Technical description

This section offers a brief technical description of the PC1403 and the enhanced model PC1403H. Remember, all the technical facts are not officially approved by Sharp, nevertheless they are collected to the best of my knowledge – most of them are extracted from the PC1403(H) user’s manual. There is also a good resource available on the web, worth to take a look at.


Sharp introduced two models of the 1403 series: the PC1403 and the PC1403H. The only difference is the RAM space, so I will mention only the PC1403 up from now:

  • Keyboard
    77 keys, separated into 4 blocks: Typewriting keys, special keys, numerical keys with basic algebra keys, scientific keys
  • Display
    24 chars, monochrome LCD Matrix, 5×7 pixel per char, contrast configurable via wheel
  • CPU
    Sharp SC 61860, 16 bit addressing range
  • Memory
    • 1403: 8KB, about 6.8KB free RAM
    • 1403H: 32KB, about 30KB free RAM (strongly recommended)

    Both use the same RAM for calculator operations (matrix, statistical, memory, etc.) and BASIC code.

  • I/O Interface
    Serial I/O interface (max. 300baud), for connection to CE-126P (thermo printer) and throughput to CE-152 (datasette)
  • Sound
    Simple multi frequency beeper
  • OS
    Basic interpreter, stored in ROM, three main running modes (calc, prog, run)
  • Power supply
    Two Lithium batteries type CR-2032, if present via CE-126P

How to open a PC1403

Some people already asked me, how to open the PC1403 safely, so here is a short instruction. You may loose any warranty by removing the plastic backplane completely, like it is mentioned below! The first three steps are the same as described in the user’s manual for changing the batteries

  1. First unscrew the two, big bolts on the metal backplane.
  2. Now carefully shift the backplane up.
  3. You will need to open the battery latch and release the batteries. All the data will be held for about 30 minutes before getting lost.
  4. The last step is to unscrew the five little bolts and carefully shift up the plastic backplane.
  5. Attention! The beeper is sticked into the plastic backplane and connected with the calculator’s printed circuit board through very thin minus and plus cables. Don’t hesitate, otherwise you may cut the cables!
  6. Voilá!

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