Search found 644 matches

by Arne
Tue Mar 31, 2020 4:01 pm
Forum: Hardware
Topic: Installing the PAK68/3
Replies: 141
Views: 25398

Re: Installing the PAK68/3

TheNameOfTheGame wrote:Anyone have one of these "buffer boards΅ it mentions?
Yes
by Arne
Tue Mar 31, 2020 9:12 am
Forum: Hardware
Topic: ATARI 520 STF RAM : mix of 100ns and 120ns ?
Replies: 4
Views: 595

Re: ATARI 520 STF RAM : mix of 100ns and 120ns ?

In general it is no problem mixing DRAMs with different access times. A buddy once witnessed an upgraded Mega ST (2MB -> 4MB) not booting where each bank had a large discrepancy in access time to the other (70ns to 120/150ns IIRC). We could not figure out why. Populated both banks with 70ns and it b...
by Arne
Fri Mar 27, 2020 7:47 pm
Forum: Hardware
Topic: MegaST2 with constant resets
Replies: 46
Views: 3292

Re: MegaST2 with constant resets

I swapped the 7606 between FDC and FDD these days - bad idea. The 74F04 I used seems to have problems pulling the level to high on the DIRC pin. https://i.ibb.co/Hzq10Qs/DS1-Z-Quick-Print4.gif So I swapped it back to the 7606 re-soldered all pins around the FDC and now it can read my disks. Many tha...
by Arne
Fri Mar 27, 2020 12:40 pm
Forum: Hardware
Topic: MegaST2 with constant resets
Replies: 46
Views: 3292

Re: MegaST2 with constant resets

I checked FDD and flat-ribbon cable on another Mega. But you may remember what I wrote in the beginning about different FDDs giving different results (write-protect error...).
by Arne
Fri Mar 27, 2020 12:20 pm
Forum: Hardware
Topic: MegaST2 with constant resets
Replies: 46
Views: 3292

Re: MegaST2 with constant resets

Update: pushed on the DMA IC and rebooted. It booted to Desktop without icons. Attached FDD and now it takes an awful amount of time till desktop appears with icons for A:, B: and Trash bin. But it cannot read any disk and any disk is displayed with 0 bytes of capacity. So at this point it behaves l...
by Arne
Fri Mar 27, 2020 12:08 pm
Forum: Hardware
Topic: MegaST2 with constant resets
Replies: 46
Views: 3292

Re: MegaST2 with constant resets

I'm glad I wrote that code yesterday evening. What I did: switch off ST insert my diag cart and deactivate it (i.e. it's got a jumper routing /CS to the EPROM/Flash - if not a pull-up takes over) switch on ST till 2 bombs are displayed activate cart press reset button Reset is a Group 0 exception bu...
by Arne
Fri Mar 27, 2020 11:31 am
Forum: Hardware
Topic: MegaST2 with constant resets
Replies: 46
Views: 3292

Re: MegaST2 with constant resets

(..) A16, maybe you could (re-)check that address line. Splendid Just as I touched the 0-Ohms resistor's leg at the center of W3 (pin 2) with my measuring lead it gave way i.e. it had broken off at some point near the solder joint. Replaced it with some wire. Now I get 2 bombs - once it made it up ...
by Arne
Fri Mar 27, 2020 11:26 am
Forum: Hardware
Topic: MegaST2 with constant resets
Replies: 46
Views: 3292

Re: MegaST2 with constant resets

Just hooked up the scope to the 3 inputs/1 output of the 74LS11. https://i.ibb.co/S5LhmZS/DS1-Z-Quick-Print1.gif I triggered on all 3 inputs and the corresponding output was always asserted as it should. Think this rules out the LS11 as a source of problems. Your hint with a cracked resistor network...
by Arne
Fri Mar 27, 2020 10:36 am
Forum: Hardware
Topic: MegaST2 with constant resets
Replies: 46
Views: 3292

