Intel Hex question - UK Vintage Radio Repair and Restoration Discussion Forum

Jon_G4MDC · 5th Aug 2023, 4:41 pm

I hope this is a simple question for the experts on Intel Hex file format.

It is well explained in a number of sources. Lines always start with a colon : followed by the number of bytes in the line etc....

I have a file which has a header with a text description, the creation date, last editing date etc. These lines all start with a semi-colon ; instead of :

My question, does the fact that a line starts with something other than a colon mean the line is simply ignored? I don't have any other examples to compare with.

TIA

paulsherwin · 5th Aug 2023, 4:51 pm

I think it's a comment delimiter.

ortek_service · 5th Aug 2023, 4:54 pm

; is only a recognised comment prefix in certain programming languages, so it isn't too universal.

But from previous issues / discussions we had about this on here, it seems the original Intel Hex standard was to ignore any text etc. that wasn't a valid header at the start of a line (And paper-tape readers were often used, so there wasn't always a clear start until this header was found).

However, more recently, many PC etc. file import programs have not been expecting any text etc at the start of the file, so have failed. And it was necessary to manually remove it, before loading the file into the software.
Although, the latest version of HxD (Version 2.5.0.0 2021), should now at least work OK with files that have extra text lines.

Jon_G4MDC · 5th Aug 2023, 4:57 pm

That makes sense. It certainly looks like it has been used that way.

In this case it is in a data file going between a PC program and a serial programmer. All developed by the same company (Marconi) and not with any need to communicate with other manufacturers gear. I suppose they could do what they like.

Certainly the main data block is Intel format. I think if uploading to some other EPROM programmer, as I need to do, leaving out the lines starting ; might be best.

ortek_service · 5th Aug 2023, 5:37 pm

Well you can try and see what the EPROM Programmer makes of it - It'll hopefully give an error if it doesn't like it (I think with some Dataman PC-based IC-programmers, it notifies you it has found an issue / that it has ignored the extra lines).
If the programmer gives a checksum, then you can compare it with that generated by Importing file into HxD / uploading a file without the extra lines.
Older, self-contained with serial upload link programmers should hopefully conform to the original standard that it seems many PC programmers weren't aware of.

Jon_G4MDC · 5th Aug 2023, 5:45 pm

Thanks for all the help. This exercise somewhat hindered by the fact that my only EPROM programmer needs to be in an ISA slot!

It's a bit of a thought experiment for now which might get tested by others.

5th Aug 2023, 4:41 pm	#1
Jon_G4MDC Nonode Join Date: Nov 2015 Location: Welwyn Garden City, Hertfordshire, UK. Posts: 2,015	Intel Hex question I hope this is a simple question for the experts on Intel Hex file format. It is well explained in a number of sources. Lines always start with a colon : followed by the number of bytes in the line etc.... I have a file which has a header with a text description, the creation date, last editing date etc. These lines all start with a semi-colon ; instead of : My question, does the fact that a line starts with something other than a colon mean the line is simply ignored? I don't have any other examples to compare with. TIA

5th Aug 2023, 4:51 pm	#2
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,943	Re: Intel Hex question I think it's a comment delimiter.

5th Aug 2023, 4:54 pm	#3
ortek_service Octode Join Date: May 2018 Location: Northampton, Northamptonshire, UK. Posts: 1,440	Re: Intel Hex question ; is only a recognised comment prefix in certain programming languages, so it isn't too universal. But from previous issues / discussions we had about this on here, it seems the original Intel Hex standard was to ignore any text etc. that wasn't a valid header at the start of a line (And paper-tape readers were often used, so there wasn't always a clear start until this header was found). However, more recently, many PC etc. file import programs have not been expecting any text etc at the start of the file, so have failed. And it was necessary to manually remove it, before loading the file into the software. Although, the latest version of HxD (Version 2.5.0.0 2021), should now at least work OK with files that have extra text lines.

5th Aug 2023, 4:57 pm	#4
Jon_G4MDC Nonode Join Date: Nov 2015 Location: Welwyn Garden City, Hertfordshire, UK. Posts: 2,015	Re: Intel Hex question That makes sense. It certainly looks like it has been used that way. In this case it is in a data file going between a PC program and a serial programmer. All developed by the same company (Marconi) and not with any need to communicate with other manufacturers gear. I suppose they could do what they like. Certainly the main data block is Intel format. I think if uploading to some other EPROM programmer, as I need to do, leaving out the lines starting ; might be best.

5th Aug 2023, 5:37 pm	#5
ortek_service Octode Join Date: May 2018 Location: Northampton, Northamptonshire, UK. Posts: 1,440	Re: Intel Hex question Well you can try and see what the EPROM Programmer makes of it - It'll hopefully give an error if it doesn't like it (I think with some Dataman PC-based IC-programmers, it notifies you it has found an issue / that it has ignored the extra lines). If the programmer gives a checksum, then you can compare it with that generated by Importing file into HxD / uploading a file without the extra lines. Older, self-contained with serial upload link programmers should hopefully conform to the original standard that it seems many PC programmers weren't aware of.

5th Aug 2023, 5:45 pm	#6
Jon_G4MDC Nonode Join Date: Nov 2015 Location: Welwyn Garden City, Hertfordshire, UK. Posts: 2,015	Re: Intel Hex question Thanks for all the help. This exercise somewhat hindered by the fact that my only EPROM programmer needs to be in an ISA slot! It's a bit of a thought experiment for now which might get tested by others.