I am interested in "old" electronics and without any project in mind I was wondering if there is a MCU directly compatible with 4000 series of CMOS logic.
When you have 12V system it makes sense and simplifies the design to have a MCU able to directly interface the signals. Of course 12 V systems are obsolete now but in the past they were common and so I have expeted to find something suitble. After a lot of searching I have found only the MC14500B single-bit "ICU" (Industrial Control Unit) - surely interesting on its own. It has 3 - 18 V operation which is the voltage range of CMOS 4000 series logic. The Wiki says this device was manufactured until 1990s implying it has seen some use. It is more a CPU instead of a MCU (it needs external ROM and RAM). But I did not manage to find any memory working with such "high" voltages. Example applications of the MC14500 use standard 5 V RAM and ROM chips.
Is there any true 12 V MCU?
Is there some 12 V memory that could be used to store the program for MC14500 to make a 12 V only system or is it simply a feature that was never used?
Nope; you're gonna need level shifters. The market is too small - for devices that would be a level shifter and an MCU in one package, - that there aren't any available to my knowledge. The needs of people in the market for those kind of things are also different enough from eachother that a one-size-fits-all HV microcontroller wouldn't be likely to be a commercial success.
These days, even stuff like the latest 8-bit AVRs (the AVR Dx-series - they're what probably would have been the megaAVR 1-series (upmarket successor to the 0-series like the 4809 used in Nano Every) had Microchip not taken the "ATmega" branding out behind the woodshed), while they run at "1.8-5.5 volts"... are actually not running the core at 5v... there's a voltage regulator on chip that produces the required Vcore, which is why they can run at their full rated speed even at the minimum voltage
Smajdalf:
I am interested in "old" electronics and without any project in mind I was wondering if there is a MCU directly compatible with 4000 series of CMOS logic.
When you have 12V system it makes sense and simplifies the design to have a MCU able to directly interface the signals. Of course 12 V systems are obsolete now but in the past they were common and so I have expeted to find something suitble. After a lot of searching I have found only the MC14500B single-bit "ICU" (Industrial Control Unit) - surely interesting on its own. It has 3 - 18 V operation which is the voltage range of CMOS 4000 series logic. The Wiki says this device was manufactured until 1990s implying it has seen some use. It is more a CPU instead of a MCU (it needs external ROM and RAM). But I did not manage to find any memory working with such "high" voltages. Example applications of the MC14500 use standard 5 V RAM and ROM chips.
Is there any true 12 V MCU?
Is there some 12 V memory that could be used to store the program for MC14500 to make a 12 V only system or is it simply a feature that was never used?
Market pressure has ALWAYS called for more speed. True back then and the same is true today. More speed means lower voltages, not higher.
Paul
There was the RCA CDP1802. An early CMOS microProcessor and associate support chips that would run at higher voltages. It gained some popularity because a core system was small and cheap (relatively speaking), and it still generates some interest among “vintage computer” folk. Cf “COSMAC Elf”
