Date : Wed, 11 May 2005 10:16:19 +0100 (BST)
From : Steve Fewell <kranser@...>
Subject: Re: Beeb versus Master?
--0-1256631272-1115802979=:27955
The BBC Master welcome disk also came with a program which, when loaded,
would allow most of the non-working BBC B software to work.
It would be interesting to find out what this program does!
Steve Fewell
-----Original Message-----
From: Majordomo List Manager [mailto:majordomo@...] On Behalf Of
Richard Gellman
Sent: 10 May 2005 09:45
To: bbc-micro@...
Subject: Re: [BBC-Micro] Beeb versus Master?
The only "it don't work on a Master" issues are that of undocumented opcodes,
and the character definition space.
The former is only really a problem for games that use undocumented opcodes
for performance reasons. Most control software do things properly, so Master-ability
is not a problem. Also to note is that, the opcode issue died out around
1988/89 after all the software companies realised their stuff didn't work
on the M128, and recoded it to work correctly. Thus, most games do actually
work fine on ye olde M128.
The second issue is one of laziness on the part of the software author.
VDU 23 (OSWRCH 23 in assembly terms) is used to redefine the appearance of
characters in modes 0-6. In the Model B, these are held in "Low"
(below &8000) RAM, in a specific location. They also require the use of
a *FX (OSBYTE) sequence to access some of them. In the Master 128, they are
held in High RAM, in a private address space. Now to the VDU 23 user, there
is no difference in use, but...
... Some dodgy software manufacturers (and I've seen educational control
software do this, albeit for its title screen only) just make the appropriate
*FX call, load a block into memory, and get on with things, assuming MOS
will just use the data its given, with no thought for checking OS version.
The net effect of this is that some things look like they're written in quasi-arabic,
rather than a full-out crash (as with the undoc'd opcodes).
To summarise: The Master 128 is technically superior, and 98% of the time
it will run BBC B stuff without problems. But the occasional piece of software
written by lazy monkeys might have odd behaviour.
I personally would never give up my lovely M128 (with 65C102 Internal Second
processor, *cough*, Tube Elite anyone?).
-- Richard
P.S. Has anyone else been receiving spam via this list? Given that posts
are supposed to require your sending email address matches that which you
subscribed with, I find it interesting that spam is making it through...
neil f wrote:
>I have the choice of standardising on a Master 128 or building a
>heavily upgraded B. (It needs to be M OR B as I don't want too much
>extra hardware hanging around - I'm tripping over stuff all day as it
>is.) My main interest is in interfacing (science projects, robotics
>etc) with just the odd game played for old time's sake. Leaving aside
>the smaller footprint and much more attractive case of the B, are there
>any other advantages to it that I'd be missing? I'm assuming the Master
>is electrically similar or superior to the B, but are there software
>issues that make certain programs unavailable on the Master for
>instance. Any other issues I should consider. I have most of what I
>would need to go down either route, so cost is not an issue at this stage.
>
>Cheers,
>-Neil F.
>
>
>
Yahoo! Messenger - want a free & easy way to contact your friends online?
--0-1256631272-1115802979=:27955
<DIV><FONT size=2>
<P>The BBC Master welcome disk also came with a program which, when loaded,
would allow most of the non-working BBC B software to work.</P>
<P>It would be interesting to find out what this program does!</P>
<P>Steve Fewell</P>
<P>-----Original Message-----</P>
<P>From: Majordomo List Manager [</FONT><A href="mailto:majordomo@..."><U><FONT
color=#0000ff size=2>mailto:majordomo@...</U></FONT></A><FONT size=2>]
On Behalf Of Richard Gellman</P>
<P>Sent: 10 May 2005 09:45</P>
<P>To: bbc-micro@...</P>
<P>Subject: Re: [BBC-Micro] Beeb versus Master?</P>
<P>The only "it don't work on a Master" issues are that of undocumented opcodes,
and the character definition space.</P>
<P>The former is only really a problem for games that use undocumented opcodes
for performance reasons. Most control software do things properly, so Master-ability
is not a problem. Also to note is that, the opcode issue died out around
1988/89 after all the software companies realised their stuff didn't work
on the M128, and recoded it to work correctly. Thus, most games do actually
work fine on ye olde M128.</P>
<P>The second issue is one of laziness on the part of the software author. </P>
<P>VDU 23 (OSWRCH 23 in assembly terms) is used to redefine the appearance
of characters in modes 0-6. In the Model B, these are held in "Low" </P>
<P>(below &8000) RAM, in a specific location. They also require the
use of a *FX (OSBYTE) sequence to access some of them. In the Master 128,
they are held in High RAM, in a private address space. Now to the VDU 23
user, there is no difference in use, but...</P>
<P>... Some dodgy software manufacturers (and I've seen educational control
software do this, albeit for its title screen only) just make the appropriate
*FX call, load a block into memory, and get on with things, assuming MOS
will just use the data its given, with no thought for checking OS version.</P>
<P>The net effect of this is that some things look like they're written in
quasi-arabic, rather than a full-out crash (as with the undoc'd opcodes).</P>
<P>To summarise: The Master 128 is technically superior, and 98% of the time
it will run BBC B stuff without problems. But the occasional piece of software
written by lazy monkeys might have odd behaviour.</P>
<P>I personally would never give up my lovely M128 (with 65C102 Internal
Second processor, *cough*, Tube Elite anyone?).</P>
<P>-- Richard</P>
<P>P.S. Has anyone else been receiving spam via this list? Given that posts
are supposed to require your sending email address matches that which you
subscribed with, I find it interesting that spam is making it through...</P>
<P>neil f wrote:</P>
<P>>I have the choice of standardising on a Master 128 or building a </P>
<P>>heavily upgraded B. (It needs to be M OR B as I don't want too much </P>
<P>>extra hardware hanging around - I'm tripping over stuff all day as it </P>
<P>>is.) My main interest is in interfacing (science projects, robotics </P>
<P>>etc) with just the odd game played for old time's sake. Leaving aside </P>
<P>>the smaller footprint and much more attractive case of the B, are
there </P>
<P>>any other advantages to it that I'd be missing? I'm assuming the Master
</P>
<P>>is electrically similar or superior to the B, but are there software </P>
<P>>issues that make certain programs unavailable on the Master for </P>
<P>>instance. Any other issues I should consider. I have most of what I </P>
<P>>would need to go down either route, so cost is not an issue@...
stage.</P>
<P>></P>
<P>>Cheers,</P>
<P>>-Neil F.</P>
<P>></P>
<P>> </P>
<P>></P></FONT></DIV><p>
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--0-1256631272-1115802979=:27955--