Search found 3037 matches

by ijor
Sat Nov 30, 2019 11:47 am
Forum: 680x0
Topic: The secrets of the 68000
Replies: 22
Views: 3624

Re: The secrets of the 68000

I edited the post with the article about the I/N field. One section was expanded because I was told it was difficult to understand. The attached PDF article was also updated accordingly. There are currently also some other differences in exception handling when comparing real HW with emulation, for ...
by ijor
Thu Nov 28, 2019 7:14 pm
Forum: Hardware
Topic: Greaseweazle disk image reader writer
Replies: 17
Views: 3471

Re: Greaseweazle disk image reader writer

Btw, it is just by chance that the name is so similar to the Catweasel, a predecessor of all these "flux level" devices?
by ijor
Thu Nov 28, 2019 7:09 pm
Forum: Hardware
Topic: Greaseweazle disk image reader writer
Replies: 17
Views: 3471

Re: Greaseweazle disk image reader writer

It is very nice to have an open source alternative to SCP and the Kryoflux. But unless somebody will provide this fully assembled, and with software that would run directly without something like phyton, then it would be very restricted. Btw, I'm not sure this device is suitable for older 5.25 drive...
by ijor
Wed Nov 27, 2019 1:02 am
Forum: 680x0
Topic: The secrets of the 68000
Replies: 22
Views: 3624

Re: The secrets of the 68000

I guess no emulator handles this correctly? Not that I know. But I'm in contact with Toni Wilen (Winuae maintainer) and already let him know. Well, what is "correctly"? If i understand that, it could also happen that an interrupt happens as the "next" instruction, which would ha...
by ijor
Tue Nov 26, 2019 1:18 pm
Forum: 680x0
Topic: The secrets of the 68000
Replies: 22
Views: 3624

Re: The I/N field on the bus and address error stack frame

Attached in a small article I wrote about the bus and address exception stack frame. Whole article in PDF form (updated version): M68000-ExceptionStackFrame.pdf I am pasting here the sections relevant to the I/N field. But it might be easier to understand the context checking the whole article. ...,...
by ijor
Tue Nov 26, 2019 1:09 pm
Forum: MiST
Topic: Mister SNES port to MIST possible?
Replies: 279
Views: 42106

Re: Mister SNES port to MIST possible?

AFAIK the skew created by the zero delay mode affects all off the clock networks. Aligning and compensating are two different things. All internal clocks are aligned, unless explicitly shifted, and don't require compensation. But the external output is not aligned with the internal ones and might h...
by ijor
Tue Nov 26, 2019 1:00 pm
Forum: 680x0
Topic: The secrets of the 68000
Replies: 22
Views: 3624

Re: The secrets of the 68000

Another clue might be that for "MOVE.W D0,-(A0)" the write access that causes the address error only happens after the prefetch for the next instruction. Unlike you, I don't know how the internal sequencer of the 68000 works, but one could assume that the I/N bit due to the upcoming TRACE...
by ijor
Tue Nov 26, 2019 2:07 am
Forum: News & Announcements
Topic: FX68K Cycle accurate 68000 core
Replies: 56
Views: 21808

Re: FX68K Cycle accurate 68000 core

Last update adds support for HALT single step. Not relevant for most platforms. On most platforms HALT is used only for hardware reset. Please note that a new input port, HALTn, has been added! Initially I tried using SV default input port values to avoid modifications when this feature is not used....
by ijor
Tue Nov 26, 2019 1:27 am
Forum: MiST
Topic: Mister SNES port to MIST possible?
Replies: 279
Views: 42106

Re: Mister SNES port to MIST possible?

For example, I changed the clk_sdram pin in SiDi for another. Now the SNES core doesn't work for me at any phase. The only way to make it work has been in phase 0 and with the option in PLL Zero delay mode. Now it is very stable. I'm not sure using Zero delay is a good idea in this case. Zero Delay...
by ijor
Mon Nov 25, 2019 7:43 pm
Forum: 680x0
Topic: The secrets of the 68000
Replies: 22
Views: 3624

Re: The secrets of the 68000

EDIT: So -- still not tested on the actual HW -- I'd now say that the state of the bit depends on whether your code is inside another exception handler. An address error while processing a group 0 exception (bus or address error) will cause a double fault and halt the CPU, but the behav...
by ijor
Mon Nov 25, 2019 5:44 pm
Forum: MiSTer
Topic: FX CAST Atari ST core
Replies: 332
Views: 132459

Re: FX CAST Atari ST core

I don't know if is it relevant or not, but in the MiST's ikbd controller, the original CPU used was buggy in its interrupt processing - it used edge triggered interrupt where it should use level triggered ones. And when it missed an edge, the keyboard/mouse/joystick stopped. No. HD6301 interrupts a...
by ijor
Mon Nov 25, 2019 5:39 pm
Forum: 680x0
Topic: The secrets of the 68000
Replies: 22
Views: 3624

Re: The secrets of the 68000

I didn't test my theory, because that would be cheating. ;-) Not at all. You can test :) But it is revealing that you omitted the operand size from the MOVE instruction. Thus, my guess is as follows: It depends on that size. If there is only one write access (.B / .W), the instruction is considered...
by ijor
Mon Nov 25, 2019 5:32 pm
Forum: Floppy Disk Preservation
Topic: Floppy Disk Stream Image Repository
Replies: 122
Views: 48558

