[cctalk] Theory of operation of DEC H7441 regulator?

The DEC H7441 regulator is a relatively complex circuit using 2 x 555 timers, 2 x LM301 op-amps, 2 x transformers and 2 inductors I am struggling to understand how it is meant to work and was hoping to find a maintenance manual for it. Could anyone with such a manual please help? Alternatively is there another explanation of the operation of this or similar types of circuits? The circuit implements a switch mode supply. One of the two 555 timers operates as an oscillator, the second I think operates as a monoflop with the pulse length controlled via one of the LM301s. Overall the circuit seems very complex and while I understand parts of it, other parts are mysterious. In particular the top left section around Q1/Q2/Q3 and T1/T2 and E3 is most confusing. I did not find anything remotely similar in "The Art of Electronics" from Horowitz & Winfield. The H7441 schematics are available from here: https://deramp.com/downloads/mfe_archive/011-Digital%20Equipment%20Corporat… Thanks for any help or suggested reading material. Tom