How to reduce the size of a gmapsupp.img file on a card???

**Butters** · 5th September 2017, 12:00 AM

MapSource was great for making custom sized images from earlier versions of PC Data however sadly it's been discontinued and unsupported by Garmin for several years now. The more advanced algorithm used by MapInstall is far better suited for making modern NT img files. You can often see yourself that the two programs work differently by using each for compiling maps with the same tiles, the resultant img files aren't identical when compared. The tiny errors may go unnoticed or they may cause navigation errors or even make the device crash or freeze. More recent devices seem to be particularly sensitive to images made with MS, older devices seem more tolerant in my anecdotal experience but it's not worth the risk so better to use MI exclusively for making images. Quite ok to use MS for other purposes however and in some ways it's easier and more comfortable to use than BaseCamp.

Regarding the comment "use a 4gb card which allows for slightly larger mapsets", this is simply because 2GB (gigabyte) cards are usually measured by the manufacturer in the decimal form, ie. factor of 1000. Generally, CF cards are slightly higher capacity than SD cards but most CF cards only have usable capacity of a bit over 2,000,000,000 bytes, ~2 gigabytes (decimal). However when using the original binary form of gigabyte, now more correctly called gibibyte, that's only ~1.9 GiB as actually 2 GiB has 2,147,483,648 bytes. Both Microsoft and Garmin continue to use the binary form (factor of 1024) when referring to GB and the FAT16 files size limit is 2 gibibytes minus one byte: 2,147,483,647 bytes. Just as a "2 GB" card doesn't actually have all of the 2 billion bytes nominally available because of some space already used for hard coded info, neither does a "4 GB" card have all 4,294,967,296 bytes either but it can certainly accommodate a file up to the full FAT16 limit of 2,147,483,647 bytes. The 4GB card can be left as the factory default format of FAT32 or reformatted as FAT16 for use with the StreetPilot 26x0 based GW navi 2006-08. This is a "2GB" Sandisk CF card containing a single large gmapsupp.img file:

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**jinxxxxxx** · 5th September 2017, 12:45 AM

As far as MS v MI i will play and see if I find any differences.

Now you try this . Put all of the USA on any some of Canada on a 4gb cf card. the file size should be around 2,040,000,000b according to MS or MI. Put it in your goldwing and see if it works. Do an address find,if the address find works than the mapset is fine. If not reduce it to 2.03gb Now try putting that same img on your 2gb CF. Surprise surprise it wont fit. If you use a 4gb CF card you can load a mapset that is about 200 to 300mb larger than if it is on a 2gb card.

It seems that the goldwings that use the CF card can actually read a 2,040,000,000 b file and read a card as larger as 32gb.
Now it would be nice if Garmin would update the FW to read larger file sizes.

**Butters** · 5th September 2017, 06:15 AM

Originally Posted by jinxxxxxx

As far as MS v MI i will play and see if I find any differences.

Compare the img files in HexCmp.

Now you try this . Put all of the USA on any some of Canada on a 4gb cf card. the file size should be around 2,040,000,000b according to MS or MI. Put it in your goldwing and see if it works. Do an address find,if the address find works than the mapset is fine. If not reduce it to 2.03gb Now try putting that same img on your 2gb CF. Surprise surprise it wont fit. If you use a 4gb CF card you can load a mapset that is about 200 to 300mb larger than if it is on a 2gb card.

I don't know if you fully got what I was saying about gigabyte vs. gibibyte. To briefly reiterate, a 2GB CF card has something over 2 billion bytes available, the Sandisk in the Post #11 pic has total capacity of 2,047,541,258 bytes so one of 2,040,000,000 bytes will definitely fit ok on it. Look at the img size on that CF in the pic, it's even bigger at 2,044,526,592 bytes and it works just fine. I think your reference to 2.03GB is actually GiB (binary) which is ~2,179,695,900 B so it won't fit on a 2GB CF. A file of 2.03GB (decimal) is ~2,030,000,000 bytes so it will fit. It's so confusing with MS using the original binary form for gigibyte and drive manufacturers using the decimal form. This explains the history:

Code:

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It seems that the goldwings that use the CF card can actually read a 2,040,000,000 b file and read a card as larger as 32gb.

As said they can read a file not exceeding 2,147,483,647 bytes and can probably read from a CF larger than 32GB provided it's formatted in FAT32 not exFAT.

Now it would be nice if Garmin would update the FW to read larger file sizes.

