MEM11 Status Update

[Guy Sotomayor]

On 8/30/15 12:50 AM, Henk Gooijen wrote:
> -----Oorspronkelijk bericht----- From: Guy Sotomayor Sent: Sunday, 
> August 30, 2015 7:05 AM To: General Discussion: On-Topic and Off-Topic 
> Posts Subject: MEM11 Status Update
> [... snip ...]
> The biggest piece of work remaining on the emulator will be emulating the
> Unibus interface.  The work here will mainly to create a means to script
> various Unibus transactions.
>
> However, before doing that, I'll be testing out the boot loader code and
> the configuration firmware since none of that is dependent upon the
> existence of functional Unibus hardware.
>
> TTFN - Guy
>
> ------------
> Guy,
> as you have sort-of all possible UNIBUS transactions because
> of the devices supported by the MEM11, I guess there is still
> so work to do ;-)
> One question came to my mind.
> Suppose I manage to "crash" the board in such a bad way that
> it does not start up anymore. Is there a jumper to force it to
> execute a "golden boot"? That is, load a minimal "kernel" to
> bring the MEM11 back to life to reload the bootloader and
> firmware?
> Shipping a dead MEM11 back to the Creator inside USA is
> OK, but from Europe etc. might get costly. And Customs
> probably wants to put tax on it when shipped back from you.
>

Yea, I'm trying to avoid having folks to send stuff back to me.

The FRAM map that I'm currently working with has locations
for 5 complete firmware images.  The bootloader and Config
Mode firmware all have support for this.  Here's what they are for:
      - 2 sets of Config Mode images.  This allows for downloading
         a new image while still keeping the previous one around.
      - 2 sets of Run Mode images.  This allows for downloading
         a new image while still keeping the previous one around.
      - a "safe" Config Mode image.  This image will be used when
         the jumpers are set to "safe" mode or the boot loader
         determines that the selected image isn't bootable.  This
         image is *not* writable by the MEM11 firmware.  I *may*
         decide to physically write protect it (the FRAM allows me to
         write protect sections).

I'm seriously contemplating putting something in the cold boot
code (initial J1 RAM contents) that allows for downloading
image contents into FRAM.  This would help me out when I'm
bringing up an individual board for the first time (ie manufacturing).
It would also allow for recovery if the safe boot image became
corrupted for some reason.

I'm hoping that with all of the above, the only time a board would
have to be shipped back to me would be in the case of a HW failure.

TTFN - Guy