Re: [f-cpu] Erin64 Boot-Load Process

[Yann Guidon <whygee@f-cpu.org>]

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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