HP-97 decimal point with ghost segment d
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08-01-2020, 01:14 PM
(This post was last modified: 08-01-2020 04:00 PM by AndiGer.)
Post: #8
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RE: HP-97 decimal point with ghost segment d
Today I took the time to measure with the oscilloscope what Tony suggested.
Isolated SD and SH, i.e. pins 6 and 7 of ROM0 or pins 12 and 16 out of 18 of the golden forks (XA2P1 in the service manual where I found pin assignment shown in figure 4-10 isn't that it is in reality). Calculator switched on doesn't show neither DP nor segment d of the initial 0.00 display. With 6 or 7 times 1 in the display I got the attached picture. So it seems that ROM0 generates not only segment h but also segment d for the decimal point. So - I don't care that much. This way I got a very special calculator (board), maybe unique ;-). Next to try is the card reader. |
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Messages In This Thread |
HP-97 decimal point with ghost segment d - AndiGer - 07-20-2020, 03:29 PM
RE: HP-97 decimal point with ghost digit d - Paul Berger (Canada) - 07-20-2020, 06:06 PM
RE: HP-97 decimal point with ghost digit d - AndiGer - 07-21-2020, 03:43 PM
RE: HP-97 decimal point with ghost digit d - teenix - 07-22-2020, 12:19 AM
RE: HP-97 decimal point with ghost digit d - Roland57 - 07-22-2020, 10:36 AM
RE: HP-97 decimal point with ghost digit d - AndiGer - 07-22-2020, 04:17 PM
RE: HP-97 decimal point with ghost digit d - teenix - 07-23-2020, 01:06 AM
RE: HP-97 decimal point with ghost segment d - AndiGer - 08-01-2020 01:14 PM
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