YORKE annunciator - HP-48/49

[Peter HOFMANN]

I wanted to ask, if anyone knows the number of the output pins of the YORKE corresponding to the annunciators (right shift, left shift, alphabetics ...) for indication on the lcd-display OR the pin numbers on the lcd-display for the 6 annunciatorrs ?

May be there is a common line + 6 lines connecting the YORKE with the lcd display ?

For the annunciators indication on the lcd are the corresponding bits on the adresses 0010B/0010CH to be set/reset, especially Bit 3 in address 0010CH for the basically switching ON for the annunciators.

The effect could be, that the key sequences for the annunciators are working okay, but WITHOUT indication on the lcd display ! YORKE output port defect ?

Information appreciated
Peter

[TomC]

I believe the annunciators are independent of the multiplexed LCD drivers, but we need a better schematic of the HP48.

TomC

(08-15-2016 09:29 AM)Peter HOFMANN Wrote:  I wanted to ask, if anyone knows the number of the output pins of the YORKE corresponding to the annunciators (right shift, left shift, alphabetics ...) for indication on the lcd-display OR the pin numbers on the lcd-display for the 6 annunciatorrs ?

May be there is a common line + 6 lines connecting the YORKE with the lcd display ?

For the annunciators indication on the lcd are the corresponding bits on the adresses 0010B/0010CH to be set/reset, especially Bit 3 in address 0010CH for the basically switching ON for the annunciators.

The effect could be, that the key sequences for the annunciators are working okay, but WITHOUT indication on the lcd display ! YORKE output port defect ?

Information appreciated
Peter

[Peter HOFMANN]

Yes, thats correct ! May be that there is anyone with a better schematic or with the knowledge of the according pins of the YORKE ?
I am sure that it is a write-only register, a special one, because a lcd display has to be multiplexed and not only switched on/off ! The annunciators are connected directly to the YORKE and NOT to the two lcd drivers. As i mentioned, it may be possible that there is ONE common line and the "6" annunciators are set/rest via the output register(s) of the YORKE.
May be that anyone here as more information ? Thanks in advance
Peter

[cyrille de brébisson]

Hello,

I have not looked at the schematics for a while, but if my memory serves me well, there is an always connected common line (grounded), and 1 line out of the Yorke for each indicator.

You are correct in assuming that the indicators do NOT go through the LCD multiplexer chips.

Cyrille

[Peter HOFMANN]

Hi Cyrille,
Thanks for info abt common line = ground. As you mentioned each of the annunciators symbols is connected to one pin of the YORKE/lcd display ... for determination if port of YORKE or display is fault, is the knowledge of the appropriate pins of the YORKE/lcd display helpful - with a scope it can be checked - its for sure easier than toggling the bits (0010B/0010Ch) with an assemblerprogram - anyway, lets hope that there is anyone in the community, who knows that ?
Peter