# Select type of CPU

The simulator supports following type of microprocessors from MCS51 family:

8051/8031
8052/8032
DS390
8051R
89C51R
80251

### 8051/8031

You can select this type of microcontroller using one of the following parameter for -t option:

- 51 (HMOS type)
- 8051 (HMOS type)
- 8751 (HMOS type)
- C51 (CMOS type)
- 80C51 (CMOS type)
- 87C51 (CMOS type)
- 31 (HMOS type)
- 8031 (HMOS type)
- C31 (CMOS type)
- 80C31 (CMOS type)

It includes core 51 features:

- 64k external RAM
- 64k ROM
- 128 byte internal RAM
- 2 timers (timer #0, timer #1)
- Serial interface
- 4 8-bit quazi bi-directional ports

CMOS types also include:

- Idle mode
- Power down mode

### 8052/8032

You can select this type of microcontroller using one of the following parameter for -t option:

- 52 (HMOS type)
- 8052 (HMOS type)
- 8752 (HMOS type)
- C52 (CMOS type)
- 80C52 (CMOS type)
- 87C52 (CMOS type)
- 32 (HMOS type)
- 8032 (HMOS type)
- C32 (CMOS type)
- 80C32 (CMOS type)

It includes same features as 8051/8031 microcontrollers and additionaly:

- 3 timers (timer #0, timer #1, timer #2)
- 256 bytes of internal RAM

### DS390

You can select this type of microcontroller using DS390 as parameter for -t option (this is a CMOS type). It includes same features as 8052 and adds:

- 24 bit flat mode
- support for dual DPTR register
- 128k external RAM
- 128k ROM
- 4k internal SRAM usable
- 10 bit stack mode
- "timed access" of SFRs

### 8051R

You can select this type of microcontroller using one of the following parameter for -t option (all are CMOS types):

- 51R
- 51RA
- 51RB
- 51RC
- C51RA
- C51RB
- C51RC

It includes all features that 8052/8032 does and additionaly:

- Extended interrupt priority system (4 priority levels)
- Extended serial line interface (automatic address recognition)
- Watchdog timer

### 89C51R

You can select this type of microcontroller using `89C51R` parameter for -t option (this CPU is always CMOS). This is a Philips clone, excluding duplicated DPTR it is similar to 8051XR from Intel.

It includes all features that 8051R does and additionaly:

- PCA (Programmable Counter Array): 5 16-bit counter, one of them can act as watchdog timer.
- Duplicated DPTR.

### 80251

You can select this type of microcontroller using one of the following parameter for -t option (all are CMOS types):

- 251
- C251

It includes all features that 89C51R does and additionaly:

- Nothing implemented yet.