Search found 1007 matches

by Peter
Thu Oct 24, 2013 10:59 am
Forum: Hardware
Topic: QL-SD card project
Replies: 43
Views: 14943

Re: QL-SD card project

Thanks. Should have known you made a neat solution. :D Unfortunately I own no Aurora system - would be interesting to see if my SGC becomes stable with QL-SD then.
by Peter
Tue Oct 22, 2013 9:23 pm
Forum: For Sale
Topic: Sinclair QL Floppy Disk Interfaces
Replies: 47
Views: 12589

Re: Sinclair QL Floppy Disk Interfaces

Normally, SRAM helps simplify designs if you do have a huge budget. ;) It is far more expensive - just the small size needed for traditional QL purposes makes the price irrelevant.
by Peter
Tue Oct 22, 2013 2:49 pm
Forum: Hardware
Topic: QL-SD card project
Replies: 43
Views: 14943

Re: QL-SD card project

Or not break the form factor by adding components, but go back to a classic 5V PLD. Or move things out to the external ROM port, as signal quality seems somewhat better there. The more basic question is, wether to continue tinkering or not. I tend to say, the device should become available as it is....
by Peter
Tue Oct 22, 2013 1:01 am
Forum: For Sale
Topic: Sinclair QL Floppy Disk Interfaces
Replies: 47
Views: 12589

Re: Sinclair QL Floppy Disk Interfaces

I have that too, but isn't it a pain? Characters are hardly legible in 512x256, and single pixels (e.g. at the border) can not be distinguished. Do you use it in 256x256 only?
by Peter
Mon Oct 21, 2013 10:19 pm
Forum: For Sale
Topic: Sinclair QL Floppy Disk Interfaces
Replies: 47
Views: 12589

Re: Sinclair QL Floppy Disk Interfaces

I just wonder all the time, why nobody complains about the lack of flatscreen monitor support for the QL. Storage is obviously important, but I have no idea how to achieve a decent 512x256 QL display nowadays. Do you all press F2 and use TV mode? Or do you all still own working CRT monitors?
by Peter
Mon Oct 21, 2013 9:44 pm
Forum: Hardware
Topic: QL-SD card project
Replies: 43
Views: 14943

Re: QL-SD card project

A question. Could some of the problems be due to a poor ground layout / tracks? Are you seeing a form of "ground bounce" where the voltage drop through the ground is helping to cause the voltage on the signal lines to be out of spec? Mark Yes the QL mainboard ground layout is poor and inv...
by Peter
Mon Oct 21, 2013 9:21 pm
Forum: For Sale
Topic: Sinclair QL Floppy Disk Interfaces
Replies: 47
Views: 12589

Re: Sinclair QL Floppy Disk Interfaces

As for my knowledge: Obviously it was not sufficient to foresee the problems QL-SD would suffer from. I was more used to newer designs like the Q68 and Q60, where you have decent signal quality due to adequate routing and ground planes. The QL motherboard was never designed to satisfy >300 MHz logic...
by Peter
Mon Oct 21, 2013 8:42 pm
Forum: Hardware
Topic: QL-SD card project
Replies: 43
Views: 14943

Re: QL-SD card project

Yes, I know, it's never that simple :-( Mark And here's one of the examples why: Noisy low-level address signal at 1.2V during ROMOE active-high. (Scope has persistance on, address signal on top.) To deal with this kind of noise, the adress line is sampled at ROMOE rising edge, where there is less ...
by Peter
Mon Oct 21, 2013 7:08 pm
Forum: Hardware
Topic: QL-SD card project
Replies: 43
Views: 14943

Re: QL-SD card project

This picture shows the ROMOE signal on my SuperGoldCard QL, which is used as an imput to QL-SD. The horizontal dotted line is the maximum allowed low level TTL voltage of 0.8V. The measured signal illegally goes up to 1.5V where logic level is low. The oscilloscope has a bandwidth of 60 MHz only, so...
by Peter
Mon Oct 21, 2013 4:42 pm
Forum: For Sale
Topic: Sinclair QL Floppy Disk Interfaces
Replies: 47
Views: 12589

Re: Sinclair QL Floppy Disk Interfaces

This was about a Super Gold Card remake: You can always get a newer model and just port the logic code to the newer chip. On the VHDL level, it's a day's work tops and Altera will have guides (if not porting tools too) to tell you how. Firstly, complex ancient logic code can be hard to port to newer...