Search found 451 matches

by Dio
Wed Aug 21, 2013 4:24 pm
Forum: Coding
Topic: horizontal scrolling on ST
Replies: 576
Views: 188891

Re: horizontal scrolling on ST

One thing is the DE signal but another will be the Shifter updating the RGB signals or not. I can test this (I am monitoring the RGB pins) if there is data in the first word of the 160-byte line. However, so far I see no indication that the 4th LOAD to visible signal has a variation, certainly not ...
by Dio
Wed Aug 21, 2013 3:49 pm
Forum: Coding
Topic: horizontal scrolling on ST
Replies: 576
Views: 188891

Re: horizontal scrolling on ST

Managed to kick it into other wakeup states with rapid power cycling. Looking only at normal 50Hz lines, I can't see any changes in timing apart from the DE to LOAD latency. HSYNC to DE, for example, is the same. This implies that the different wait states have different visible screen positions due...
by Dio
Wed Aug 21, 2013 3:22 pm
Forum: Coding
Topic: horizontal scrolling on ST
Replies: 576
Views: 188891

Re: horizontal scrolling on ST

Isn't the NTSC 160 offset by -4 compared to the PAL 160...? The answer is, for my machine, yes for WS2, WS3 and WS4 and no for WS1. A 162 bytes line (start like NTSC and end like normal PAL) will be shifted 4 pixels to the left for all WS except WS1. Now, if really show a NTSC line with the with th...
by Dio
Wed Aug 21, 2013 12:34 pm
Forum: Coding
Topic: horizontal scrolling on ST
Replies: 576
Views: 188891

Re: horizontal scrolling on ST

Isn't the NTSC 160 offset by -4 compared to the PAL 160...?
by Dio
Tue Aug 20, 2013 6:22 pm
Forum: Coding
Topic: horizontal scrolling on ST
Replies: 576
Views: 188891

Re: horizontal scrolling on ST

OK, I ran all Paulo's line lengths (but not the funny modes yet) on my ST in WS1 (which is 6 cycles DE to LOAD latency and the one my machine seems to be very nearly stuck in at the moment) and captured some traces. I've dozens of PNGs that I won't post yet, but a few interesting things are revealed...
by Dio
Mon Aug 19, 2013 9:26 pm
Forum: Coding
Topic: horizontal scrolling on ST
Replies: 576
Views: 188891

Re: horizontal scrolling on ST

It's fine for HW reg writes, I assume that everyone does it that way. It's as soon as you have to apply it to system memory it's a problem. You have to snoop every memory write and compare with the screen location before deciding if you need to render afterwards. That said, at 8MHz on anything resem...
by Dio
Sat Aug 17, 2013 8:44 am
Forum: Coding
Topic: horizontal scrolling on ST
Replies: 576
Views: 188891

Re: horizontal scrolling on ST

(It seems my Shifter is a slow warmer Is there research to demonstrate that it's specifically the shifter (e.g. by freeze spray)? If not, we should use 'system' instead of 'shifter' to avoid introducing imperfect terminology. I think Paolo has already shown some evidence there are multiple warming ...
by Dio
Wed Aug 14, 2013 9:58 am
Forum: Coding
Topic: Setting up the BITBLT struct for LINEA
Replies: 30
Views: 7547

Re: Setting up the BITBLT struct for LINEA

I don't remember the reason for this, if there ever was a good one. Perhaps they calculated linea ops are a bit quicker for graphics than trap calls because they don't need a function argument. Denser code, since the param is implicit. Slower, though, because the called code needs to go fetch the s...
by Dio
Tue Aug 13, 2013 7:15 pm
Forum: Coding
Topic: horizontal scrolling on ST
Replies: 576
Views: 188891

Re: horizontal scrolling on ST

One thing to think about is that one or more of the ff8260 changes may be taking place at a different time in the Glue and in the Shifter, since it's two different devices mirroring the same state. In particular, the Shifter only sees the write through the bus gateway, which may (is likely to?) impo...
by Dio
Tue Aug 13, 2013 7:10 am
Forum: Coding
Topic: horizontal scrolling on ST
Replies: 576
Views: 188891

Re: horizontal scrolling on ST

With my machine, I also find that glitching the power quickly is the most likely thing to force a change in wakeup state. It seems to pick all of them fairly randomly though, that may be because I just have the motherboard bare on the table :) .
by Dio
Sun Aug 11, 2013 10:08 pm
Forum: Coding
Topic: horizontal scrolling on ST
Replies: 576
Views: 188891

Re: horizontal scrolling on ST

Realistically, anything which interferes with either the colour burst or the sync timings is illegal always; if you do want to widen the window to allow that sort of thing, then the only thing you should be testing on is a CRT with good old fashioned analogue decoding. That any antique computer work...
by Dio
Sat Aug 10, 2013 12:14 pm
Forum: Coding
Topic: horizontal scrolling on ST
Replies: 576
Views: 188891

Re: horizontal scrolling on ST

Just to clarify, when you say 'rev C' do you mean C070523-001 Rev C? I think C070789 may have a Rev C too and possibly some others of the later boards. My initial testing will be on a C070523 Rev D STFM (an early one). I also have a slightly later (judging by the date and a few minor component tweak...
by Dio
Fri Aug 09, 2013 8:25 pm
Forum: Coding
Topic: horizontal scrolling on ST
Replies: 576
Views: 188891

