First things first,I am a total newbie to the 8051 MCU. I want to get started with 8051 MCU (At89s52). I've got the compiler and all (sdcc),now all I need is a bootloader.However I can't find one,Do I need to create my own or is there any pre existing bootloaders

  • \$\begingroup\$ Why do you need a bootloader? Are you trying to download programs over serial or other medium? \$\endgroup\$
    – Ron Beyer
    Oct 2, 2017 at 15:12
  • \$\begingroup\$ Do you understand what a bootloader is for? \$\endgroup\$ Oct 2, 2017 at 15:14
  • \$\begingroup\$ I suggest you to start with few blinking LEDs \$\endgroup\$
    – Eugene Sh.
    Oct 2, 2017 at 15:17
  • \$\begingroup\$ Yeah I know what bootloaders are for,I am not an expert,it's just that while my time using avr you had avrdude to flash programs ,the same thing here. \$\endgroup\$
    – Dr.Topaz
    Oct 2, 2017 at 15:19
  • \$\begingroup\$ So what do you need the bootloader for? Do you have a board with USB or some other interface you want to be able to upload programs with? \$\endgroup\$
    – Eugene Sh.
    Oct 2, 2017 at 15:21

1 Answer 1


After reset (either a hard reset or an instruction reset) the program counter returns to 00h. Whatever instruction is located there then gets loaded into the processor.

This is dependent on what kind of I/O (or system architecture) you have attached to the processor. If you have a ROM attached (with the enable lines configured right) then it will load the instruction from 00h into the processor and start your program or OS on the ROM.

With the At89s52 you need to program the ROM

  • \$\begingroup\$ Looking for a more simpler way, \$\endgroup\$
    – Dr.Topaz
    Oct 2, 2017 at 15:32
  • \$\begingroup\$ You have to load whatever program into the ROM, there is no 'simpler' way. There is nothing 'automatic' about an 8051, its one of the first mainstream processor cores and 27 years old. \$\endgroup\$
    – Voltage Spike
    Oct 2, 2017 at 15:36
  • \$\begingroup\$ @laptop2d - more like 37 years (first released 1980). \$\endgroup\$
    – Dave Tweed
    Oct 2, 2017 at 15:46
  • \$\begingroup\$ The key to writing a bootloader is whether or not the particular chip in question can write to its own flash memory. If not, there's no way to write a bootloader for it. \$\endgroup\$
    – Dave Tweed
    Oct 2, 2017 at 15:48
  • \$\begingroup\$ Yep 37, wow, time files \$\endgroup\$
    – Voltage Spike
    Oct 2, 2017 at 15:52

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