Search found 1262 matches

by troed
Wed Jan 17, 2018 8:30 pm
Forum: Hardware
Topic: BAD DMA - Myth or fact ?
Replies: 82
Views: 25287

Re: BAD DMA - Myth or fact ?

I have two 68HC000 laying around for when I would find some use for them. I'll happily do the same. Since they do seem to solve the famous DMA-issue it would probably well worth the time :)
by troed
Sun Jan 14, 2018 3:24 pm
Forum: Games - General
Topic: Enchanted Land parallax scroll
Replies: 5
Views: 418

Re: Enchanted Land parallax scroll

I never quite understood sync scroller. Hopefully (?) my little chapter on the subject in the Breakin' the Borders book helps a few more to understand how it works, even though I was pressed for space :) Mostly what was important for Enchanted Lands was that the following scanlines were non fullscr...
by troed
Sat Jan 13, 2018 11:42 pm
Forum: Hardware
Topic: LA traces on interesting video signals
Replies: 27
Views: 853

Re: LA traces on interesting video signals

Not sure why you need to sync it with Reset. As far as I can see, as long as you perform the pulse while Reset is asserted, it should work. That is, TEST high together with RESET low, triggers the counter reset. It might be that my Mega ST due to age is having difficulties keeping RESET asserted wh...
by troed
Sat Jan 13, 2018 9:17 pm
Forum: Hardware
Topic: LA traces on interesting video signals
Replies: 27
Views: 853

Re: LA traces on interesting video signals

I'll ponder about how to build such a WS cycling circuit. EDIT: Scrap the below. It WORKS. It does seem as if I need to time it to actual RESET very accurately though. I'm not sure why? Congratulations Ijor - yet another feather in your hat! :D On one single power cycle and three RESETs I've gone t...
by troed
Fri Jan 12, 2018 5:50 pm
Forum: Games - General
Topic: Enchanted Land parallax scroll
Replies: 5
Views: 418

Re: Enchanted Land parallax scroll

Also it works in all wakestates. Isn't that unusual for 1990? Are they just using a very conservative sync scroll that works every time? I don't think they knew how to detect all four wakestates in 1990? It's _very_ conservative. It needs 20 scanlines, and uses only right overscan, right+left overs...
by troed
Fri Jan 12, 2018 12:47 pm
Forum: Hardware
Topic: STFM to DVI/HDMI project
Replies: 78
Views: 4263

Re: STFM to DVI/HDMI project

Yeah it does sound strange. However, while the Mega ST schematics are from 1986, you can find the part number also in the Mega STE service manual from 1991: U17 C025914 IC CUSTOM SHIFTER U31 or C101608 IC CUSTOM FULL SHIFTER (w/D/A) U31 STF (Non STE) parts on Mega STE service manual ??? Where do yo...
by troed
Fri Jan 12, 2018 12:24 pm
Forum: Hardware
Topic: STFM to DVI/HDMI project
Replies: 78
Views: 4263

Re: STFM to DVI/HDMI project

Apparently there are three different Shifters, with slightly different motherboards, looking at the Mega ST schematics at least. One of the Shifter models does not output 3 bits RGB each, but has an internal version of the resistor grid and outputs the analog R,G,B signals directly. C101608 would b...
by troed
Thu Jan 11, 2018 10:38 pm
Forum: Hardware
Topic: STFM to DVI/HDMI project
Replies: 78
Views: 4263

Re: STFM to DVI/HDMI project

Regarding that, it's also a possibility to do so, but I initially envisaged this method being simpler. I think that I was wrong about that, and so I might try to make a board that reads the RGB values from the shifter's pins and leaves the shifter in place (this will work better on STE too). But ri...
by troed
Mon Jan 08, 2018 10:55 pm
Forum: Hardware
Topic: LA traces on interesting video signals
Replies: 27
Views: 853

Re: LA traces on interesting video signals

I think that at least in some computers, the 32 MHz is not a reliable direct clocking source. I might be in luck. The attached trace is of WS2 with the LA clocked using the 32MHz source. I've briefly looked at it and the resolution does seem to have been increased - the LOAD pulses are 5 32MHz cloc...
by troed
Mon Jan 08, 2018 6:16 pm
Forum: Hardware
Topic: LA traces on interesting video signals
Replies: 27
Views: 853

Re: LA traces on interesting video signals

It could be also half, or one an a half cycle. That is, one or more 32 MHz cycles. What I meant is that depending on the Shifter WS, the RGB timing could be different than the one seen at the traces. Well the B2 trace is of the output blue bit 2 so any Shifter wakeup should be visible there? (Come ...
by troed
Mon Jan 08, 2018 5:19 pm
Forum: Hardware
Topic: LA traces on interesting video signals
Replies: 27
Views: 853

Re: LA traces on interesting video signals

Well, as I commented some time ago in other thread, it is possible (at least in theory) to build a small circuit to force a specific wakestate without even power cycling. But you need somehow to intercept GLUE TEST pin. Interesting. Looking at the PIN schematics at https://www.exxoshost.co.uk/forum...
by troed
Mon Jan 08, 2018 3:01 pm
Forum: Hardware
Topic: LA traces on interesting video signals
Replies: 27
Views: 853

Re: LA traces on interesting video signals

Sync capture is great. But if you can and you still get one full frame, try using the 16MHz clock instead. Actually if you can combine RLE compression with sync clocking, then the clock frequency shouldn't reduce the amount of samples too much if at all. I thought I had tried that and decided 16MHz...
by troed
Sun Jan 07, 2018 10:57 pm
Forum: For sale / Wanted
Topic: For Sale: CT60e with Rev6 68060
Replies: 4
Views: 246

Re: For Sale: CT60e with Rev6 68060

Yes please, I'll take it.

