C Compiler package (incl. CA78K0R, CA78K0) for RL78 and 78K Families is intended for the development of ROM-based systems for embedded applications. In addition to powerful optimization functions that help boost code efficiency and speed up program execution, this package provides extension functionality to support a broad range of embedded devices.

For RL78 Family Users; New compiler package "C Compiler Package for RL78 Family (CC-RL)" also available. Assistance in Porting Files to the CC-RL from the CA78K0R and CA78K0, please refer to Assistance in Porting Files to the C Compiler Package for RL78 Family.
For 78K Family Users; Please use this product (CA78K0R, CA78K0).


  • ANSI-compliant
    • Supports C89 and C99 (subset of functions (For example, // comments)).
  • Superior optimization
    • Optimization for reducing the size or speed of executable code is available.
    • A multitude of optimization functions are easily accessible via the GUI.
  • Interoperation with RL78, 78K0R and 78K0 architectures
    • Interrupt handling can be accomplished by writing code in C.
    • A variety of interrupt functions are provided.
  • Development to match the usage application
    • Supports Renesas IDE, CS+.
    • Also supports execution from the command line.
  • Learn More

Release Information

Product Name Version / Release Date Note
C Compiler and IDE for RL78/78K Family Ver.: CS+ V8.09.00
(CS+ for CA,CX V4.08.00)
Released: Jan 20, 2023
Compiler: CA78K0R (for RL78 and 78K0R)
Latest Ver.: V1.72
Released: Mar 7, 2016

Compiler: CA78K0 (for 78K0)
Latest Ver.: V1.30
Released: Nov 1, 2012
  1. Update CS+ if you are not already using the latest version.


What are the advantages of using different memory models?
Supported character codes_CA78K0R
Load Module File Format (CA78K0R and CA78K0)

See all related FAQs

Target Devices (Target Families)

Target Devices


Title Type Date
ZIP63 KB日本語
Upgrade - Compiler
EXE18.81 MB日本語
Upgrade - Compiler

Synergy Download


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Application Note
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Manual - Development Tools
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Release Note
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Tool News - Note
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Additional Details

Product Lineup

Product Name IDE Part Number
C Compiler and IDE for RL78/78K Family (Note1) CS+(Note2) R0C07800QSW01N(Note3)

When ordering, please contact your local Renesas Electronics marketing office or distributor.

  1. This product is different from the C compiler package for RL78 family (CC-RL).
  2. CS+ is not promoted in America and Europe. Please contact your regional marketing/sales team for information.
  3. This part number is for ordering single license.
    To order 5-, 10-, and 20-license products, append #L5, #LA, and #LT, respectively, to the end of the part number.

Product Components

  • CS+ for CA,CX Common Program (with the debugging function)
  • Compiler/Assembler/Linker (CA78K0R, CA78K0)
  • Simulator
  • Device Information
  • CS+ Utilities
  • Emulator Utilities
  • USB Driver
  • Update Manager
  • Stack Usage Tracer
  • Variables/Functions Information File Generator (targets: RL78 family and 78K0R)
  • Variables Information File Generator (target: 78K0)
  • Memory Bank Relocation Support Tool (target: 78K0)



CS+ for CA,CX

Note that simply entering the license key printed on a purchased compiler package upgrades to the commercial edition, so you don’t have to re-install CS+ from scratch.
For more information, refer to the License information on the CS+ Information for Users.

Product Updates

Online updates are available via the CS+ Update Manager.
We recommend using the latest version.

Device Information

You can add the support devices by updating the Device Information (DevInfo_RL78, DevInfo_78K).


The CA78K0R Compiler and CA78K0 Compiler are included in the C Compiler package for the RL78 and 78K Families (for CS+) and is not available separately.
When ordering, please contact your local Renesas Electronics marketing office or distributor.