| Variant | Pins | Mfg | RAM | CODE | XRAM | Notes |
| MCS251 | 40 | Intel | 1K | 16K | 0 | 16 Bit 80x51FX Prelim |
| 51C806 | 100 | Siemens | 256 | 64Kx | 64b | SIECO+CAN+appx 517A, faster |
| 80C537A | 84 | Siemens | 256 | 64Kx | 2K | ALU, 8 PWM, CaptComp 2UART, 10b A/D |
| 80C517A | 84 | Siemens | 256 | 32K | 2K | ALU, 8 PWM, CaptComp 2UART, 10b A/D |
| 80537 | 84 | Siemens | 256 | 64Kx | 0 | ALU, 8 PWM, CaptComp 2UART, 10b A/D |
| 80517 | 84 | Siemens | 256 | 8K | 0 | ALU, 8 PWM, CaptComp 2UART, 8b A/D |
| 73D2910 | 100qf | SSI | 256 | 128Kx | 0 | 80C52+Ports+HDLC |
| 80C535A | 68 | Siemens | 256 | 64Kx | 1K | 515+10bA/D, 1K XRAM, BRG, OWD |
| 80CE558 | 80qfp | Philips | 256 | 64Kx | 768 | Enhanced 80C552, Sep i2c, RSO |
| 80C515A | 68 | Siemens | 256 | 32K | 1K | 515+10bA/D, 1K XRAM, BRG, OWD |
| 80535 | 68 | Siemens | 256 | 64Kx | 0 | Timer2, CaptComp, 6 ports, 8/10b A/D |
| 80515 | 68 | Siemens | 256 | 8K | 0 | Timer2, CaptComp, 4 ports, 8b A/D |
| 80C535 | 68 | Siemens | 256 | 64Kx | 0 | Timer2, CaptComp, 5 ports 8b A/D |
| 80C51GB | 68 | Intel | 256 | 64Kx | 0 | 8051FA+PCA, 8b A/D, SPI |
| 87C51GB | 68 | Intel | 256 | 8K | 0 | 8051FA+PCA, 8b A/D, SPI |
| 80C592 | 68 | Philips | 256 | 64Kx | 256 | 552-i2c+CAN+XRAM |
| 87C592 | 68 | Philips | 256 | 16K | 256 | 552-i2c+CAN+XRAM |
| 87C598 | 80 | Philips | 256 | 32K | 256 | 552-i2c+CAN+XRAM |
| 80C552 | 68 | Philips | 256 | 64Kx | 0 | 10b A/D, i2c, CaptComp, PWM |
| 87C552 | 68 | Philips | 256 | 8K | 0 | 10b A/D, i2c, CaptComp, PWM |
| 80C562 | 68 | Philips | 256 | 64Kx | 0 | 8b A/D, i2c, CaptComp, PWM |
| 87C451 | 68 | Philips | 128 | 4K | 0 | 7 Ports, 1 Handshake |
| 80C451 | 68 | Philips | 128 | 64Kx | 0 | 7 Ports, 1 Handshake |
| 87C453 | 68 | Philips | 256 | 8K | 0 | 7 Ports, 1 Handshake |
| 83CL580 | 56,64 | Philips | 256 | 6K | 0 | LV 8052+ADC+i2c+More INTs, WDOG |
| SABC503 | 44 | Siemens | 256 | 64Kx | 0 | 80C52+8Ch, 10bA/D, BRG, WD, OWD |
| 80C320 | 40 | Dallas | 256 | 64Kx | 0 | FAST, 2 DPTR 2 UART VRST |
| 80C310 | 40 | Dallas | 256 | 64Kx | 0 | Simpler 80C320 e62Mhz |
| 87C520 | 40 | Dallas | 256 | 16K | 1K | 16K OTP enhanced 80C320 |
| 80C51FX | 40 | Intel | 256 | 64Kx | 0 | 80C58i+PCA, AsRST |
| 87C51FA | 40 | Intel | 256 | 8K | 0 | 8052+PCA, Enh Serial, Automotive |
| 87C51FB | 40 | Intel | 256 | 16K | 0 | 8052+PCA, Enh Serial, Automotive |
| 87C51FC | 40 | Intel | 256 | 32K | 0 | 8052+PCA, Enh Serial, Automotive |
| 8XC51FB | 40 | Philips | 256 | 16K | 0 | 87C51FB with ALE RFI mode |
| 87C51FX | 40 | Intel | 256 | 32K | 0 | 3v3 80C51FC |
| 80C152J | 68 | Intel | 256 | 64Kx | 0 | HDLC/SDLC Serial |
| 80C152 | 48 | Intel | 256 | 64Kx | 0 | SDLC Serial |
| 8044 | 40 | Intel | 192 | 64Kx | 0 | RUPI Serial |
| 80C575 | 40 | Philips | 256 | 64Kx | 0 | 8052+PCA, AnalogComp, WDOG, RSTLo |
| 87C575 | 40 | Philips | 256 | 8K | 0 | 8052+PCA, AnalogComp, WDOG, RSTLo |
| 80C576 | 40 | Philips | 256 | 8K | 0 | 8052+PCA, UPI, A/D, PWM, WDOG, VRSTLo |
| 87C576 | 40 | Philips | 256 | 8K | 0 | 8052+PCA, UPI, A/D, PWM, WDOG, VRSTLo |
