M7264 Troubleshooting

On 06/08/2019 10:37 PM, Noel Chiappa via cctech wrote: Yes that is what the para quoted above implies. The resence of Eprom and serial are unique to the F11 based and later J11 quad width cards. All of the Qbus processor cards could boot to Eprom (TEV11) just like the Unibus 11s. And yes the KDF11 cpu does rely on higher level code inside the microcode its how that code was structured [and made to fit]. Also there are three cards for the KDF11, one dual width, and two quad width. The 11/23 early did not boot all devices and had different eproms (board level difference) than the later 11/23+ hence the + [and different part designations in the Mseries] designation. Back then FS noted that when requesting replacement boards and history requires it. Save for the CPU and microcode are entirely different. ODT as a function is defined to do certain things how its done is vaguely similar at best. While implemented in ucode how its done and depnendancies are very unique to the each (again cp1600 and F11) Yes and unlike many here I have CPUs of all three form factors operational. However ODT on the dual width CPU does require a serial card as there is no way to talk to it without. That is an important difference especially if jumpered for ODT. Actually my "11" series Qbus collection includes all of the CPUs from the LSI11 though J11 based. And the bus versions are greater from the LSI11 early (and H11) though the later ones with PMI some specific to devices like the RL11 controller board set. However LSI-11/23 whatever that is, typo? So I will say the CP1600 processor of LSI-11 and the F11 (KDF-11)processor have major differences in how ODT works internally and on the bus and the code that does that are very different. To the user with a terminal its not very visible but to the service person (or someone assembling a system) it makes a difference. ODT had a specification and if you reffered to it that inside DEC it was not clear if it was microcode only that what the user/field service saw behaved in a very specific way. When applied to a specific processor it had deeper meaning. Some of that was factory test related. That Specification was an evolved thing as LSI-11 (cp1600) lead to additions and minor changes that were important to Field service and manufacturing. Glad to see someone reads the books. There are other differences on power up and run states. Like the ram and console dependencies But all the M7264 posts were boiled down to the problem of not reading and understanding that ODT for that version of the CPU had dependencies. As well as the evolution of Qbus family of PDP11 CPUs and their low level and bus level idiosyncrasies. Most never refer to the LSI-11/23 that way to mean KDF-11 CPU its was a documentation error that propagated in educational services and lead to errors. LSI-11 (CP1600) was the first generation Qbus and later was F11 or J11 (or the T11). The difference was not always small as there were subtle instruction set differences and diagnostic impacts. That always had me during my yeas at DEC going which one are you talking about, as every thing had at least three names (never minding numbers) and one was usually ambiguous or a nonspecific family name. It's not a question only the implications of how they did it. That they did it using using ucode is too road a generalization and misses implementation details. Its those details that get you when assembling systems and forgetting to include functions that are required if not used. That goes back to how DEC supported their systems when computers no longer had front panels. It was a field service requirement so they were not trying to wake a brick with nothing. Allison