1. The article was first posted on Jul. 23, 2022.

2. Revised on Aug. 11, 2022

    Added the parts location figure and a memory dump program by using CI-2 in the attachment. 

3. Revised on Aug. 22, 2022

    For ease of reading, the chapter 3 "hardware configuration" was divided into "3. Dual CPU hardware configuration," , "4. Peripheral devices," and "5. Component placement,". and the chapter 5 "System software" was divided into, "7. System software configuration" and "8. Terminal section system software. 

4. Revised on Aug. 25, 2022

    Added the video 2 as an example user program that accesses AD converter connected to the parallel interface of PERSEUS-9.

    And added the example user program ADC_02.pdf to the attachment.

5. Addition on Sep. 14, 2022

    A photo of the switches on the right side of the enclosure and a photos of the test situation during board making were added to the attachment.

6. Revised on Sep. 16, 2022

    Added description of memory configuration in Chapter 3 "Dual CPU hardware configuration".

    Added description of serial and parallel interfaces in the main CPU section to Chapter 4 "Peripheral devices".

    Replaced the memory dump program MEM_DUMP_03.TXT in the attached file with MEM_DUMP_04.TXT, which allows hexadecimal input of start addresses.

7. Revised on Sep. 22, 2022

    Added to Chapter 9 "Results" that CI-2 on PERSEUS-9 could perform elementary function calculations, line number editing, FFT, etc. as on PERSEUS-8.

8. Revised on Sep. 24, 2022

    Linked a new explanatory video to "input and modification of user programs" in Chapter 9 Results.

9. Revised on Sep. 28, 2022

    Added the video 3 as "Simple programming example on PERSEUS-9" in Chapter 9 Results.

10. Revised on Nov. 28, 2022

    Added the video 4 as "Loading a program from an external PC terminal, and execution of its program to calculate the position of the planet."  in Chapter 9 Results.

11. Revised on Feb. 27, 2023

    Added video link to 'simple serial terminal' in chapter 4 Peripheral devices.

12. Revised on Mar. 14, 2023

    Added Fig.5.1 of a homemade PROM programmer connected parallel interface in chapter 4 Peripheral devices.

13. Revised on Mar. 20, 2023

    Added a link for video to introduce updating CI-2 the interpreter by using a homemade PROM programmer for Chapter 7.

14. Revised on Mar. 24, 2023

    Added a link for the schematic of a homemade PROM programmer in Chapter 4.

15. Revised on Apr. 28, 2023

    Added Figure 5.2 of PROM module EXTROM-2 in chapter 4 Peripheral devices.

    Added description of user program loading by the ROM module in chapter 9 Results.

16. Revised on Aug. 01, 2023

    Added Chapter 9 "Program loading", and added a link of codes of the interpreter CI-2 version 2.0.0.