Search found 17 matches

by mikeb
Fri Jan 04, 2019 6:30 pm
Forum: Hardware hacks and extensions
Topic: Cumana Disk Controller PCB
Replies: 2
Views: 109

Re: Cumana Disk Controller PCB

The Cumana ROM (personally dumped from my own unit) seems to be 8K ... -r--r--r-- 1 root root 8.0K Oct 6 2010 Data/EPROM Images/OwnedStandard/cumana11.rom And this dumped from a chip loaned by Steve Marshall ... -r--r--r-- 1 root root 8.0K Oct 6 2010 Data/EPROM Images/Downloaded/Steve Marshall Loane...
by mikeb
Tue Dec 04, 2018 6:42 pm
Forum: Demos
Topic: OricExos - making the impossible
Replies: 82
Views: 7102

Re: OricExos - making the impossible

It is a bit surprising that nobody in this community started such a project, or even a core for those already working on FPGAs... but that is another matter. I know for a fact that someone did do a VHDL ULA model, I came across it while looking for ULA related material. It was dated some time after...
by mikeb
Mon Dec 03, 2018 6:11 pm
Forum: Demos
Topic: OricExos - making the impossible
Replies: 82
Views: 7102

Re: OricExos - making the impossible

iss wrote:
Sun Dec 02, 2018 9:14 pm
without buffer on the parallel port
when all VIAs start to write together to their AY then there will be smoke :?.
Reminds me of this magazine :)

Image
by mikeb
Sat Nov 10, 2018 6:32 pm
Forum: Demos
Topic: OricExos - making the impossible
Replies: 82
Views: 7102

Re: OricExos - making the impossible

Definitely getting a better balance on the weighting of the colours in the new colour bars video! Keep going :) On the video output card, that AD(unreadable) surface mount chip makes me think of this for some reason ... https://pmcvariety.files.wordpress.com/2013/11/volvo-jean-claude-van-dam.jpg?w=1...
by mikeb
Thu Oct 25, 2018 5:40 pm
Forum: Demos
Topic: OricExos - making the impossible
Replies: 82
Views: 7102

Re: OricExos - making the impossible

what can be done about attribute clash in this configuration .. like, if it can be exploited somehow, actually .. Think about using even-odd operation based on the column number: While one Oric is emitting PAPER colour (because that byte is an attribute), the other one can be emitting a character/r...
by mikeb
Fri Oct 12, 2018 4:51 pm
Forum: Demos
Topic: OricExos - making the impossible
Replies: 82
Views: 7102

Re: OricExos - making the impossible

... internal 200 Ohms resistors - I hooked RGB signals AFTER them, so they play their role in the 'equation' and the output is (as I already said) OR-ed but not exactly - it's analogue circuit already. Well, all digital circuits are analogue underneath, and all analogue circuits move whole electron...
by mikeb
Thu Oct 11, 2018 5:29 pm
Forum: Demos
Topic: OricExos - making the impossible
Replies: 82
Views: 7102

Re: OricExos - making the impossible

@Dbug: it's really weird - if 2 Orics output white then the 3rd become invisible no matter which color it displays It's not weird -- it's logical. Literally :) 1 or 1 = 1 ... although you do seem to have a third state of "almost one" in the colour bars, (0, almost 1, very much 1). The voltages won'...
by mikeb
Sun Sep 16, 2018 9:04 pm
Forum: Technical questions
Topic: Merging video output?
Replies: 86
Views: 29506

Re: Merging video output?

Thanks, mikeb, your math is correct :). I only mean the simplest case - without any additional resistors, simply short connected R, G and B outputs on SK2. BTW, can you do the R-values math for 4 Oric's? :roll: It's not my maths, those resistor figures were from Oric Owner, but it's my explanation,...
by mikeb
Sat Sep 15, 2018 7:45 pm
Forum: Technical questions
Topic: Merging video output?
Replies: 86
Views: 29506

Re: Merging video output?

There is one small detail related to the direct video mixing - RGB outputs are not TTL levels but the signal goes through resistors 200 Ohms. The result is absolutely similar to the internal audio channel mixing discussed in Oric's 8912 volume scale . But this actually will lead to nice effects :)....
by mikeb
Thu Sep 13, 2018 6:12 pm
Forum: Technical questions
Topic: Merging video output?
Replies: 86
Views: 29506

Re: Merging video output?

Double buffering and top-bottom splits are all possible. (Or splitting by odd-even columns, allowing one ULA to set an attribute, while the other is displaying a character, allowing the colour changes to get closer together). No more "leaving a blank space" for an attribute? - We also would like to ...
by mikeb
Thu Sep 13, 2018 5:58 pm
Forum: General Discussion
Topic: California Devices Inc and the HCS10017
Replies: 31
Views: 4755

Re: California Devices Inc and the HCS10017

OK, if anybody finds C19, I want it back! That really could be the difference -- the lack of decoupling capacitor across the rails close to the chip allows the voltage on the d6 databus/pins to spike nastily when the other ICs are better behaved. It does say "additional signals", meaning noise. Nice...
by mikeb
Wed Sep 12, 2018 9:41 pm
Forum: Technical questions
Topic: Merging video output?
Replies: 86
Views: 29506

Re: Merging video output?

@iss excellent news -- your circuit (posted) covers basically what I described regarding diodes to isolate the "R" outputs (p19) from each other, and to also kick the processor into reset, just to be sure. You were probably getting contact-bounce from the switch that was upsetting things. A clean re...
by mikeb
Wed Sep 12, 2018 9:20 pm
Forum: General Discussion
Topic: California Devices Inc and the HCS10017
Replies: 31
Views: 4755

Re: California Devices Inc and the HCS10017

@symoon Congratulations Mike, and to all those involved. Thanks very much. Did you mean congrat ULA tions ? :lol: @iss - I am so annoyed at myself for not seeing that. All these years staring at that circuit for different reasons, and even after everything written in that PDF, I didn't even notice t...
by mikeb
Sat Sep 08, 2018 9:12 pm
Forum: General Discussion
Topic: California Devices Inc and the HCS10017
Replies: 31
Views: 4755

Re: California Devices Inc and the HCS10017

Back to the ULA document: Can anyone with a long memory, or the right early documentation, let me know if ever there was a time, early in the history of Oric where the INK and PAPER colours were not as we know them now ? I'm thinking early as in pre-production/prototype models. Is there any evidence...
by mikeb
Sat Sep 08, 2018 10:53 am
Forum: General Discussion
Topic: California Devices Inc and the HCS10017
Replies: 31
Views: 4755

Re: California Devices Inc and the HCS10017

DRAM is indeed much more persistent that the manufacturer datasheets imply. On the Amiga one can sometime get back enough valid memory even 10s after powering on the machine. This could explain why when I tried doing a reduced-hardware version of Steve Ciarcia's DRAM chip based camera from Byte mag...