> -----Original Message----- > From: cctalk <[email protected]> On Behalf Of Bjoren Davis via > cctalk > Sent: 03 May 2021 20:45 > To: [email protected] > Subject: Re: Documentation for F11 Chipset? > > Hello Paul and Rob, > > The next thing I did was to hook up a logic analyzer to the address lines on > the ROM. This told me how far I got with the boot sequence before it > restarted. > > I disassembled the ROM and have some portions of it semi-decoded so that > may be helpful. If you like I can send you the text file I have. > > Another helpful thing for me was to take the Xhomer emulator > https://xhomer.isani.org/xhomer/ and instrument it to give me a "good" > ROM boot sequence (correlated nicely with device accesses) and compare > that with what I saw with my logic analyzer. > > That's how I figured out my ROM was failing to see an interrupt from the EPCI > (I think the ROM was running the EPCI in loopback mode) and so it was > resetting. > > I have to say: the POST on the PC3XX is impressively thorough, but the > mechanism for reporting failures is absolutely atrocious (4 LEDs and, if > you're > lucky, a cryptic octal error code on the screen). >
In my case all the LEDs come on and stay on, so it isn't executing any instructions at all. I will look at the ROM next. > I do have a functional 350 that I can instrument, so let me know if I can > help. If you get the opportunity I would be interested to know how the following signals look: E22 pin 3 CT1 PT 4 (E22 pin 1) CT1 PHASE L (E46 pin 8) You can see how it looks for me here: https://rjarratt.files.wordpress.com/2021/05/bus-timeout-trace.png Yellow: E22 pin 3 Cyan: CT1 PT 4 (E22 pin 1) Pink: CT1 PHASE L (E46 pin 8) Not shown is trigger off E70 pin 15. > > --Bjoren > > On 5/3/2021 2:29 PM, Paul Koning via cctalk wrote: > > > >> On May 3, 2021, at 2:23 PM, Rob Jarratt via cctalk <[email protected]> > wrote: > >> > >> Sadly my machine is not at the point where I can attach a console of any > kind. The CPU is being reset every 13us by a bus error. I am having trouble > working out why though. I have got as far as working out that is the CT2 TIME > OUT signal, but just why that is active isn't entirely clear to me. It would > help > to have a working machine to compare it to! > >> > >> Regards > >> > >> Rob > > That sounds like it's trying to access the boot ROM and not getting an > answer. > > > > paul > > > >
