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.

17. Revised on Feb. 03, 2024

    Added a video and the project link of 'Telescope Mount Controller using PERSEUS-9' to Chapter 10.

18. Revised on Apr. 22, 2024

    Modified the circuit of the enable input pin 6 of address decoder IC36 from fixed H logic to the CPU reset signal to prevent the RAM from going into the active state during the power shutdown sequence. 

    Changed the schematic in the attached file to the Jan. 5, 2024 version, applying MOD 1 above.