler OS for RPI than Linux. Who
needs that whole complexity on such little SBC? CP/M would do just fine.
No, it wouldn't. Digital Research developed CP/M as an OS for 8 bit
micros like the Intel 8080 and Zilog Z80. They were single tasking
CPUs supporting a whopping *64K* of address space. OS, applications,
and data all had to fit into 64K.
DR offered CP/M not only for the 8080/8085/Z80 8 bit processors, but
also for Intel 8086 (x86), Motorola 680x0 and Zilog Z8000 CPUs, and at
least the last two don't have a 64K address space limitation...
The Raspberry Pi uses an ARM Cortex CPU, with a 32bit address space
and a multi-core design. It can run a full multi-user, multitasking
OS like Linux, and does. And ARM CPUs are often used in Internet of
Things devices. The critical point is the the CPU can run a full
TCP-IP networking stack, and become a node *on* the Internet. A
second critical point is the the costs of such CPUs have dropped to
the point where you *can* affordably use something like a a 32bit ARM
CPU in an embedded device.
Actually Current CP/M-86 and MP/M were CP/M versions that were
multi-user and networkable (though no Internet existed those days,
fortunately)...
Ralf
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