Re: MegaST2 with constant resets

Well, at least I now know that my dump-code doesn't dump crap :D And your assumptions are supported by the diag cart's CRC calculations. I assume that necessary connections between CPU and Glue are fine - at least those that are needed for /ROMx signals. Glue and CPU are fine, too. But as I wrote ea...
by Arne
Fri Mar 27, 2020 8:37 am
Forum: Hardware
Topic: MegaST2 with constant resets
Replies: 46
Views: 3292

Re: MegaST2 with constant resets

I wrote a little "diag cart software" that dumps the CPU Save State Area in a loop via MFP UART (as this one was known to be working with the Atari diag cart software). This is the dump: CPU Save State Area =================== 00000380 : 12345678 00000384 : 00FD0000 00000388 : FFFF0000 0000038C : 00...
by Arne
Thu Mar 26, 2020 2:04 pm
Forum: Hardware
Topic: MegaST2 with constant resets
Replies: 46
Views: 3292

Re: MegaST2 with constant resets

I think I can come up with some solution to get the CPU save state data. Just need some time.
But I also think that it's a mechanical problem. Hard to track down.
And I think that there are two problems buried in that ST. The reset loop and the source of the T6 error in the diag.
by Arne
Thu Mar 26, 2020 9:11 am
Forum: Hardware
Topic: MegaST2 with constant resets
Replies: 46
Views: 3292

Re: MegaST2 with constant resets

So, I have been working some hours on the board yesterday. Resoldered all /ROMx vias and joints and 5V signals are back. With the 1.02 setting it sometimes boots to a white screen (ST-High) and resets as already mentioned. Sometimes it doesn't even display a white screen. So I checked the input/outp...
by Arne
Wed Mar 25, 2020 9:46 am
Forum: Hardware
Topic: MegaST2 with constant resets
Replies: 46
Views: 3292

Re: MegaST2 with constant resets

Update: The TOS 2.06 card had a contact problem: CPU A6 pin did not make proper contact with the CPU socket pin. And I always thought those precision contact sockets are reliable. I programmed your SW into a FlashROM for my cartridge. It boots right after the 2.06 logo appears. But no RAM errors det...
by Arne
Tue Mar 24, 2020 9:35 am
Forum: Hardware
Topic: MegaST2 with constant resets
Replies: 46
Views: 3292

Re: MegaST2 with constant resets

czietz wrote:Ijor can explain it much better than I could: http://pasti.fxatari.com/68kdocs/68kPrefetch.html
Will check that later.
czietz wrote:If you can burn the ROMs for a cartridge (...)
Even without the need to split the BIN using just one 8bit EPROM/Flash :D

PM sent.
by Arne
Tue Mar 24, 2020 9:06 am
Forum: Hardware
Topic: MegaST2 with constant resets
Replies: 46
Views: 3292

Re: MegaST2 with constant resets

The access to $FC3184 is a prefetch,(...) So the 68000 has a 16bit prefetch "queue"? But I cannot explain the cause. Normally I would say bad RAM, but you already ruled that out with the diagnostic cartridge. Well yes. I forgot to mention in my first post that all RAM and CPU got sockets, too. So I...
by Arne
Tue Mar 24, 2020 8:37 am
Forum: Hardware
Topic: MegaST2 with constant resets
Replies: 46
Views: 3292

Re: MegaST2 with constant resets

Latest results are (addresses accessed from last meaningful (IMHO) to crash site): FC[1..0] R/W $FC3184 2 R $FFFA10 1 W $00167E 1 R $001680 1 R $001682 1 R $1FFB38 2 R $1FFB3A 2 R $1FFB3C 2 R $1FFB3E 2 R $1FFB40 2 R $1FFB42 2 R $1FFB44 2 R ... $200002 2 R FC317A 08B90005FFFFFA11 L01D1:BCLR #5,$FFFFF...
by Arne
Mon Mar 23, 2020 9:45 pm
Forum: Hardware
Topic: MegaST2 with constant resets
Replies: 46
Views: 3292

