FlashbackSE misbehaving on Q68

Anything QL Software or Programming Related.
Derek_Stewart
QL Wafer Drive
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Joined: Mon Dec 20, 2010 11:40 am
Location: Runcorn, Cheshire, UK

Re: FlashbackSE misbehaving on Q68

Postby Derek_Stewart » Sat Jun 22, 2019 11:01 am

Hi,

There has been an in depth investigation into Flashback running on the Q68.

The origins of the problem is that there are several places throughout the code which do:

move.b #0,$34(a1) (a1 points to the sysvars)
move.b #0,$18063 !! direct write to display mode reg

These instructions make a change to the screen mode by poking values directly into control register. The software has no business doing that and, as you can see, this screws things up.

This means that Q68 SMSQ/E (which doesn't know about the screen change) and the hardware no longer are in agreement, which crashes the machine (Q68 SMSQ/E still uses the higher colour screen driver).

Since SMSQmulator simply ignores these sysvars, it isn't affected by the writes to them, QPC2 seems to accept the write to the display register.

Flashback is programmed to access the QL screen directly, which the Q68 does not have, which is not good programming style.

There is a fix, but since Flashback is still commercial software is subject to copyright, only the copyright holder can alter the software or give authorisation for alteration.

To date the copyright holder is not responding to any communications.


Regards,

Derek
Ralf R.
Over Heated PSU
Posts: 133
Joined: Fri Jun 15, 2018 8:58 pm

Re: FlashbackSE misbehaving on Q68

Postby Ralf R. » Sat Jun 22, 2019 12:18 pm

Derek_Stewart wrote:To date the copyright holder is not responding to any communications.


I'm not surprised. There were a lot of complaints about that in the past. Any chance to contact Peter Jefferies directly?

Does the "copyright holder" really believe, that anyone would buy this program these days from him? Seems to be similar to text87.


Derek_Stewart
QL Wafer Drive
Posts: 1436
Joined: Mon Dec 20, 2010 11:40 am
Location: Runcorn, Cheshire, UK

Re: FlashbackSE misbehaving on Q68

Postby Derek_Stewart » Sat Jun 22, 2019 4:33 pm

Hi Ralf,

Flashback was supplied by Sector Software, requests have made to David Batty, to relase Flashback as freeware. When this happens, the bugs in the software can fixed.


Regards,

Derek
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BSJR
Chuggy Microdrive
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Location: Amsterdam
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Re: FlashbackSE misbehaving on Q68

Postby BSJR » Tue Jun 25, 2019 11:05 am

Derek_Stewart wrote:Hi Ralf,

Flashback was supplied by Sector Software, requests have made to David Batty, to relase Flashback as freeware. When this happens, the bugs in the software can fixed.

Many thanks Derek and other persons involved in locating this bug.
I will have to avoid using FB on my Q68 for now.

BSJR


Ralf R.
Over Heated PSU
Posts: 133
Joined: Fri Jun 15, 2018 8:58 pm

Re: FlashbackSE misbehaving on Q68

Postby Ralf R. » Tue Jun 25, 2019 4:48 pm

Derek_Stewart wrote:There is a fix, but since Flashback is still commercial software is subject to copyright, only the copyright holder can alter the software or give authorisation for alteration.

I think, it would be save to just give the user a little SB program to patch their own FBSE. This seems to be save, as noone else can use such a program. Isn't it?


Derek_Stewart
QL Wafer Drive
Posts: 1436
Joined: Mon Dec 20, 2010 11:40 am
Location: Runcorn, Cheshire, UK

Re: FlashbackSE misbehaving on Q68

Postby Derek_Stewart » Tue Jun 25, 2019 6:53 pm

Hi Ralf,

A patch programme would be a solution, but does the application of the patch break the copright ?

A better solution may be to disassemble the programme, correct the faults and change the name calling it "FlashyBackerDbase".

I have been reading the Flashback manual, , I do not like it, which why I did not buy it.


Regards,

Derek

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