Search found 3125 matches

by ijor
Mon Apr 13, 2020 2:13 pm
Forum: Coding
Topic: Blitter Execution Times
Replies: 43
Views: 6726

Re: Blitter Execution Times

Hi Nicolas, looking at the verlilog code, I see that FXSR value is latched when writing to skew register, but not NFSR. Is there any reason for that ? (I guess that's the way original blitter was designed ?) Or is 'fxsrLatch' just a variable name to indicate the current FXSR value required for the m...
by ijor
Sat Apr 11, 2020 2:46 am
Forum: Coding
Topic: Blitter Execution Times
Replies: 43
Views: 6726

Re: Blitter Execution Times

If XCOUNT is set to one, Blitter doesn't fully honor the NFSR bit and performs a final source read regardless. Nicolas, I have also seen that you finally have reverted the second patch I provided you supposed to fix this Xcount=1/NFSR problem in Hatari, because it caused some regression with the 'O...
by ijor
Sat Apr 04, 2020 2:00 am
Forum: Coding
Topic: Blitter Execution Times
Replies: 43
Views: 6726

Re: Blitter Execution Times

Still, Atari's user manual for the blitter from 25 jan 1990 seems to be erroneous. See at the end of "functional description" on page 7 : Similarly the NFSR (aka post-flush) bit, when set, will prevent the last source read of the line. This read may not be necessary with certain combinations of end...
by ijor
Wed Apr 01, 2020 4:28 pm
Forum: Floppy Disk Preservation
Topic: Floppy Disk Stream Image Repository
Replies: 272
Views: 86211

Re: Floppy Disk Stream Image Repository

@ijor, are there many disks with data up to the 83rd track? (Is there a list anywhere?) I'm just curious if I have anything that might be on it. (So far only that one disk showed data after track 80. I would have dumped to track 82 previously) There are very few original disks with more than 80 tra...
by ijor
Wed Apr 01, 2020 3:12 am
Forum: Floppy Disk Preservation
Topic: Floppy Disk Stream Image Repository
Replies: 272
Views: 86211

Re: Floppy Disk Stream Image Repository

The datasheet for the drive said it's an 82 track drive. (It's a PC Drive: Alps DF354 H090F) That doesn't mean too much, as you find out yourself. OK, so, I tried 82, 83 and 84 tracks. They all seem to read, but when I checked the 84 track dump, there was no data in there, but it didn't look like t...
by ijor
Mon Mar 30, 2020 11:02 pm
Forum: Floppy Disk Preservation
Topic: Floppy Disk Stream Image Repository
Replies: 272
Views: 86211

Re: Floppy Disk Stream Image Repository

More: Running man seems to have data on tracks 81 and 82, which is rare. I've no idea if there's anything on tracks 83 and 84, but my drive said it's only an 82 track drive, so I didn't try them. These dumps have now been added. Running Man disks look fine. I don't believe any disk normally has dat...
by ijor
Fri Mar 27, 2020 6:30 pm
Forum: News & Announcements
Topic: New document at Atari Museum
Replies: 7
Views: 1362

Re: New document at Atari Museum

Hi Christian,
czietz wrote:Interesting. You might remember that I deduced/guessed that the first ASICs for the ST (the -20 models) were from Universal Semiconductor.
I do, and I did remember first time I read the document :)
by ijor
Fri Mar 27, 2020 6:29 pm
Forum: 680x0
Topic: pea versus move.l to the stack
Replies: 12
Views: 1290

Re: pea versus move.l to the stack

lp wrote:In my cause I'm using move.l a0,-(sp) to push a pointer.
MOVE.l A0,-(SP) & PEA (A0) are essentially the same and take the same number of cycles.
The main difference, again, is that MOVE affects the flags but PEA does not.
by ijor
Fri Mar 27, 2020 3:42 pm
Forum: 680x0
Topic: pea versus move.l to the stack
Replies: 12
Views: 1290

