News from Swiss Micros

[Christoph Giesselink]

Some words to

"Based on Saturn CPU emulation"

As the name say, we are speaking about a CPU or about a CPU core.

The Saturn CPU actually come in four flavors, three in hardware and one in software.

Generally we devide into "level 0", "level 1" and "level 2" instructions, where "level 0" only was used in the 1LF2 CPU, "level 1" instructions in the 1LK7 CPU and "level 2" in all later CPU cores like in the 1LR2. Finally we have the "level 3" instruction set in the "Saturnator", a software based CPU core emulation used the the Apple series calculators.

But a CPU makes no calculator, you need additional peripheral like "reset generation", "oszillators", "timer(s)", RAM, ROM, display (controller), display (driver) and a keyboard interface.

In the early Saturn calculators (71B, 18C, 28C) we have the physical 1LF2 or 1LK7 CPU chip and additional peripheral chips. The next and all later generations use SoC combining a CPU core with peripheral on one chip.

Lets have a look on famous Pioneer calculator generation:

We have three types of Pioneer calculators, I like to speak about the "Low End", "Mid Range" and "High End" Pioneers.

"Low End"

The "Low End" Pioneers HP-10B, HP-20S and HP-21S with the 7-segment display use the 1LU7 SoC containing the CPU core and all peripheral (oszillator, timer, RAM, ROM, display controller with display drivers, keyboard interface, ...).

"Mid Range"

The "Mid Range" Pioneers HP-14B, HP-22S, HP-32S and HP-32SII with the dot-matrix-segment display use the 1LR3 SoC containing the CPU core and all peripheral.

"High End"

The "High End" Pioneers HP-17B, HP-17BII, HP-27S and HP42S with the graphic display use the 1LR2 SoC containing the CPU core and all peripheral with the exception of "User RAM". The Display-RAM is still part of the SoC.

So calculator emulators for the Pioneers, like my Emu42, or other calculators needs a lot more than a "Saturn based CPU emulation" to run an original HP ROM image. What I don't understand, why emulating such a crippled CPU when you don't have the legal possibility to sell them with original ROM images?