Here’s how we get X displayed when we’re in FIXed display mode.
The process summarizes to:
if A & B aren’t already valid from last time (f3)
– if (w/prgm) do something else (s3)
– if (SCI mode) do something else too (M[1])
– 04164 Display X in FIX mode
– create mask in B (29999999999999)
– move it right by exponent digits (eg 0002999999999)
– round X in A to precision (M[2])
– add holes in mask to rhs of “.” to precision
– blank out the exponent ’cause this is FIXed mode
– turn the display on
end if
if f3 is 0 and A & B are already valid, the display must still be on because it jumps to after that point.
The microcode looks like:
00531 0 -> s3 00532 1 -> f2 00533 1 -> p ; P= 1 00534 c <-> m ; C= 00000000000221 M =05432100000004 00535 0 -> s11 00536 0 -> f3 ; S= ...........b ; 00537 if s3 = 0 ; if in RUN mode 00540 goto 00552 ; else see "display program step" instead 00552 if s11 = 0 ; if f3 was clear before now 00553 goto 00764 ; we can skip the following (A & B already valid) ; setup A & B for display 00554 if c[p] = 0 00555 goto 00616 ; display X in SCI notation 00556 c - 1 -> c[p] ; C= 00000000000211 00557 if c[p] = 0 00560 goto 00616 ; display X in SCI notation 00561 load 2 ; C= 00000000000221 P= 0 00562 delayed select group 1 00563 rom 0 ; display X in FIX notation 04164 jsb 04101 ; create mask in B with "2" where "." should be .04101 dispoff .04102 c -> a[x] ; A= 98000000000221 (precision,mode,ang) .04103 c <-> m ; C= 05432100000004 M =00000000000221 .04104 shiftr a[x] ; A= 98000000000022 .04105 shiftr a[x] ; A= 98000000000002 (precision) .04106 0 -> p .04107 if c[m] >= 1 ; if mantissa=0 04111 would set exp=0 too .04110 goto 04112 .04112 b <-> c[w] ; B= 05432100000004 C= 00000000000000 .04113 0 -> c[w] .04114 c - 1 -> c[w] ; C= 99999999999999 (mask) .04115 c + 1 -> c[s] ; C= 09999999999999 .04116 c + 1 -> c[s] ; C= 19999999999999 .04117 c + 1 -> c[s] ; C= 29999999999999 (2 mask) .04120 b <-> c[w] ; B= 29999999999999 C= 05432100000004 .04121 0 -> f2 .04122 return 04165 a + c -> a[x] ; A= 98000000000006 =precision+exponent 04166 jsb 04266 .04266 a + 1 -> a[x] ; A= 98000000000007 =precision+exponent+1 = digits .04267 12 -> p ; P= 12 .04270 goto 04124 .04124 a - 1 -> a[x] ; A= 98000000000006 .04125 goto 04206 .04206 if p # 2 .04207 goto 04123 .04123 p - 1 -> p ; P= 11 .04124 a - 1 -> a[x] ; A= 98000000000005 .04125 goto 04206 ; P= 10 A= 98000000000004 ; P= 9 A= 98000000000003 ; P= 8 A= 98000000000002 ; P= 7 A= 98000000000001 ; P= 6 A= 98000000000000 ; P= 5 A= 98000000000999 .04125 goto 04206 ; P = digits blanked on the right .04126 0 -> a[w] ; A= 00000000000000 ; copy the blanked frac to A, & the exponent .04127 c -> a[wp] ; A= 00000000000004 ; round the value (2*undisplayed frac adds 1 if >=0.5) .04130 a + c -> a[m] ; A= 05432100000004 .04131 goto 04135 .04135 a -> b[x] ; B= 29999999999004 .04136 return 04167 if a[xs] >= 1 ; if exp sign negative 04170 goto 04364 ; about to shift decimal point to the right by exp places 04171 13 -> p ; P= 13 04172 p - 1 -> p ; P= 12 04173 shiftr b[ms] ; B= 02999999999004 04174 a - 1 -> a[x] ; A= 05432100000003 04175 goto 04361 04361 if p # 3 ; but if going into exponent area 04362 goto 04172 ; do s/thing else ; P= 11 B= 00299999999004 A= 05432100000002 ; P= 10 B= 00029999999004 A= 05432100000001 ; P= 9 B= 00002999999004 A= 05432100000000 ; P= 8 B= 00000299999004 A= 05432100000999 04175 goto 04361 04176 jsb 04272 ; get prec,mode,ang to a[x] .04272 c <-> m ; C= 00000000000221 M =05432100000004 .04273 c -> a[x] ; A= 05432100000221 .04274 c <-> m ; C= 05432100000004 M =00000000000221 .04275 return 04177 goto 04151 04151 if a[xs] >= 1 ; if DSP . 1 or more 04152 goto 04231 ; about to open mask holes for digits on rhs of decimal ; a[xs]= precision ; p points to the "." in B ; so code below is "for (; a[xs]>0; a[xs]--) b[p--]=0" 04231 p - 1 -> p ; P= 7 04232 if p # 2 ; but still check not in exp area 04233 goto 04147 04147 0 -> b[p] ; B= 00000209999004 04150 a - 1 -> a[xs] ; A= 05432100000121 04151 if a[xs] >= 1 04152 goto 04231 04231 p - 1 -> p ; P= 6 04232 if p # 2 04233 goto 04147 04147 0 -> b[p] ; B= 00000200999004 04150 a - 1 -> a[xs] ; A= 05432100000021 04151 if a[xs] >= 1 04152 goto 04231 ; always blank out the exponent in FIX mode 04153 0 -> a[x] ; A= 05432100000000 04154 a - 1 -> a[x] ; A= 05432100000999 04155 a -> b[x] ; B= 00000200999999 04156 goto 04321 ; put sign of X in a[13] 04321 c -> a[s] ; 04322 if s5 = 0 04323 goto 04331 ; wrap up 04331 clearstatus ; S= ............ 04332 goto 04326 04326 delayed select group 0 04327 rom 1 00730 0 -> s9 00731 1 -> s10 ; S= ..........a. ; display 00732 disptoggle ; =" 5432.10" 00733 goto 00622 waitloop2: 00622 ... waitloop3: 00764 ... waitloop4: 00774 ... 00777 goto 00726
Anything that gets to 00531 is up to the display routine and about to go back into the wait loop.
See also:
HP-65 Display program step
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