Re: pea versus move.l to the stack

MOVE.L #XXX,-(SP) and PEA ABS.L take exactly the same number of cycles.
MOVE.L Dn,-(SP), if suitable, is obviously faster.
Depending on the case you might be able to use shorter (and faster) PEA addressing modes, such as PEA (XXX).W

PEA doesn't affect the flags, MOVE.L does.
by ijor
Fri Mar 27, 2020 12:54 pm
Forum: News & Announcements
Topic: New document at Atari Museum
Replies: 7
Views: 1362

New document at Atari Museum

Curt Vendel released a a couple of new internal memo Atari 1984 documents. They mostly cover the 8-bit family but there are a couple of interesting notes about the ST. This is the web page: http://www.atarimuseum.com/computers/8BITS/XE/xesystems.html This is the relevant document: http://www.atarimu...
by ijor
Mon Mar 23, 2020 5:29 am
Forum: MiSTer
Topic: FX CAST Atari ST core
Replies: 336
Views: 159440

Re: FX CAST Atari ST core

telengard wrote:The core defaults to PAL on my 15Khz and I can't change it. :lol:
15 KHz is currently not supported. VGA output is always scan doubled. It will be supported shortly, but not yet. Sorry.
by ijor
Sun Mar 22, 2020 2:51 pm
Forum: Floppy Disk Preservation
Topic: Floppy Disk Stream Image Repository
Replies: 272
Views: 86211

Re: Floppy Disk Stream Image Repository

Strange that you don't have to disable drive B when the .scp is used though. The environment is different. Steem using its own FDC emulation for SCP files, but it uses Pasti for STX images. It's a buglet in Steem's FDC emulation that doesn't behave exactly like real hardware. Which Steem version ar...
by ijor
Sun Mar 22, 2020 12:27 pm
Forum: Floppy Disk Preservation
Topic: Floppy Disk Stream Image Repository
Replies: 272
Views: 86211

Re: Floppy Disk Stream Image Repository

I also randomly checked one of the other (not mine) dumps, and the Captain Dynamo(5r).zip has a heap of bad (well, they're all in black! and dark red in HxC) sectors on it. I checked it because neither Aufit nor HxC will make a working .stx file from the .SCP. Though, the .scp I dumped works perfec...
by ijor
Sat Mar 21, 2020 7:50 pm
Forum: Coding
Topic: Sync-tricks/fullscreen discussion
Replies: 120
Views: 57597

Re: Sync-tricks/fullscreen discussion

Cyprian wrote:If I understand correctly, there is no way to invoke a reset of the video counter in the middle of the screen, in order to split the screen.
I don't see how you could do that. Again, not without somehow creating an additional VSYNC pulse, which might be doable if you don't mind and you insist.
by ijor
Sat Mar 21, 2020 12:22 pm
Forum: Coding
Topic: Sync-tricks/fullscreen discussion
Replies: 120
Views: 57597

Re: Sync-tricks/fullscreen discussion

What about Video counter? Was it reset as it is done in VBL? I thought about what you're asking some times years when working on Hatari and measuring at which exact video cycle video counters are reloaded and unfortunately it won't work : my idea was to toggle to 60 Hz around line 263 at the place ...
by ijor
Sat Mar 21, 2020 12:21 pm
Forum: Coding
Topic: Sync-tricks/fullscreen discussion
Replies: 120
Views: 57597

Re: Sync-tricks/fullscreen discussion

I did some test with the 4bit hard scroll technique. Here the results (50Hz fullscreen 4 plane side scrolling on ST with about 50% processing time left): https://github.com/frankheisig71/st_side_scrl/ It wasn't as simple as it looks like. Obviously different machines behaves different, when applyin...
by ijor
Fri Mar 20, 2020 1:30 am
Forum: Floppy Disk Preservation
Topic: Floppy Disk Stream Image Repository
Replies: 272
Views: 86211

