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Incredibly clear!!!! Well done, complete and wonderful. It could not better than this!!!!
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Thank You for fast delivery for the sheme.
Everything allright.
Thanks & best regards Franz
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again you did a very good job. It was fast too. Photocopy are really readable and clear
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Probably it never existed a 1081 official service manual from Commodore, it's look more like a NAPCEC service manual & diagrams compilation of the 1084 series and his variants, like the nap6523, 8cm505, 1084S, 1084P and obviously the 1081. It's more complete than other scans and the quality of the scans also are far superior. It has two circuit diagrams variants of the 1081, mono and stereo versions. It doesn't include a diagram for the Philips CM8500 or CM8501, they look like the 1081 but they are slightly different.
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Rapid, clear well done as all the scheme I downloaded from this site. Great job very functional and very useful
CPU (LSI1: MSM6521-13)
Containing a sound data ROM and a DAC (Digital to Analog Converter), the CPU provides sound waveform in accordance with the pressed key and selected tone. The CPU also drives LEDs in the illuminated keyboard directly. The following table shows the pin functions of LSI1.
Pin No. 1~7 8 9 10 ~ 13 14 ~ 17 18 19 20, 21 22 23 24 ~ 26 27 28 29 30 31 ~ 38 39 ~ 46 47 ~ 58 59 60
Terminal LY1 ~ LY7 LVDD1 LGND2 LX0 ~ LX3 LX4 ~ LX7 LVDD2 GND2 COSI, COSO VDD GND1 TEST1 ~ TEST3 RESET AVDD OUT AGND KI0 ~ KI7 KO0 ~ KO7 � LGND1 LY0
In/Out Out In In Out Out In In In/Out In In In In In Out In In Out � In In
Function Keyboard LED drive signal output +5 V source for the built-in LED driver Ground (0 V) source for the built-in LED driver Keyboard LED drive signal output Not used. +5 V source for the built-in LED driver Ground (0 V) source 21.725 MHz clock pulse input/output +5 V source Ground (0 V) source Not used. Connected to ground. Reset signal input. Power OFF: 0 V, Power ON: +5 V +5 V source for the built-in DAC Sound waveform output Ground (0 V) source for the built-in DAC Input terminal for keys and switches Key and switch scan signal input Not used. Ground (0 V) source for the built-in LED driver Keyboard LED drive signal output
C12
Filter Block
Since the sound signal from the CPU is a stepped waveform, the filter block is added to smooth the waveform.
AVDD
T2 2SC1740SQ R12 C9
R11 C10
R13
R14
C11
AG
AG
AG
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