Re: Floppy Disk Stream Image Repository

Good job and thanks DrCoolZic. And I hope Kodak80 will reconsider his decision. While I can understand his frustration, I don't share the reaction.
by ijor
Mon Nov 25, 2019 4:19 pm
Forum: News & Announcements
Topic: FX68K Cycle accurate 68000 core
Replies: 56
Views: 21808

Re: FX68K Cycle accurate 68000 core

You can check this WinUAE thread for a list of all the changes that were detected using the cputester against real HW : http://eab.abime.net/showthread.php?t=98746 . So far, all those changes were merged into Hatari's devel version? As I just commented by PM, both to Nicolas and to Toni, I believe ...
by ijor
Mon Nov 25, 2019 4:15 pm
Forum: 680x0
Topic: The secrets of the 68000
Replies: 22
Views: 3624

The I/N field on the bus and address error stack frame

Quiz of the day for advanced 68000 coders: It has been observed that the instruction MOVE Dn,-(An) , if it provokes a bus or address error when writing the operand, the I/N bit would be set on the exception stack frame. According to the official documentation, the I/N set indicates that the processo...
by ijor
Mon Nov 25, 2019 4:14 pm
Forum: 680x0
Topic: The secrets of the 68000
Replies: 22
Views: 3624

The secrets of the 68000

I plan to use this thread to post and discuss about interesting undocumented aspects of the 68000.
by ijor
Mon Nov 25, 2019 3:59 am
Forum: MiST
Topic: Mister SNES port to MIST possible?
Replies: 279
Views: 42106

Re: Mister SNES port to MIST possible?

Yes, i´m use the AS4C16M16SA-6TCN sdram memory. In snes core is estable at -(1000-1500ps) sdram clk phase. Others cores not have this issue. ... with micron memories there is no problem but unfortunately they are no longer manufactured. The problem here is probably actually that the Alliance chip i...
by ijor
Mon Nov 25, 2019 3:49 am
Forum: MiSTer
Topic: FX CAST Atari ST core
Replies: 332
Views: 132459

Re: FX CAST Atari ST core

Works with my 64MB setup, but then again it also passes at 167MHz. Ijor, what is the max speed used by your SDRAM controller setup with FX CAST? Currently the core's SDRAM controller uses a very conservative 64 MHz frequency. Do you plan to support hard disks and/or .STX floppy images in an upcomin...
by ijor
Sun Nov 24, 2019 11:14 am
Forum: Hardware
Topic: Atari ST HDMI solution from The backofficeshow
Replies: 10
Views: 2358

Re: Atari ST HDMI solution from The backofficeshow

I checked my ST with nine different displays using this device. This was a combination of three monitors and six televisions. The color resolutions worked with none of them. Not a single one. The high resolution mode worked on some of them, and never well. It had a splotchy, grainy image at best. N...
by ijor
Sat Nov 23, 2019 8:58 pm
Forum: MiST
Topic: Mister SNES port to MIST possible?
Replies: 279
Views: 42106

Re: Mister SNES port to MIST possible?

It's worse, but still lot of room to play: 3.562 SDRAM_DQ[4] sdram:sdram|sd_din[4] pll|altpll_component|auto_generated|pll1|clk[0] pll|altpll_component|auto_generated|pll1|clk[1] 1.108 -0.232 1.113 Yes, but: 1 - This is with the smaller 1.1 shift that works better for them. 2 - This is not the fast...
by ijor
Sat Nov 23, 2019 7:39 pm
Forum: MiSTer
Topic: FX CAST Atari ST core
Replies: 332
Views: 132459

Re: FX CAST Atari ST core

dgarman wrote:But not with 64MB.


It works for others with a 64MB DRAM board. Please double check and remember to load an ST image file.
by ijor
Sat Nov 23, 2019 7:39 pm
Forum: MiSTer
Topic: FX CAST Atari ST core
Replies: 332
Views: 132459

Re: FX CAST Atari ST core

... I remember reading that inputs may be problematic with an unpowered hub, which i have (i tested with a keyboard, a mouse and a ps3 controller). And i can say that there are indeed problems, but they are very random: I still had no time to look into that issue. I suspect a combination of problem...
by ijor
Sat Nov 23, 2019 7:25 pm
Forum: MiST
Topic: Mister SNES port to MIST possible?
Replies: 279
Views: 42106

Re: Mister SNES port to MIST possible?

ManuhFeri wrote it uses -6 speed grade Alliance module, which has: tOH = 2.5, tAC(3) = 5 vs the one in the Micron datasheet for -75: tOH = 2.7 and tAC(3)= 5.4. Input setup/hold times are the same: 1.5/0.8 Yes, but I suspect the datasheets might be not 100% accurate about tOH for the faster speed gr...
by ijor
Sat Nov 23, 2019 4:32 pm
Forum: MiST
Topic: Mister SNES port to MIST possible?
Replies: 279
Views: 42106

Re: Mister SNES port to MIST possible?

I've uploaded the latest tweaks to the github repo, if you can compile it from there, you can experiment with phase shifts again. On my MiST it even accepts -1100 now (and passes the timing analysis + works, too). Or if you can spot some difference between the Hynix and Alliance datasheet, I'll loo...
by ijor
Sat Nov 23, 2019 4:31 pm
Forum: MiST
Topic: Mister SNES port to MIST possible?
Replies: 279
Views: 42106

Re: Mister SNES port to MIST possible?

To say what is the best value that works for me, without a doubt the 5 value works better but no well. Tested in a Mistica via rgb and my sdram memory is Alliance , maybe that will help. Only test 14 compiled with c0 at 1100 works estable in my mistica Can you please post a high rez picture of your...

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