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Tim's Amstrad NC Users' Site

A Surgical Guide to the Amstrad Notepad Computer

By Hans Boehling
An extract from the full article on Hans Boehling's website

Screen Shot of the main screen of the German NC100

How to open the NC100

Before dis-assembling the Notepad you should save all your data! Then put your Notepad on the table face down. Remove the four AA batteries (if fitted), then unscrew the five screws (one under the battery cover).
In Figure 1 below they are marked with a '*' sign.

One screw fixes the cover of the firmware EPROM. Place the Notepad the right way up and lift off the upper part of the case. Be careful, because the display is still connected to the main-board via a folio-flat-cable and so is the speaker! Don't be nervous, the cables can be simply pulled out of their sockets. Now you can separate the covers.

Figure 1

What's inside?

Inside the NC100 is a SMD layout. I have a German NC100 and the plate is labelled Amstrad plc 4500-001P-1, NA999-32142, manual marked C (A-H) and 1 (1-8) . All IC's are SMD apart from IC303 which is on the backside of the NC100 (behind the firmware EPROM cover). On the drawing below I have labelled all IC's :

Figure 2

The table below gives a description of the IC's in the NC100 :

IC-# Label Pins Description
Z84C00 CMOS 6MHz Z80 compatible microprocessor
302 NEC Japan
PLCC 136
µPD 65034
303 NEC Japan
DIL 32
27C001 CMOS EPROM 256K*8 bit
Firmware EPROM
304 NEC Japan
SO 28
µPD 43257 A = CMOS SRAM 32K*8 bit
Memory layouted as an SO 32 (32 pin)!
305 NEC Japan
SO 28
µPD 43257 A = CMOS SRAM 32K*8 bit
307 T 9224 HB
8521 AM
TC8521 Real-Time-Clock
308 NEC Japan
D71051 GU
SO 28
µPD 71051 UART (parallel to serial converter)
309 NEC Japan
D4711 AG
SO 20
µPD 4711 RS232-driver (shift level to /- 10V)
310 Not placed 2*7=14
SO 14
Labeled on the layout as HC08 (74HC08?)
311 D4584G 2*7=14
SO 14
4584 CMOS-Logic 6xSchmitt-Trigger
312 C339 G 2*7=14
SO 14
??? (Could be LM339 which is 4xComparator)
313 D4013G 2*7=14
SO 14
4013 CMOS-Logic 2xD-Flip Flop with set and reset
314 D4584G 2*7=14
SO 14
4584 CMOS-Logic 6xSchmitt-Trigger

The final questions

  • I have read out the firmware EPROM of my German NC100. I have version 1.06.
  • Is this the last version? Who can send me the English firmware? (BIN or HEX file)
  • Who knows something about IC302 (µPD 65034)?

Thanks... Hans Boehling

You can send email to Hans Boehling at and visit his website at where you can find the full version of this article, plus more information on each of the IC's mentioned in the table above (including pin-outs).

© 1997 – 2024 Tim Surtell

Tim's Amstrad NC Users' Site

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