| SABC501 | 40 | Siemens | 256 | 64Kx | 0 | 40MHz Enhanced 8052 U/D |
| SABC502 | 40 | Siemens | 256 | 64Kx | 256 | 8052+XRAM+8DP+WD+BRG+OWD |
| 80C528 | 40 | Philips | 256 | 64Kx | 256 | 8052+Wdog, XRAM |
| 87C528 | 40 | Philips | 256 | 32K | 256 | 8052+Wdog, XRAM |
| 89CE528 | 44 | Philips | 256 | 32KF | 256 | Flash 528 |
| 87C524 | 40 | Philips | 256 | 16K | 256 | 16K 87C528 |
| 80C550 | 40 | Philips | 128 | 4K | 0 | 8b A/D WDog |
| 80CL781 | 40 | Philips | 256 | 64Kx | 0 | Low Voltage 8052, More INTs, WDOG |
| 83CL781 | 40 | Philips | 256 | 16K | 0 | Low Voltage 8052, More INTs, WDOG |
| 80CL782 | 40 | Philips | 256 | 64Kx | 0 | Low Voltage, faster 781 |
| 89C52 | 40,44 | Atmel | 256 | 8KF | 0 | FLASH, Fast,LV 87C52 |
| 87C54 | 40 | Intel | 256 | 16K | 0 | 16K 87C52i |
| 87C58 | 40 | Intel | 256 | 32K | 0 | 32K 87C52i |
| 87C52 | 40 | Intel | 256 | 8K | 0 | 8052+U/D+OscO+4Li |
| 80C154 | 40 | Matra | 256 | 64Kx | 0 | Enhanced 8052 (also OKI) |
| 83C154D | 40 | Matra | 256 | 32K | 0 | Enhanced 8052 |
| 83C154 | 40 | OKI | 256 | 16K | 0 | Enhanced 8052 |
| 80C654 | 40 | Philips | 256 | 64Kx | 0 | i2c |
| 87C652 | 40 | Philips | 256 | 8K | 0 | i2c |
| 87C654 | 40 | Philips | 256 | 16K | 0 | i2c |
| 83CE654 | 44qfp | Philips | 256 | 16K | 0 | i2c, low RFI 654 |
| DS5000 | 40 | Dallas | 128 | 32KR | 32K | 80x51 Secure + NV support, BootLdr |
| DS2250 | 40sim | Dallas | 128 | 32K | 32K | As 5000, but smarter package |
| DS5001 | 80qfp | Dallas | 128 | 64Kx | 64K | Better 5000, + RPC + BatSw |
| 80C851 | 40 | Philips | 128 | 64Kx | 0 | 8051+256B EEPROM |
| 83C852 | 6 | Philips | 256 | 6K | 0 | 2K EEPROM SmartCard 80x51, Die, ALU |
| 8052 | 40 | All | 256 | 64Kx | 0 | 8051+Timer2 |
| 8752 | 40 | Intel | 256 | 8K | 0 | 8051+Timer2 |
| 80C52 | 40 | Siemens | 256 | 64Kx | 0 | 8051+Timer2, Philips, Oki, Matra |
| 88SC54C | 8 | Atmel | 256 | 64Kx | 512 | 8052+PublicKey,prelim |
| 80CL410 | 40 | Philips | 128 | 64Kx | 0 | Low Voltage, More INTs, i2c-UART |
| 80CL31 | 40 | Philips | 128 | 64Kx | 0 | Low Voltage, More Ints, 80x51 |
| 80CL610 | 40 | Philips | 256 | 64Kx | 0 | Low Voltage, More INTs, i2c-UART |
| 83CL411 | 40 | Philips | 256 | 64Kx | 0 | 80CL31 with 256 RAM, No T2 |
| 89C51 | 40,44 | Atmel | 128 | 4KF | 0 | FLASH,Fast,LV 87C51 |
| 8751 | 40 | All | 128 | 4K | 0 | Core processor, UART, Tmr0, Tmr1 |
| 87C51 | 40 | All | 128 | 4K | 0 | Core processor, UART, Tmr0, Tmr1 |
| 8031 | 40 | All | 128 | 64Kx | 0 | Core processor, UART, Tmr0, Tmr1 |
| 8051 | 40 | All | 128 | 4K | 0 | Core processor, UART, Tmr0, Tmr1 |
| 80C31L | 40 | Matra | 128 | 64Kx | 0 | Low Voltage 80x51 |
| 87C752 | 28 | Philips | 64 | 2KE | 0 | 87751+ A/D, PWM |
| 87C749 | 28 | Philips | 64 | 2KE | 0 | 87C752 - i2c |
| 87C751 | 24 | Philips | 64 | 2KE | 0 | Small size, bit i2c |
| 87C748 | 24 | Philips | 64 | 2KE | 0 | 87C751 - i2c |
| 87C750 | 24 | Philips | 64 | 1KE | 0 | Small size, |
| 89C2051 | 20 | Atmel | 128 | 2KF | 0 | 20Pin 89C51,+AnaComp+LED |
| 89C1051 | 20 | Atmel | 64 | 1KF | 0 | 20Pin 2051 -uart,timer1 |