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How to use romprg (on a NEC V25 ELKS system)

What is romprg?
On embedded devices the ELKS system firmware usualy resides in a flash 
memory chip (ROM for short) and may contain the system BIOS or startup 
code, the ELKS operating system and/or the ROM filesystem for booting ELKS. 

romprg is a client server utilyty tool for system builders to program
the ELKS system firmware in a running ELKS 8018x-system. It was ported
to ELKS from https://github.com/tehKaiN/ROMprg by git user cocus 
(Santiago Hormazabal) and adapted by me, swausd, for using on
a NEC V25 ELKS system.

romprg was designed to program 29Fxxx flash ROMs. I have verified that
it works for SST39SF040 types too. I use romprg with serial baud rate set
to 115200 baud.

For the "in system programming" to work you have to have a running ELKS 
system with the ROM integrated into the systems address space. Starting 
address of the flash for now is fixed in the source code flash.c to 0x8:0000


Requirements:
A working serial connection between the ELKS system and the PC is needed.
This conection is configured at compile-time of romprg and hostromprg.
See version.h and main.c in the romprg source folder.

Start romprg on ELKS (the server). romprg now waits for commands like
live check, erase ROM or read/erase/write ROM from the client (hostromprg
on the PC) and executes these commands.

Attention:
You should know what you are doing, for exaple how sectors of the flash 
are organized. Otherwise you may end with an ELSK system without a 
functional firmware!
So please think twice before doing anything ;-)


Example workflow to get a new romfs.bin into my embedded ELKS:

'#' mark commands on the ELKS command shell
'>' mark commands on the PC command shell

Working directory for this example is ./elks/elkscmd/romprg

Connection to the ELKS system is via PC terminal emulation using the serial
port console which is also configured for using with romprg.

1. Start romprg on the ELKS system, for example from SD card:

# romprg
Flash program, build on Thu Nov 13 18:28:57 2025

Attention: On NEC V25 0xf:fe00 - 0xf:ffff cannot be programmed with romprg!
           This is the MCU internal RAM/IO address space.

Exit the terminal emulation now and start the host programmer client...

2. Exit the PC terminal emulation session, because romprg now is using the
connection exclusively until to the next ELKS reboot.
To manage flashing, enter hostromprg-commands on the PC command shell.

3. Live check the connection between ELKS and the PC by
specifying the used <serial port device name> and the command <ping>:
> ./hostromprg /dev/ttyUSB0 ping
Firmware version:   1.02
  address bits:       18
  max write length:  128

4. Delete the part of the flash memory which is to be re-programmed by
specifying <relative start-address in ROM> and <relativ end-address-1 in ROM>:
> ./hostromprg /dev/ttyUSB0 erase 0x00000 0x60000

5. Write image file to flash by specifying <relative start-address in ROM> 
and <filename with binary data>:
> ./hostromprg /dev/ttyUSB0 write 0x00000 ../../image/romfs.bin 
Writing 0x0xxxxx-0x05cc68

6. Read programmed ROM to verify programming by specifying 
<relative start-address in ROM>, <relativ end-address-1 in ROM> and
<filename of read data>:
> ./hostromprg /dev/ttyUSB0 read  0x00000 0x5cc69 rom.bin
Reading 0x0xxxxx-0x05cc68

7. Compare the two files using linux diff to show any differences:
> diff ../../image/romfs.bin ./rom.bin

8. Reboot the ELKS system.

14. Nov. 2025 swausd
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