Re: MegaST2 with constant resets

Last message for today: you were right. Accesses to $200000 and before contain FC[1..0] = $2 -> User code!
by Arne
Mon Mar 23, 2020 8:55 pm
Forum: Hardware
Topic: MegaST2 with constant resets
Replies: 46
Views: 3292

Re: MegaST2 with constant resets

Makes sense. In case of all ST with < 4MB TOS RAM test will always read $FFFF (pull-ups) at some point. But why should it try to execute code ? If it helps I could swap /LDS and /UDS (as we are dealing with 16bit accesses anyway) for FC0 and FC1. Anyway: the addresses accessed prior to $200000 are w...
by Arne
Mon Mar 23, 2020 7:50 pm
Forum: Hardware
Topic: MegaST2 with constant resets
Replies: 46
Views: 3292

Re: MegaST2 with constant resets

So, regarding your request to trigger for $FC0B50 I am a step forward. The LA refused to successfully trigger for $FC0B50, so I triggered for /RESET again with a large amount of samples ahead. I saved them as a TXT (1.7GB) and searched it for $FC0B50. And found it :-) The sequence I see with address...
by Arne
Mon Mar 23, 2020 6:12 pm
Forum: Hardware
Topic: MegaST2 with constant resets
Replies: 46
Views: 3292

Re: MegaST2 with constant resets

Yes, you are probably right. But I don't dare to touch the system now. LA is back in business and I got the reset loop with 1.02 again. Unfortunately the LA SW does not trigger on $FC0B50. But as I said before: it's Chinese stuff. The SW does have its quirks.
by Arne
Mon Mar 23, 2020 11:32 am
Forum: Hardware
Topic: MegaST2 with constant resets
Replies: 46
Views: 3292

Re: MegaST2 with constant resets

As I still cannot find any problem with that LA-PCB I removed it and used the plain TOS 1.02 setting to monitor D4 (as an example). Constantly pressing the [Single] button on my scope I was able to see a pattern - at least I think so - on about 10+ loops. Just after reset (at the beginning of the lo...
by Arne
Mon Mar 23, 2020 10:40 am
Forum: Hardware
Topic: MegaST2 with constant resets
Replies: 46
Views: 3292

Re: MegaST2 with constant resets

Using the Examine memory command

Code: Select all

R 380
yields

Code: Select all

00
as result. :( Sh*t
by Arne
Mon Mar 23, 2020 10:23 am
Forum: Hardware
Topic: MegaST2 with constant resets
Replies: 46
Views: 3292

Re: MegaST2 with constant resets

I would need to see that happens before the exception handler is invoked. And that is currently a problem. As I wrote earlier yesterday it won't boot i.e. as I found out later: it won't boot with my LA-PCB (to attach the grabber cables) anymore. D0-D13 + D15 all rise just to 2V. D14 looks fine. Sam...
by Arne
Sun Mar 22, 2020 9:18 pm
Forum: Hardware
Topic: MegaST2 with constant resets
Replies: 46
Views: 3292

Re: MegaST2 with constant resets

I've checked Atari ST Internals and the TOS documentation looks totally different. At FCOBA2 we have: move.w #7,-(a7) ; R/O, hidden and system files I didn't look at the ST Internals, but I assume this is a disassembly of TOS 1.00. Of course that would be totally different from TOS 1.02. Yes of cou...
by Arne
Sun Mar 22, 2020 2:55 pm
Forum: Hardware
Topic: MegaST2 with constant resets
Replies: 46
Views: 3292

Re: MegaST2 with constant resets

Trigger condition could (!) work but it's Chinese stuff. So you never know. Checksums for 1.02 and 1.04 on that particular machine. ROM checksum test TOS in ROM: although six ROMs are shown, there may actually be only two. Version 1.2 German PAL checksum crc H2 805B FC39 cs error H1 FB03 FC39 cs err...

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