Search found 167 matches

by Smonson
Sat Oct 27, 2018 9:55 am
Forum: HARDWARE DISCUSSIONS
Topic: BLITTER RE-CREATION THOUGHTS
Replies: 101
Views: 6577

Re: BLITTER RE-CREATION THOUGHTS

Problem is tri-state the buffers, when the FPGA goes tri-state, nothing is driving the buffers, so logic output to the bus will be "random"... The buffers need to be isolated, but there is no control for that. So I can't use "normal" buffers ICs.. only FET based ones which don't have tri-state issu...
by Smonson
Sat Oct 27, 2018 12:58 am
Forum: HARDWARE DISCUSSIONS
Topic: BLITTER RE-CREATION THOUGHTS
Replies: 101
Views: 6577

Re: BLITTER RE-CREATION THOUGHTS

Hi, sorry I haven't read the complete thread but I see you're looking for bidirectional 3.3 to 5v interface logic - the one I used for the data bus on the HDMI thing is 74ALVC164245DL,112. It has two groups of 8 pins with a direction control and tristate pin per group. They're about $2 each in x10 p...
by Smonson
Fri Oct 26, 2018 2:23 pm
Forum: HARDWARE DISCUSSIONS
Topic: Project: HDMI/DVI out for STFM
Replies: 262
Views: 16943

Re: Project: HDMI/DVI out for STFM

This is a comparison between the original (regular logic) buffer, and the clock fanout buffer at 16MHz. It's clear that the new one is a more forceful driver. The clock on the 68k pin is quite rounded still, I think 100 ohms in series is a bit on the high side to get any benefit from the squarer sig...
by Smonson
Fri Oct 26, 2018 10:35 am
Forum: HARDWARE DISCUSSIONS
Topic: Project: HDMI/DVI out for STFM
Replies: 262
Views: 16943

Re: Project: HDMI/DVI out for STFM

I would suggest putting resistors in there needed or not. can always zero ohm them if don't need them, but better to have that option. I generally add 33R in all clock ins and outs. I also use a schmitt buffer (tiny logic) for the actual buffering IC. About the extra "optional" resistor footprint: ...
by Smonson
Thu Oct 25, 2018 12:25 pm
Forum: HARDWARE DISCUSSIONS
Topic: Project: HDMI/DVI out for STFM
Replies: 262
Views: 16943

Re: Project: HDMI/DVI out for STFM

Small update regarding clocks. I "engineered" in an NB3N551 proper clock buffer in place of the generic logic buffer I had on the adapter board originally. Anyway, it worked fine first go and is rated up to 180MHz, so that should hopefully be totally future-proof. Many thanks to rpineau for suggesti...
by Smonson
Wed Oct 17, 2018 9:07 am
Forum: ELECTRONICS
Topic: Lead-free soldering
Replies: 22
Views: 448

Re: Lead-free soldering

I still use classic 60/40. Over here in Australia the more we can do to damage the environment, the more we like it!

Take that, groundwater table!
by Smonson
Thu Oct 04, 2018 3:01 pm
Forum: HARDWARE DISCUSSIONS
Topic: Project: HDMI/DVI out for STFM
Replies: 262
Views: 16943

Re: Project: HDMI/DVI out for STFM

I've seen the same effect on pretty much every pirated game, and as far as I know it works fine on HDMI. Spectrum 512 also uses the background colour to show bars, but it's a semi-static effect. I only use HDMI so I have no easy way to compare the two setups.
by Smonson
Thu Oct 04, 2018 11:18 am
Forum: HARDWARE DISCUSSIONS
Topic: Project: HDMI/DVI out for STFM
Replies: 262
Views: 16943

Re: Project: HDMI/DVI out for STFM

czietz wrote:
Thu Oct 04, 2018 10:48 am
For the screen border afaik always palette entry 0 is used, so you'll see whatever color is programmed into that entry.
Yeah, I think you're right. I have no theory to explain that behaviour.
by Smonson
Thu Oct 04, 2018 9:53 am
Forum: HARDWARE DISCUSSIONS
Topic: Project: HDMI/DVI out for STFM
Replies: 262
Views: 16943

Re: Project: HDMI/DVI out for STFM

I don't have a "default" palette in the FPGA shifter. Maybe there's a default palette in the real shifter, and you're seeing those colours. It's something I can add.
by Smonson
Thu Oct 04, 2018 2:26 am
Forum: HARDWARE DISCUSSIONS
Topic: Project: HDMI/DVI out for STFM
Replies: 262
Views: 16943

Re: Project: HDMI/DVI out for STFM

That's interesting. I'd like to know more about this. I take it this is a program that works with or from a diagnostic cartridge?