Re: horizontal scrolling on ST

Brilliant. I got all the ST stuff out of the garage last night and I've captured a few traces tonight to make sure everything' running OK. I'll take a look at this over the weekend. That things change over time is almost certainly some transition being very close to the point at which it's checked a...
by Dio
Fri Aug 09, 2013 9:05 am
Forum: Coding
Topic: horizontal scrolling on ST
Replies: 576
Views: 188891

Re: horizontal scrolling on ST

You said you would prefer that the SW uses a less as possible the A23 which means as less changes to $FFFF820A/60 as possible. Some of the lines sizes available are not stable with the minimum sync/resol switches: if you use them once it might work but if you repeat their use, like 2, 3, 4, ... the...
by Dio
Thu Aug 08, 2013 7:32 am
Forum: Coding
Topic: horizontal scrolling on ST
Replies: 576
Views: 188891

Re: horizontal scrolling on ST

Whenever it's done is fine, my interest is currently piqued and I've tidied the office enough to get all the bits out of the garage :) . One line per frame, with the shifter reset at VSYNC, is ideal. Doesn't really matter what line it's on. I just need an easy triggering condition. I was going to lo...
by Dio
Wed Aug 07, 2013 9:00 pm
Forum: Coding
Topic: horizontal scrolling on ST
Replies: 576
Views: 188891

Re: horizontal scrolling on ST

At the moment, i can have for all 4 wake up states the following line lengths for which i can later on provide SW for you to test: One thing worth doing is during the test make sure the colour output conveys some useful information: if I capture one bit each of RGB then there's 8 different states t...
by Dio
Wed Aug 07, 2013 4:56 pm
Forum: Coding
Topic: horizontal scrolling on ST
Replies: 576
Views: 188891

Re: horizontal scrolling on ST

If someone else has written the software, I'll gladly not do it myself :) . I was wrong to think a 2-byte line is possible. It's the 162-byte line I was thinking of. I'll look at defining a set of 16 signals that I can capture for each of these cases which will provide us with useful data to conside...
by Dio
Wed Aug 07, 2013 3:20 pm
Forum: Coding
Topic: horizontal scrolling on ST
Replies: 576
Views: 188891

Re: horizontal scrolling on ST

Wake-up states aren't relevant to the 158-byte case though - it just works on all STs (even the STE I think). The one thing I do know is that the minimum DE to LOAD latency is 3 CPU clock cycles (since the four wake up states have latencies of 3, 4, 5 and 6 between DE and the first LOAD). I measured...
by Dio
Wed Aug 07, 2013 12:56 pm
Forum: Coding
Topic: horizontal scrolling on ST
Replies: 576
Views: 188891

Re: horizontal scrolling on ST

I know some of the people working on VHDL have done it by side-by-side-ing with an existing chip and verifying the exact same signals come out of the FPGA as the original chip when presented with the same inputs. But I agree that even if that's the R&D technique there's no guarantee that all the int...
by Dio
Wed Aug 07, 2013 11:44 am
Forum: Coding
Topic: horizontal scrolling on ST
Replies: 576
Views: 188891

Re: horizontal scrolling on ST

1- The GLUE detects 60 Hz at the end of the timing of the NTSC screen, and disables the DE signal 4 CPU cycles early; I assume this is the case; I can show this one on the logic analyser. 2- The Shifter is expecting a 4th word from the MMU to build the last 16 pixels of the line but that word does ...
by Dio
Wed Aug 07, 2013 7:39 am
Forum: Coding
Topic: horizontal scrolling on ST
Replies: 576
Views: 188891

Re: horizontal scrolling on ST

I'm not so concerned about its use as a stabiliser, just the case where it's used to remove the lower border with (as I thought) no sideeffects. I'm looking for the very simplest cases to investigate here :) .
by Dio
Tue Aug 06, 2013 3:48 pm
Forum: Coding
Topic: horizontal scrolling on ST
Replies: 576
Views: 188891

Re: horizontal scrolling on ST

Thanks. I shall muse on this.
by Dio
Tue Aug 06, 2013 3:11 pm
Forum: Coding
Topic: horizontal scrolling on ST
Replies: 576
Views: 188891

Re: horizontal scrolling on ST

OK, thanks for the update. I'm not entirely clear what you're describing here. On what line is the 158-byte line? And you say it does wrap around to the top of the screen? Raises more interesting questions. If that's the case, are demos that use the 158-byte line case to open the lower border (e.g. ...
by Dio
Tue Aug 06, 2013 11:40 am
Forum: Coding
Topic: horizontal scrolling on ST
Replies: 576
Views: 188891

Re: horizontal scrolling on ST

Not at all. Next time I have the logic analyser on the ST I'll use your program and verify that the four wake up states correspond to the four different DE to screen start latencies that I observed last time I was investigating this issue. I'm not certain there can be discrepancies because of the hi...
by Dio
Sun Aug 04, 2013 4:01 pm
Forum: Games - General
Topic: Graphics and Map ripping from Atari ST games
Replies: 29
Views: 8696

Re: Graphics and Map ripping from Atari ST games

There's a very few things which are extremely hard to emulate - notably, the timing of IO that goes outside the target. Input in particular is really tricky - it tends to arrive in clumps unless you have lots of control over host time (which you can't, really, on a multitasking OS). Beyond that, tho...

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