Binary words in MC68000 are MSB LSB but the same on intel will
be LSB MSB
(and the Z80 is that way araoiund as well).
Why ?
Must be a hardware thing, I always write my numbers MSB LSB myself.
The reason, as I heard it, was to save clock cycles in indexed addressing modes. If
you fetch the LSB of the address/offset first, you can be adding the LSB of the
index/base to it while fetching the MSB. Intel CPUs did not have indexed addressing
until 8086/88 so the technique was redundant really. The 6502 had indexed addressing
and 8 bit ALU so little-endian architecture did save clock cycles. I guess the
designers fall into either the big-endian or little-endian camps and stay there, even
when they move on and set up new companies, or new product ranges. Once you've
chosen a particular architecture, compatibility across the range becomes a
consideration too.
Ian.
-Original Message-
From: Norman Dunbar [mailto:[EMAIL PROTECTED]]
Sent: 24 April 2002 11:29
To: '[EMAIL PROTECTED]'
Subject: RE: [ql-users] QXLWIN v1.06 and partitions
Wolfgang,
it's not 'stupid' it's Intel 'little Endian' format.
OK, it *is* stupid :o)
Binary words in MC68000 are MSB LSB but the same on intel will
be LSB MSB
(and the Z80 is that way araoiund as well).
Why ?
Must be a hardware thing, I always write my numbers MSB LSB myself.
I'm sure Nasta will know why it is/was done this way around.
Cheers,
Norman.
-
Norman Dunbar
Database/Unix administrator
Lynx Financial Systems Ltd.
mailto:[EMAIL PROTECTED]
Tel: 0113 289 6265
Fax: 0113 289 3146
URL: http://www.Lynx-FS.com
-
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, April 24, 2002 11:22 AM
To: [EMAIL PROTECTED]
Subject: Re: [ql-users] QXLWIN v1.06 and partitions
On 23 Apr 2002, at 16:27, Phoebus Dokos wrote:
Yep it works and the interesting part is that unfortunately
he cannot test
it himself as his CF adapter has some problems which I hope
he'll soon
solve either by a minor change or by a replacement (by me).
Talk about SuperScalar programming... It works even if you
don't use the
device yourself!
Well, all the kudos here must go to hell, I don't know, whoever
is responsible for the Compact Flash reader behaving like a hard
drive.
Actually, you just open a winx_*d2d file to the hard disk that is
the compact flash reader. With one exception, it then behaves like
a normal hard disk. So, to test this I just used another partition...
The exception is that a compact disk stroes bytes within a word in
teh wrong order. Normally, the first four bytes in a QL hard disk
partition are QLWA. Don't ask me what it means, I can undertand
the QL part, but the rest...
Well, anyway, on a compact flash, this would be LQAW. Stupid,
really. The software takes care of that.
Oh, and whilst we're talking about partitions, there is a curious
feature of partitions and accessing them via a winx_*d2d file on
the Q60.
Suppose you have a hard disk with 3 partitions (all 3 of them QL
partitions of course, none of that Linux stuff :-) )
You would probably use something like:
win_drive 1,0,0,0
win_drive 2,0,0,1
win_drive 3,0,0,2
to access the different partitions. You would then expect a
win3_*d2d direct sector access file to open to the 3rd partition on
the drive - not so, IT WILL OPEN to the very first sector of the
physical disk (i.e. the partition table)- the same for win1_*d2d and
win2_*d2d.
It's not a problem, as long as you are aware of this.
Wolfgang
This email is intended only for the use of the addressees
named above and
may be confidential or legally privileged. If you are not an
addressee you
must not read it and must not use any information contained in
it, nor copy
it, nor inform any person other than Lynx Financial Systems or the
addressees of its existence or contents. If you have received
this email
and are not a named addressee, please delete it and notify the Lynx
Financial Systems IT Department on 0113 2892990.
Visit our website at http://www.ubswarburg.com
This message contains confidential information and is intended only
for the individual named. If you are not the named addressee you
should not disseminate, distribute or copy this e-mail. Please
notify the sender immediately by e-mail if you have received this
e-mail by mistake and delete this e-mail from your system.
E-mail transmission cannot be guaranteed to be secure or error-free
as information could be intercepted, corrupted, lost, destroyed,
arrive late or incomplete, or contain viruses. The sender therefore
does not accept liability for any errors or omissions in the contents
of this message which arise as a result of e-mail transmission. If
verification is required please request a hard-copy version. This
message is provided for informational purposes and should not be
construed as a solicitation or offer to buy or sell
