[E3-hacking] Config / content filesystem

[Nick Griffin]

Thanks btw Ralph.. 😊

Spanner..

http://amstrad-e3-hacking.freeforums.net

From: David Given<mailto:dg at cowlark.com>
Sent: ‎Wednesday‎, ‎24‎ ‎April‎ ‎2019 ‎10‎:‎50
To: Discussion of the Amstrad E3 emailer hardware/software<mailto:e3-hacking at earth.li>

The E3 is based on an ARM reference design, isn't it? What's the feasibility of emulating one?

On Wed, 24 Apr 2019 at 11:46, Ralph Corderoy <ralph at inputplus.co.uk<mailto:ralph at inputplus.co.uk>> wrote:
Hi Nick,

> > That should be possible as you have the files, now without their 16
> > bytes per 512 bytes overhead.  You need to work out how many blocks
> > to erase based on the size of each file you're trying to put back.
> > IIRC I pointed out a block is the unit of erasure and it's 16 KiB.
>
> So e3-nand.0 is 3584 KB so how many blocks go into it…? so how many
> times dose 16KB going in to 3584KB…?? I don’t know..?? I can’t divide.
> Iam a bit ok on Add not brilliant at Times but can’t do Divide.

Having stripped the excess OOB data, I have these sizes for each file in
bytes.

     3670016  e3-nand-backup.0
      262144  e3-nand-backup.1
      262144  e3-nand-backup.2
      262144  e3-nand-backup.3
    28311552  e3-nand-backup.4
      786432  e3-nand-backup.5

You're right, 3,670,016 B is 3,584 KiB because
    3,670,016 / 1,024 = 3,584
so 1,024 goes into 3,670,016 exactly 3,584 times.

But the size of the erase block is 16 KiB which is
    16 * 1,024 = 16,384
so we want to know how many times 16,384 goes into 3,670,016.
    3,670,016 / 16,384 = 224
224 is what you worked out in your other email.

Taking those six sizes above and repeating the same sum gives

     3,670,016 / 16,384 =   224
       262,144 / 16,384 =    16
       262,144 / 16,384 =    16
       262,144 / 16,384 =    16
    28,311,552 / 16,384 = 1,728
       786,432 / 16,384 =    48

Now I haven't been carefully following along how to extract
e3-nand-backup.* in the first place, and how to write them back.
I'm aware there's a script involved and a command where one of the
parameters is the number of 16 KiB blocks to erase.  Hopefully, plugging
in those numbers above for each of the matching areas will work, but
it's your responsibility whether to go ahead as you're the one actually
doing all this;  I've just been sitting at a keyboard.  :-)

--
Cheers, Ralph.

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