17 Oct
2007
17 Oct
'07
2:29 a.m.
On Tue, 16 Oct 2007, Alexandre Souza wrote:
Ehmm, you've replied to a posting that has apparently never appeared on
the list, at least it didn't arrive here... Who was the original poster?
Anyway the machine's not working as it halted at $01F6, or did you
(->original poster) halt the machine with internal HALT switch? The
routine around 01F6 (specifically 01EE-01FA) is POST 'G' "Keyboard
Test".
It enables interrupt 3 and busy waits for a short time:
; --- Test G ---
; Keyboard Test
01EE 8BC7 LBI R11, #'G'
01F0 7B50 MOVB (R5)+, R11
01F2 1440 CTRL $4, #$40 ; enable int.3 and typamatic
01F4 AF00 ADD R15, #$01
01F6 CF04 SS R15
01F8 F005 BRA $01F4 ; small delay
01FA 1442 CTRL $4, #$42 ; disable typamatic
Christian
But I'd
like to see what I can do about the monitor. The picture exhibits
a strange behavior that I can't say I've seen before. The horizontal
retrace seems to "fold" over itself in the middle (like the electron gun is
doing a "loop" in the center of the screen for each line). I've taken a
(terrible) picture of the fault and put it at:
http://yahozna.dyndns.org/scratch/5120disp.jpg). The picture's also a bit
jumpy. I've tinkered a bit with the various adjustments on the CRT's PCB
but it doesn't make any appreciable difference.
Have phun on the horizontal circuit caps. There is one shorted or with a
huge loss probably on the yoke line. 