Search found 68 matches

by kpalser
Thu Jan 23, 2020 9:27 pm
Forum: Emulators
Topic: Emulating musical tones using cassette out - help!
Replies: 7
Views: 1806

Re: Emulating musical tones using cassette out - help!

Indeed, the code is used only for the first value in the sound buffer after an IN or OUT. The "newpos" and "subpos" variables are calculated like an integer division and a remainder. So I guess the "subpos" variable smoothes things a bit by not taking the initial value itself, but taking into accou...
by kpalser
Tue Jan 21, 2020 10:06 pm
Forum: Emulators
Topic: Emulating musical tones using cassette out - help!
Replies: 7
Views: 1806

Re: Emulating musical tones using cassette out - help!

Hi Mark, All very well described. Thank you. In a real ZX80 or ZX81, it does not matter if the digital output ends up at a logic high or a logic low ... the output at the mic socket will always change towards the 0V / ground level (silence as far as audio systems are concerned) shortly after any act...
by kpalser
Tue Jan 21, 2020 9:13 am
Forum: Emulators
Topic: Emulating musical tones using cassette out - help!
Replies: 7
Views: 1806

Re: Emulating musical tones using cassette out - help!

Hi Erik & Mark, Thank you both for responding. I see things more clearer now. Some quick thoughts: 5. If the signal is taken to decrease linearly (rather than exponentially) to the silence level, the beeper volume may perhaps be used to efficiently calculate the range of positions in the waveform wh...
by kpalser
Sun Jan 19, 2020 7:45 pm
Forum: Emulators
Topic: Emulating musical tones using cassette out - help!
Replies: 7
Views: 1806

Emulating musical tones using cassette out - help!

Hi All, I’m in the process of adding sound support to my ZX81 iOS emulator app that will be compatible with programs like Kelly Murta's 2005 ZX81 Music Interpreter. The emulator has already had AY support for about 2 years now. To be frank, there are too many holes in my understanding of the mechani...
by kpalser
Sat Jan 18, 2020 2:11 pm
Forum: GAMES
Topic: Cassette60 : the 1K hires games
Replies: 9
Views: 2012

Re: Cassette60 : the 1K hires games

Simon wanted a working or not. Not defined that some machines might not work. This to prevent taking back sales. Understood - It is difficult not to agree with his decision. Bigger picture: It would be helpful to the ZX81 community to determine why WRX does not work with all unexpanded ZX81 issues/...
by kpalser
Sat Jan 18, 2020 10:51 am
Forum: GAMES
Topic: Cassette60 : the 1K hires games
Replies: 9
Views: 2012

Re: Cassette60 : the 1K hires games

Simon tested several ZX81. Some work, some not. Was there a clear pattern where there same ZX81 computers always failed with all the WRX games? My experience is more to the emulation side. That said, I recommend that you ask Simon to do some controlled tests (no RAM packs, Chroma interfaces etc - j...
by kpalser
Fri Jan 17, 2020 11:25 pm
Forum: GAMES
Topic: Cassette60 : the 1K hires games
Replies: 9
Views: 2012

Re: Cassette60 : the 1K hires games

Internal RAM or ULA, I don’t know. OK, so let’s narrow this down a bit: 1) Were the problems limited to WRX games? 2) Did any of the WRX games work on Simon’s ZX81? 3) Did Simon record any video or stills of the display problems? 4) Are there known cases where it works on one unmodified ZX81 withou...
by kpalser
Fri Jan 17, 2020 10:47 pm
Forum: GAMES
Topic: Cassette60 : the 1K hires games
Replies: 9
Views: 2012

Re: Cassette60 : the 1K hires games

Any conclusions why they don’t work on all ZX81s? The obvious being RAM packs or modified units with internal RAM not being compatible with WRX - but I think Simon ruled this out.
by kpalser
Tue Nov 19, 2019 11:29 pm
Forum: Emulators
Topic: Eightyone and Joystick controls.
Replies: 3
Views: 1478

Re: Eightyone and Joystick controls.

can you port it to android? Whilst I have written a couple native Android apps in the past, my limited free time would be the enemy here. It’s written in a platform technology optimised way to make the best of the Apple interface approach. Hence, it would be a mission to migrate to a solid maintain...
by kpalser
Tue Nov 19, 2019 9:42 pm
Forum: Emulators
Topic: Eightyone and Joystick controls.
Replies: 3
Views: 1478

Re: Eightyone and Joystick controls.

I doubt development will stop any time soon on EightyOne. However, it’s long overdue being ported from Borland Builder to another development environment to future proof ... well, its future. Hopefully when Paul is back online and settled from his move he can tweak it for you. In the meantime, if yo...