Limited 12-bit Core Device Compatibility.
The ‘legacy’ 12-bit core microcontrollers have been available for a long time, and are at the heart of many excellent, and complex projects. However, with their limited architecture, they were never intended to be used for high level languages such as BASIC. Some of these limits include only a two-level hardware stack and small amounts of general purpose RAM memory. The code page size is also small at 512 bytes. There is also a limitation that calls and computed jumps can only be made to the first half (256 words) of any code page. Therefore, these limitations have made it necessary to eliminate some compiler commands and modify the operation of others.
While many useful programs can be written for the 12-bit core devices using the compiler, there will be some applications that are not suited to them. Choosing a standard or enhanced 14-bit core device with more resources will, in most instances, be the best solution, or better still, choose a suitable 18F device.
Text in this figure or table
table below: -
| Command | Reason for omission |
| Dwords | Memory limitations |
| Floats | Memory limitations |
| Signed Variables | Memory limitations |
| ADin | No internal ADCs |
| Cdata | No write modify feature |
| Cls | Limited stack size |
| Cread | No write modify feature |
| Cursor | Limited stack size |
| Cwrite | No write modify feature |
| DTMFout | Limited stack size |
| Edata | No on-board EEPROM |
| Eread | No on-board EEPROM |
| Ewrite | No on-board EEPROM |
| Freqout | Limited stack size |
No graphic LCD support LCDread
| LCDwrite | No graphic LCD support |
| HPWM | No 12-bit MSSP modules |
| HRsin | No hardware serial port |
| HRsout | No hardware serial port |
| HSerin | No hardware serial port |
| HSerout | No hardware serial port |
| Interrupts | No Interrupts |
| Pixel | No graphic LCD support |
| Serout | Limited memory |
| Serin | Limited memory |
| Sound2 | No graphic LCD support |
| UnPlot | No graphic LCD support |
| USBin | No 12-bit USB devices |
| USBout | No 12-bit USB devices |
| Plot | No graphic LCD support |
Some of the commands that are not supported for the 12-bit core devices are illustrated in the
Trying to use any of the unsupported commands with 12-bit core devices will result in the compiler producing numerous Syntax errors. If any of these commands are a necessity, then choose a comparable standard or enhanced 14-bit core device, or better still, an 18F device.
The available commands that have had their operation modified are: -
Most of the modifiers are not supported for these commands because of memory and stack size limitations, this includes the At, and the Str modifier. However, the @, Dec and Dec3 modifiers are still available.
