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HP-97 decimal point with ghost segment d
08-01-2020, 01:14 PM (This post was last modified: 08-01-2020 04:00 PM by AndiGer.)
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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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RE: HP-97 decimal point with ghost segment d - AndiGer - 08-01-2020 01:14 PM

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