Details in PM :)
by troed
Sun Jan 07, 2018 8:51 pm
Forum: Hardware
Topic: LA traces on interesting video signals
Replies: 27
Views: 853

Re: LA traces on interesting video signals

So I was going to post new captures but just saw that I managed to lose DE for some reason. Anyway, for the cases where only relation to CPU clock is of interest I've now managed to clock my LA from the CPU clock, which means I can stream all other signals at 50MHz and capture as many frames as I wa...
by troed
Sun Jan 07, 2018 5:58 pm
Forum: Hardware
Topic: I borked my 520ST Help?!?
Replies: 13
Views: 537

Re: I borked my 520ST Help?!?

Well, new DMA chip here, no go. Still boots to a white screen with a border, about 20 or 21 dark vertical lines evenly spaced across the screen. Searching around suggests RAM is the most likely candidate. Seems painful to desolder/ replace em all. Any suggestions on how to narrow it down? If you ha...
by troed
Sun Jan 07, 2018 10:47 am
Forum: 680x0
Topic: Boot sector and memory crushing
Replies: 19
Views: 764

Re: Boot sector and memory crushing

IIRC it's definitely usable. $4C6 points to the buffer address where the boot sector will be loaded. I think, it's been some years since I believe I used it ...

(Not sure what for though :))
by troed
Sat Jan 06, 2018 6:05 pm
Forum: 680x0
Topic: How NOT to set supervisor mode!
Replies: 11
Views: 486

Re: How NOT to set supervisor mode!

I must confess I've never tried setting the SSP through the supervisor trap. If you want to change the SSP when in supervisor mode it's really simple ;) move.l #stack,sp pea 0 move.w #$20,-(a7) trap #1 addq.l #6,a7 move.l d0,_save_usp+2 move.l _memtop,a0 suba.l #$1000,a0 move.l a0,a7 * set up stack ...
by troed
Sat Jan 06, 2018 5:56 pm
Forum: Hardware
Topic: LA traces on interesting video signals
Replies: 27
Views: 853

Re: LA traces on interesting video signals

Not sure if that would help, but there is no need to capture both clocks, certainly not for the whole frame. Btw, I moved your old posts with traces to this topic. Yeah I tried skipping 16MHz but (strangely, I thought) it didn't help much. I'm going to see what advanced modes there are to help out ...
by troed
Sat Jan 06, 2018 4:04 pm
Forum: Hardware
Topic: LA traces on interesting video signals
Replies: 27
Views: 853

Re: LA traces on interesting video signals

Which one do you mean by "this" revision? C025914? There the external diodes simply blank the output signals by pulling them down. Ah. The scan of the old schematics is simply of such low quality that I didn't see the crossed lines as being connected :) Thanks for the links - I remember n...
by troed
Sat Jan 06, 2018 3:43 pm
Forum: Hardware
Topic: LA traces on interesting video signals
Replies: 27
Views: 853

Re: LA traces on interesting video signals

Trivia: In the Mega ST schematics by Atari from 1986, there are three different Video out circuits detailed. 1) PIN C101608 FULL CUSTOM W/. D TO A CONVERTER 2) PIN C070713 FULL CUSTOM W/O D TO A CONVERTER 3) PIN C025914 GATE ARRAY W/O D TO A CONVERTER For cases 1 & 2 - BLANK is connected to pin ...
by troed
Sat Jan 06, 2018 2:50 pm
Forum: Hardware
Topic: LA traces on interesting video signals
Replies: 27
Views: 853

Re: LA traces on interesting video signals

Unfortunately it seems the built in RLE compression of the LA won't help out in this case since the signals change state too often. I'm only able to acquire ~51000-56000 samples at 100MHz, and anything lower won't accurately reflect the 8 and 16MHz cycles. New captures made, in WS2 and at 100MHz. No...
by troed
Sat Jan 06, 2018 1:28 pm
Forum: Coding
Topic: ST Chipset decap
Replies: 125
Views: 22368

Re: ST Chipset decap

My captures are going to be posted to this thread instead since they might capture things of interested to different projects, not just Shifter: viewtopic.php?f=15&t=32918

(IMP Shifters are on their way by post atm)
by troed
Sat Jan 06, 2018 1:20 pm
Forum: Hardware
Topic: LA traces on interesting video signals
Replies: 27
Views: 853

Re: LA traces on interesting video signals

Attached are traces from a regular low resolution screen where border color is #000 and the whole screen is filled with #777 graphics. I.e, blue bit 2 will be set when graphics are displayed, otherwise not. Also attached is exactly the same, but with a {Closure} fullscreen line. Both of these were m...
by troed
Sat Jan 06, 2018 1:19 pm
Forum: Hardware
Topic: LA traces on interesting video signals
Replies: 27
Views: 853

LA traces on interesting video signals

Posting as a new topic since some of these will be important to different concurrent projects. Feel free to suggest signals and methodology. I'm currently using my Mega ST with a non-IMP Shifter. An IMP Shifter has been ordered and I will trace it as well. I've currently hooked up 8 signals: /LOAD, ...
by troed
Sat Jan 06, 2018 9:54 am
Forum: Applications
Topic: TOS 3.1 desktop for the ST
Replies: 22
Views: 1140

Re: TOS 3.1 desktop for the ST

I never had a TT back in the day and had no official 3.x to compare to, but the reason we ran a software "TOS 3" was indeed that it offered more features. It's been "a few" years but I would expect it to have been something visible. Filled window movement, icons etc. I'm also sur...

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