Search found 344 matches

by Nasta
Wed Jun 26, 2019 9:33 am
Forum: Software & Programming
Topic: Hardware pointers and cursors.
Replies: 30
Views: 4230

Re: Hardware pointers and cursors.

I've never used the PE for longer than it takes to disable it. In that brief time I have observed that it displays a no entry symbol of red on white, and a pointer of two colours, and sometimes a question mark of two colours. I have never been exposed to how they are internally formatted. Even the ...
by Nasta
Wed Jun 26, 2019 2:24 am
Forum: Software & Programming
Topic: Hardware pointers and cursors.
Replies: 30
Views: 4230

Re: Hardware pointers and cursors.

To make a long story short, the gain in responsiveness will be disappointingly small if at all observable. And it will come at considerable complication to drivers, because under PE the cursor can be more than a 2-bit deep bitmap with the given hardware limitations. The OS updates the cursor under ...
by Nasta
Tue Jun 25, 2019 12:19 am
Forum: Software & Programming
Topic: Hardware pointers and cursors.
Replies: 30
Views: 4230

Re: Hardware pointers and cursors.

To make a long story short, the gain in responsiveness will be disappointingly small if at all observable. And it will come at considerable complication to drivers, because under PE the cursor can be more than a 2-bit deep bitmap with the given hardware limitations. The OS updates the cursor under v...
by Nasta
Sun Jun 09, 2019 3:40 pm
Forum: Hardware
Topic: Symmetric multiprocessing...
Replies: 52
Views: 7675

Re: Symmetric multiprocessing...

Also, the 68K vector area and etc. are so small, it might be unnecessary to remap the DPRAMs, IF they do not conflict with a ROM image. I haven't tackled that part of the design yet. you can use the FC0-FC2 to signal a fetch of restart vector - as it's different to other vector fetches - and could ...
by Nasta
Sun Jun 09, 2019 11:53 am
Forum: Hardware
Topic: Symmetric multiprocessing...
Replies: 52
Views: 7675

Re: Symmetric multiprocessing...

...needs some refinement to the hardware it it's going to run useful code. Some of it can be implemented using extra features present on DPRAM chips, depending on the actual chip. Also, some form of interrupt is needed if any kind of kernel is to run, to provide a periodic tick. Similar to QDOS, at ...
by Nasta
Thu Jun 06, 2019 4:12 pm
Forum: Hardware
Topic: Symmetric multiprocessing...
Replies: 52
Views: 7675

Re: Symmetric multiprocessing...

May I interject with some thoughts before this gets a bit out of hand? Having some decade+ experience with various modes of multiprocessing (you would not believe how some apparently mundane applications can get heavily multi-processed once security and redundancy come into play), and even a diploma...
by Nasta
Mon Jun 03, 2019 7:25 pm
Forum: Hardware
Topic: Asymmetric multiprocessing...
Replies: 71
Views: 8985

Re: Asymmetric multiprocessing...

I don’t think there will be very much interest in this subject unless some software is developed that makes good use of the concept - a killer app so to speak. But anyway... The documentation clearly shows that the Acorn Tube is designed around using the BBC operating system, and this extends down ...
by Nasta
Mon Jun 03, 2019 11:28 am
Forum: Hardware
Topic: Asymmetric multiprocessing...
Replies: 71
Views: 8985

Re: Asymmetric multiprocessing...

Getting back to the real question, do you want a low cost, but very high performance second processor? If the answer is yes, it makes sense to make the interface compatible with the Acorn Tube. By the same token it's an even better idea to implement a socket for a modern Intel PC processor... The d...
by Nasta
Mon Jun 03, 2019 12:10 am
Forum: Hardware
Topic: Symmetric multiprocessing...
Replies: 52
Views: 7675

Re: Symmetric multiprocessing...

If there was ever a Pandora's box of a topic, here it is.
That being said, it's REALLY important to know what symmetric processing is, and how many different kinds there are, to give the topic a proper treatment.
by Nasta
Sat May 11, 2019 1:31 pm
Forum: Hardware
Topic: PC mouse to QL conversion project
Replies: 27
Views: 4084

Re: PC mouse to QL conversion project

Hi, The multiplexing scheme simply makes a logical 'OR' function between the incoming data on the two ports, and relies on just one transmitting That explains that nicely. Reading QL wiring schematics now makes sense. RXD(SER2), TXD(SER1), are fed through two NOR-NAND gates, to drive INT of IPC, th...