Unfortunately I neither know the memory address scheme of the PC1403 – any suggestions would be appreciated – nor the ROM code. The following information was found out by try and error.
The addressing schematics look very similar to common 8 bit systems, e.g. like the Commodore 64 home computer. If so, the so called ‚zeropage‚, the first 1024 bytes of address space, should be handled carefully.
Anyway, to prevent you from inventing the wheel again, take a look!
Accessing the display
Even the display is very small (5x7x24), you can access every block on the display, and very confusing, the special functions-display.
| Bit / address | 12348 | 12349 | 12412 |
|---|---|---|---|
| 1 | Japenese symbols |
/ |
E |
| 2 | Japanese symbols |
DEF |
M |
| 3 | SML |
SHIFT |
() |
| 4 | (STAT) |
HYP |
RAD |
| 5 | (MATRIX) |
PRO |
G |
| 6 | (BASIC) |
RUN |
DE |
| 7 | left _ |
CAL |
(PRINT)_ |
To calculate the value, that needs to be poked, use: 2^(Bit-1) for setting the bit, e.g. to activate „SML“ on the display, simply use
POKE 12348,4.
As long as bit arithmetics is additive and the POKE command increases the memory address automatically, a
POKE 12348,255,255
makes your PC1403 display looking very crazy. A virus? Magic? No, not really, of course…
Password switch
Protecting your source code from foreign eyes is a nice little feature, but not very secure. Use
POKE 65300,32
to enable password protection,
POKE 65300,1
for disabling. Also look at the source section, how you can find out the whole password string.
For some source code samples, take a look at those articles.