Search found 235 matches
- Wed Apr 12, 2023 10:39 pm
- Forum: Hardware and Tech
- Topic: FPGA 6561 - PAL Questions
- Replies: 25
- Views: 5041
Re: FPGA 6561 - PAL Questions
Well, I thought I'd use the VICE Vic-20 colour palette for NTSC - except I don't understand the encoding in the structure. Take the two colours, Cyan and Green. First, there are some defines: #define ANGLE_RED 112.5f #define ANGLE_GRN -112.5f #define ANGLE_BLU 0.0f #define ANGLE_ORN -45.0f Then the ...
- Tue Apr 11, 2023 7:46 pm
- Forum: Hardware and Tech
- Topic: FPGA 6561 - PAL Questions
- Replies: 25
- Views: 5041
Re: FPGA 6561 - PAL Questions
I have three 6560 chips - lovingly named "Red", "Green" and "Blue" - not because of any particular colour cast they have or anything like that, but because each one has a dot of that color stuck to it so I can identify them, for example, "Green" has a faulty r...
- Mon Apr 10, 2023 6:34 pm
- Forum: Hardware and Tech
- Topic: Vic 20 brightness fluctuating
- Replies: 6
- Views: 2394
Re: Vic 20 brightness fluctuating
Thanks for replying. I'm using an original power supply, I've not had any obvious problems with it so far, but it does sound similar to one or two problems in threads I've found on this forum. I noticed they power supplies are very expensive to replace on eBay :( Is there any ways to tell if the po...
- Mon Apr 10, 2023 5:56 pm
- Forum: Hardware and Tech
- Topic: FPGA 6561 - PAL Questions
- Replies: 25
- Views: 5041
Re: FPGA 6561 - PAL Questions
In theory all dark colours (2-8) should have roughly 2*L amplitude and all light colours (9-15) should have L amplitude, where L is the amplitude of the colour burst signal. But again this does not really work in practice. You're all going to hate my NTSC colour tables. Note that I am definitely no...
- Mon Apr 10, 2023 4:50 pm
- Forum: Hardware and Tech
- Topic: FPGA 6561 - PAL Questions
- Replies: 25
- Views: 5041
Re: FPGA 6561 - PAL Questions
On the 6561 a line is not 64µs, rather 4*71/fsc, where fsc is the colour burst frequency. So slightly above 64µs. It's only out by 0.09%, which if it were independent of everything else wouldn't be an issue in the slightest, I'm sure. How you avoid the carrier being in lock with the horizontal line...
- Sun Apr 09, 2023 9:49 pm
- Forum: Hardware and Tech
- Topic: FPGA 6561 - PAL Questions
- Replies: 25
- Views: 5041
FPGA 6561 - PAL Questions
I'm looking into what I must do to support PAL on the 6561 FPGA. I'm going to be assuming PAL G / I parameters for the video are: 25 frames/second 50 fields/second 625 scan lines/frame 312.5 scan lines/field 288/576 visible lines per field/frame .576ms vert sync length 4.43361875 MHz colour subcarri...
- Sun Apr 09, 2023 8:14 pm
- Forum: Hardware and Tech
- Topic: Vic 20 brightness fluctuating
- Replies: 6
- Views: 2394
Re: Vic 20 brightness fluctuating
I'd start by blaming the power supply. Are you using the original power supply from way back or a modern replacement?
- Wed Mar 29, 2023 4:24 pm
- Forum: Hardware and Tech
- Topic: An idea for a useless project
- Replies: 12
- Views: 3026
Re: An idea for a useless project
If you are going to use a VIC-2020, be aware that you need real, genuine ICs for the 74 series logic, not random re-labelled knock-offs, and of the right family (e.g. if the parts list calls for LS then do not try HCT etc.) - his timing is very tight, and "only the best will do".
- Wed Mar 29, 2023 4:19 pm
- Forum: Hardware and Tech
- Topic: Cartridge designs released - Eagle PCBs
- Replies: 40
- Views: 22109
Re: Cartridge designs released - Eagle PCBs
Also check with JLCPCB - they may be cheaper.
- Mon Mar 20, 2023 3:07 pm
- Forum: Hardware and Tech
- Topic: Video noise on VIC-20
- Replies: 51
- Views: 14220
Re: Video noise on VIC-20
This product bought through Amazon worked for me without interference - make sure you give it a good ground connection. This is either 110 or 240V compatible: https://www.amazon.com/gp/product/B005T6UJBU/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 And this is the 9V AC transformer I used ***...
- Sat Mar 18, 2023 10:43 am
- Forum: Hardware and Tech
- Topic: 6560 FPGA Progress.
- Replies: 152
- Views: 17322
Re: 6560 FPGA Progress.
Nice video. Thanks. Looking forward to future episodes... I should have made a video about the board I've been working on to interface with the new FPGA development board I'm switching to. It would involve such epic scenes as "why are their connectors numbered backwards? There is no physical w...
- Sat Mar 18, 2023 10:33 am
- Forum: Hardware and Tech
- Topic: 6560 FPGA Progress.
- Replies: 152
- Views: 17322
Re: 6560 FPGA Progress.
The VIC (6560/6561) in fact has sepearate luma resistors for each colour, see for example this thread (partly in German) https://www.forum64.de/index.php?thread/110862-helligkeiten-der-c64-pal-palette-zum-100-mal/&postID=1699320#post1699320 I guess in the world that is FPGAs, I can say, "f...
- Tue Mar 14, 2023 8:16 pm
- Forum: Hardware and Tech
- Topic: 6560 FPGA Progress.
- Replies: 152
- Views: 17322
Re: 6560 FPGA Progress.
History and technical info about what I've done so far: https://www.youtube.com/watch?v=fZqIlUJzN74
- Sun Mar 12, 2023 2:57 pm
- Forum: Hardware and Tech
- Topic: Video noise on VIC-20
- Replies: 51
- Views: 14220
Re: Video noise on VIC-20
It could be that noise from the 5V switched mode supply gets into the 9V AC output of the supply - however, the 9V side doesn't go anywhere interesting in the VIC-20, just to the user port and the cassette port (the same is not true of a C64, where it is used to generate a "clean" 5V suppl...
- Thu Mar 09, 2023 6:16 pm
- Forum: Hardware and Tech
- Topic: Video noise on VIC-20
- Replies: 51
- Views: 14220
Re: Video noise on VIC-20
Would a small plastic box with a 7-pin DIN socket on each end and a couple of capacitors and an inductor inside, with values picked to filter out this particular noise, be a useful "product" do you think? If we know the frequency, we can build a suitable filter to squash it. The problem is...