Search found 54 matches

by kpalser
Mon Dec 16, 2013 11:12 pm
Forum: Hardware
Topic: Very low signal on MIC port
Replies: 30
Views: 4139

Re: Very low signal on MIC port

In the event that my evening of experimenting might be useful to others googling this and subsequent similar threads ... My three ZX81 (like everyone else’s unmoded units) are producing a weak signal from the MIC port. Since I wanted to double check the documented: Each pulse is split into a 150us H...
by kpalser
Sun Dec 08, 2013 12:03 am
Forum: Emulators
Topic: Side margin with Z-Xtricator
Replies: 8
Views: 1934

Re: Side margin with Z-Xtricator

So after a week of evenings reviewing all timing and cycle calculations to try and account for my emulator having the equivalent of two character spaces in the left hand side (LHS) margin and six in the right (RHS), I decided to load Z-Xtricator up on a real ZX81… So obviously in the photos below I’...
by kpalser
Tue Nov 26, 2013 11:17 pm
Forum: Emulators
Topic: Side margin with Z-Xtricator
Replies: 8
Views: 1934

Re: Side margin with Z-Xtricator

Checked out Spud81 and it is the best screen centred emulator for Z-Xtricator. If you see the attached screenshot on another Software Farm hires game, in these cases Spud81 demonstrates a larger left margin and so with Z-Xtricator it looks squarely centred. (Not criticisng Spud81 - I think it is a s...
by kpalser
Mon Nov 25, 2013 9:44 pm
Forum: Emulators
Topic: Side margin with Z-Xtricator
Replies: 8
Views: 1934

Side margin with Z-Xtricator

Folks, To further my challenge of perfecting my zx81 emulator I shifted testing to focus on Z-Xtricator and its pseudo hires INT mode 2 routine. It has been an excellent exercise for identifying and correcting some flaws. Some questions: 1) Have any of you fired up Z-Xtricator on a real ZX81 recentl...
by kpalser
Sun Aug 04, 2013 8:26 pm
Forum: Emulators
Topic: Help with ZX81 loading screen for new emulator
Replies: 18
Views: 3638

Re: Help with ZX81 loading screen for new emulator

This response is mainly for Rink but the points at the end might be of general interest. To be be fair the the changes in the iOS app store are no longer recent. For a while now Apple have allowed interpreted code to run on their iOS devices. There were restrictions on the languages that could be us...
by kpalser
Sat Aug 03, 2013 7:13 pm
Forum: Emulators
Topic: Help with ZX81 loading screen for new emulator
Replies: 18
Views: 3638

Re: Help with ZX81 loading screen for new emulator

PokeMon, Thanks for the extra info and link! Sirmoris, Love to expand the emulation to include zexpand in the future, thanks for the interest. I will find the time... The emulator is quite a long term project. Since I coincidently moved to Dundee three years ago, I have interviewed workers and shop ...
by kpalser
Sat Aug 03, 2013 1:05 am
Forum: Emulators
Topic: Help with ZX81 loading screen for new emulator
Replies: 18
Views: 3638

Re: Help with ZX81 loading screen for new emulator

In my quest for improving the accuracy of the video emulation, I made an observation and hit a point that is still bugging me. Firstly, I noticed for the sudo hires Forty Niner game that the internal vertical window has to be up to around 21.3ms. If not, the program controlled vertical sync is not r...
by kpalser
Sun Jul 28, 2013 12:51 pm
Forum: Emulators
Topic: Help with ZX81 loading screen for new emulator
Replies: 18
Views: 3638

Re: Help with ZX81 loading screen for new emulator

Thanks to the replies on this thread I finally got something that resembles a loading screen. load1.png load2.png They don't quite match up to Pokemon's sample screens http://www.sinclairzxworld.com/viewtopic.php?f=7&t=1153 , but then I suspect there were some minor variations for sync pulse windows...
by kpalser
Tue Jul 02, 2013 3:20 pm
Forum: Emulators
Topic: Help with ZX81 loading screen for new emulator
Replies: 18
Views: 3638

Re: Help with ZX81 loading screen for new emulator

Again thanks for all your replies. So in summary (quick visual at the end of my lunch hour): overview.png As the shortest sync period that the IN/OUT instructions can generate is 11 processor clock cycles (22 video clock clock cycles), programatically generated pulses always have a length sufficient...
by kpalser
Mon Jul 01, 2013 7:11 pm
Forum: Emulators
Topic: Help with ZX81 loading screen for new emulator
Replies: 18
Views: 3638

Re: Help with ZX81 loading screen for new emulator

Thank you both for your replies. The information is just what I needed. I'll update my code this weekend and add the new images to this topic. A quick question: When a CRT display receives a sync pulse in the middle of video that is too short to trigger a horizontal retrace, would I be correct in ou...