Re: Floppy Disk Stream Image Repository

Fun School 2 for the over 8's - The Hit Squad. Disk looks like it's got some water damage, but, won't really clean off. It dumped successfully, but looks very jittery, and neither Aufit nor HxC show it as having any errors, but neither hAtari or SteemSSE will load this. Can someone check if it runs...
by ijor
Mon Mar 16, 2020 8:41 pm
Forum: Hardware
Topic: GOEX for ST in the making
Replies: 50
Views: 6067

Re: GOEX for ST in the making

I was going to reply once again, but I think we made our point enough. After all, a high quality yet affordable, Gotek compatible, including speaker and OLED, I'm definitely a buyer.
by ijor
Mon Mar 16, 2020 7:10 pm
Forum: Hardware
Topic: GOEX for ST in the making
Replies: 50
Views: 6067

Re: GOEX for ST in the making

I think Hxc will be a non-issue. If the hardware is as similar to the Gotek, HxC will probably run without any changes and Jeff will do it. I prefer to have choices on the software market. Sorry Simon, but I think you are missing the point. Yes, I think we all agree that is good to have more choice...
by ijor
Mon Mar 16, 2020 12:42 pm
Forum: MiSTer
Topic: Minimig (Amiga) core discussion
Replies: 1404
Views: 336315

Re: Minimig (Amiga) core discussion

... So, that $ffff seems, to be the correct behavior there. Now the question is that all write-only chipset registers exhibit this behavior? Is there a simple BASIC for Amiga where some values can be PEEK-ed out? I know nothing specifically about the Amiga. But almost all legacy NMOS chips use an o...
by ijor
Mon Mar 16, 2020 12:12 pm
Forum: Hardware
Topic: GOEX for ST in the making
Replies: 50
Views: 6067

Re: GOEX for ST in the making

FlashFloppy, and hence all derivatives as well, leverages Jeff's HxC work and software. ... Are you sure? From what I know HxC is closed source, commercial product. Was it open source at some point in the past. The HxC firmware is closed source, but the software is open source. Also Jeff developed ...
by ijor
Sun Mar 15, 2020 8:17 pm
Forum: Hardware
Topic: GOEX for ST in the making
Replies: 50
Views: 6067

Re: GOEX for ST in the making

Looks great. Thanks. However there is one thing that bothers me with all these FlashFloppy derivatives. Quote from the store selling the Goex: Credits: GOEX drive comes preinstalled with latest version of great FlashFloppy firmware by Keir Fraser. Please consider a donation to the developer. FlashFl...
by ijor
Thu Mar 12, 2020 5:02 pm
Forum: MiSTer
Topic: Newbie questions
Replies: 690
Views: 184207

Re: Newbie questions

Sorgelig wrote:With wise use FPGA + HPS can push the limits much further. Retro CPU emulation is better on HPS while video and other parts of chipset is better on FPGA. So i don't agree that we a close to limits, especially on hybrid systems.
Yes, hybrid emulation is a very interesting area.
by ijor
Tue Mar 10, 2020 2:28 am
Forum: MiSTer
Topic: Newbie questions
Replies: 690
Views: 184207

Re: Newbie questions

Mostly because of the operating system, you can miss a frame now and then, yet most software emulation issues are resolved by adding buffers: video sync problem? Add a double or triple frame buffer, audio cracking? Set a bigger audio buffer, etc.. From my humble opinion this where most of the overa...
by ijor
Sun Mar 08, 2020 3:32 am
Forum: Steem
Topic: Lemmings with 2 mice on windows 10 - Atari Steem Emulator?
Replies: 22
Views: 8140

Re: Lemmings with 2 mice on windows 10 - Atari Steem Emulator?

MasterOfGizmo wrote:Wow. Another lesson learned ...
Hats off to your humility. Many people here don't have half of your knowledge but would never reply like this.

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