Search found 54 matches
- Sun Apr 28, 2013 12:11 am
- Forum: Hardware
- Topic: Simple Video Mod for 210ULA
- Replies: 19
- Views: 19249
Re: Simple Video Mod for 210ULA
Thanks for the pictures. It looks good so far. As the transistor solution this is what most people do for a simple discoupling of the video signal (in fact without the two diodes). It could be a good idea to put a second smaller resistor (47R for example) between +5V and collector to protect the tr...
- Sun Apr 28, 2013 12:08 am
- Forum: Development
- Topic: ZX81 Nixie Clock Source code
- Replies: 2
- Views: 2828
Re: ZX81 Nixie Clock Source code
Hi PokeMon, Thanks for having a look at the code. >>>Well took a look at your source but it's a bit complicate. Just three suggestions from my side: 1. You can use the variables section (printer buffer) directly when you include ZX81VARS.INC (and ZX81DEF.INC) instead of simply ZX81.INC Then you can ...
- Sat Apr 27, 2013 6:57 am
- Forum: Development
- Topic: ZX81 Nixie Clock Source code
- Replies: 2
- Views: 2828
ZX81 Nixie Clock Source code
In this thread discussions about the ZX81 Nixie Clock source code. It is open source, so everyone can have a look at it and make modifications where possible. Would be nice to have a DCF77 interface connected to it, as found in the German forum. It wouldn't be of any help to me as we can't receive t...
- Sat Apr 27, 2013 6:33 am
- Forum: Development
- Topic: Read keyboard from assembly
- Replies: 16
- Views: 10673
Re: Read keyboard from assembly
We are not talking about 65 bytes. In a 1k program you have about 750-800 bytes free for an assembly program (with small BASIC start statement like 10 REM .... and 20 RAND USR ...) with a collapsed display file which is nearly empty. In your video you only print time in the first screen line, so di...
- Sat Apr 27, 2013 5:01 am
- Forum: Hardware
- Topic: Simple Video Mod for 210ULA
- Replies: 19
- Views: 19249
Re: Simple Video Mod for 210ULA
OK, I didn't expect to spend this much time on it but there are enough arguments to do a further investigation :-). First of all, the drawn current from ULA pin 16. I measured this compared to another TS1000 that still has the pin 16 connected to the RF modulator. In fact, the RF modulator draws a H...
- Sat Apr 27, 2013 12:12 am
- Forum: Development
- Topic: Read keyboard from assembly
- Replies: 16
- Views: 10673
Re: Read keyboard from assembly
I wanted to use the keyboard to set the time for my clock (using 0 - 9, and some letters for setting hours, minutes etc). However, while programming this, I realized the program was never going to fit within 1k no more so I abandoned the idea and went for a simple basic solution (INPUT A$) and read...
- Fri Apr 26, 2013 11:51 pm
- Forum: Hardware
- Topic: Simple Video Mod for 210ULA
- Replies: 19
- Views: 19249
Re: Simple Video Mod for 210ULA
Can not see in your scope pictures very good but I think the same reason gozzo meant here. The white level voltage from ULA breaks down due to a low impedance connected. This moves the adapted signal in a way with not much white level. The ULA normally puts out a range of up to 5V which is modulate...
- Fri Apr 26, 2013 2:17 pm
- Forum: Development
- Topic: Read keyboard from assembly
- Replies: 16
- Views: 10673
Re: Read keyboard from assembly
btw. shouldn't this post be in another section/subforum? Yes, it should be moved to the Development section. I wonder if the simply reading in a game via IN instruction doesn't result in screen flickering as the line counter should be reset by IN ($FE) and this process is not synchronized. :shock: ...
- Fri Apr 26, 2013 12:15 pm
- Forum: Hardware
- Topic: Simple Video Mod for 210ULA
- Replies: 19
- Views: 19249
Re: Simple Video Mod for 210ULA
Not using a buffer could be the reason why you had a dark picture , the video input of your TV was loading the ULA's output too much, if it was buffered with an emitter follower OR a video op-amp/buffer I've come across, the AD817AN , (not yet tried it, though), it would probably be ok. Not so, the...
- Fri Apr 26, 2013 11:41 am
- Forum: Hardware
- Topic: Simple Video Mod for 210ULA
- Replies: 19
- Views: 19249
Re: Simple Video Mod for 210ULA
Even simpler if you leave the modulators innards there, no need to remove them. However I don't really like the idea of not buffering the video, and isolating it with a capacitor, but if it seems to work ok and the ULA isn't being overloaded, then its great ! I didn't think about that as I had firs...