[its-hackers] Time standing still

Lars Brinkhoff lars at nocrew.org
Tue Apr 6 13:29:19 CEST 2021

Paul Svensson wrote:
> The clock on SV has stopped running.
> I can set it with PDSET, but it stays stuck to whatever I set it to.
> Where should I look for the problem ?

I believe you are running KLH10 so it's a KS10.  Checking ITS sources I
see date and time should come from GPDTIM in SYSTEM; TIME >, and it uses
the KS10 RDTIM instruction.  You could try putting a breakpoint there.
Maybe this code has crossed a limit or overflow condition?  What is that
"interesting number"?

        RDTIM A         ; Read clock into A!B
        TLC A,1729.     ; "A most interesting number"
        TLNE A,-1       ; Does the clock look like it has been set?
         JRST GPDTM2    ; Must have been reset
        DIVI A,KSFREQ   ; Convert to 60ths
        SUB A,PDTIME    ; Subtract offset

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