I was looking through the microcontrollers area of Digikey and I noticed a device that i'm interested in although there is the description of "ROMLESS" in the program memory type. http://www.digikey.com/product-search/en/integrated-circuits-ics/embedded-microcontrollers/2556109?k=LPC4330

What I take away from that is that there is no flash memory internal to the chip but since it is Read-Only memory, I question that. Maybe this mean that it needs an external EEPROM to boot the program from?

So I'm not entirely sure so here I am asking:

1) What does this exactly mean


2) How would this change a design?


Actually, it's a bit of a misnomer; there is some on-chip ROM containing boot code and a small one-time-programmable (OTP) ROM for the application to use (serial numbers, configuration data, encryption keys, etc.)

But there's no on-chip nonvolatile memory for application code (it seems they wanted to use the chip area to support more SRAM instead), which means that you need to supply some other external memory (flash, SD, hard drive, etc.) to hold the application code and data. If the external device supports random addressing, you can execute code directly from it; otherwise, you can copy code into the on-chip SRAM and execute it from there.


It generally means that the device has no on-board non-volatile storage for user code. This means that the firmware must either 1) be executed directly from an external parallel device, or 2) be read into on-board RAM from an external parallel or serial device before being executed there.

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    \$\begingroup\$ It can also execute code directly from an external SPI device using the SPIFI interface. Which gives you a lot of flash for little money, and for code that needs to run fast you can copy it to the bigger internal RAM, where it runs three times faster than from internal flash. \$\endgroup\$ – starblue Apr 27 '14 at 15:45

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