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Re: [f-cpu] Erin64 Boot-Load Process
hello,
thank you for your description.
One must however point that Erin64 is pretty different
from F-CPU because
- Erin uses a pre-defined software with a specific
task and goal (F-CPU is a "general purpose CPU")
- Erin does not handle memory the same way (F-CPU uses
virtual memory, user and superuser attributes, ...)
so the comparison is not straight-forward.
This is why your description seems unclear in certain parts,
at least to me.
> richard hartny wrote:
> The Erin64 has a very simple process using "Flash Memory" as follows:
>
> 1. Issue Global Reset
that is : an electric signal (as opposed to "signals" in UNIX jargon)
> 2. Clear Program & Local Memory, Language Processor
> and Peripheral Processor
i understand that RESET can flush the program counter,
for example, but there is usually no "clear memory" signal
in the RAM chips. Does that mean that there's a software routine
that flushes memory ? This also means that the instruction
decoding has already started, unless you have a specific
state machine for this task.
> 3 Write Program & Local Memory, both processors
write with what ? copy from the Flash ?
> 4. Initialize Character Generators
with a SW routine ?
> 5. Issue "RUN" to both Processors
what is this "issue" mechanism ? Is it HW or SW ?
> 6. Both Processors commence an "Initialize Routine"
> starting at address Zero. Upon completion both
> Processors execute a HLT Instruction with Interrupts
> Enabled. The Processors have nothing to process
> untill a USER at a one of 128 Terminals makes either
> a Keyboard entry or a Mouse Click selection. Or if an
> Inter-system Interrupt (ISI) request comes via the
> Expansion Port to the Peripheral Processor for a
> Hard Disk operation.
>
> For what it's worth
best regards,
> Dick Hartney
WHYGEE
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