That would be nice, but I'll bet they won't bother. It's only a few lines of code to add to an updated firmware, they did it for about 5 years back for US/EU nuvi 7xx and 2xx but not for any earlier devices. I think if they were going to do it for the 06-08 GW navi they'd have done it at latest in Firmware Version 4.50 when they added NT capability.

**jinxxxxxx** · 5th September 2017, 03:53 PM

I fully understand more tha you know. Sadly you don,t know what you are saying.

I don't know if you fully got what I was saying about gigabyte vs. gibibyte. To briefly reiterate, a 2GB CF card has something over 2 billion bytes available, the Sandisk in the Post #11 pic has total capacity of 2,047,541,258 bytes so one of 2,040,000,000 bytes will definitely fit ok on it. Look at the img size on that CF in the pic, it's even bigger at 2,044,526,592 bytes and it works just fine. I think your reference to 2.03GB is actually GiB (binary) which is ~2,179,695,900 B so it won't fit on a 2GB CF. A file of 2.03GB (decimal) is ~2,030,000,000 bytes so it will fit. It's so confusing with MS using the original binary form for gigibyte and drive manufacturers using the decimal form. This explains the history:

Noway will a 2,040,000,000 bytes file fit on a 2gb card.

Now who gives a **** how much memory a card can hold if it can't hold your file. If you wish to limit yourself to 1.87 gb file size be my quest.
If you wish to limit yourself to 2014 mapset be my quest.

Just remember according to you and your explanation you can't put a 2147483647 file on a 2gb card. But I can put it on a 4,8,16,32 gb card. So stop wasting peoples time.

When quoting another post, please use [QUOTE] tags to make that clear. I've added them above to make it clear you were partly quoting from another post. Also please resist using any wording that may be construed as personal denigration.

**Butters** · 5th September 2017, 11:26 PM

No need to be that way. I do know what I'm saying and it's not just opinion, it's science and mathematics. You can remain stubborn or look again at my previous posts, personally I don't give a **** either but I do care about not creating even more confusion for readers of this forum. Every thing I've said is fact and backed up with evidence. That's shaken your opinion and anecdotal experience but that's no justification to simply attack me contrary to the facts. Read on if you want, or not, jinxxxxxx, either way I don't care. But the last thing I want to do is allow the confusion over binary and decimal forms of 'kilo' to fester. There is no justification for this statement:

Noway will a 2,040,000,000 bytes file fit on a 2gb card.

Clearly it will fit because an even larger img file fits on my '2gb' card. Maybe less words and more pictures will help with understanding:

2 GB CF 1

Source of above:

Code:

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About this statement:

If you wish to limit yourself to 1.87 gb file size be my quest.

Certainly you may have a CF card limited to '1.87gb', by which I guess you mean 1.87 gibibytes and that's only around 2,008,000,000 bytes so a file of 2,040,000 B won't fit. Certainly capacities of cards vary depending on the manufacturer. I've got SD and microSD '2GB' cards which vary between 1.84 and 1.87 GiB effective capacity. The indisputable point is that my Sandisk 2GB CF's have ~1.90 GiB.

If you wish to continue a discussion factually with dignity and politeness jinxxxxxx then please respond if you'd like more info or clarification. Otherwise I'll not contribute further to this.

**osiris4isis** · 5th September 2017, 11:45 PM

"The gigabyte (/ˈɡɪɡəbaɪt/ GIG-ə-byt or /ˈdʒɪɡəbaɪt/[1]) is a multiple of the unit byte for digital information. The prefix giga means 10^9 in the International System of Units (SI). Therefore, one gigabyte is 1000000000bytes. The unit symbol for the gigabyte is GB.

This definition is used in all contexts of science, engineering, business, and many areas of computing, including hard drive, solid state drive, and tape capacities, as well as data transmission speeds. However, the term is also used in some fields of computer science and information technology to denote 1073741824 (1024^3 or 2^30) bytes, particularly for sizes of RAM. The use of gigabyte may thus be ambiguous. Hard disk capacities as described and marketed by drive manufacturers using the standard metric definition of the gigabyte, but when a 500-GB drive's capacity is displayed by, for example, Microsoft Windows, it is reported as 465 GB, using a binary interpretation.

To address this ambiguity, the International System of Quantities standardizes the binary prefixes which denote a series of integer powers of 1024. With these prefixes, a memory module that is labeled as having the size 1GB has one gibibyte (1GiB) of storage capacity."

Do NOT assume that if you have X amount of bytes available (claim by any memory product), you can use that exact amount. Formatting will reduced it.

Not ALL storage products will give the same "maximum" amount. If the product is defective, formatting will "locked out" the bad area thus giving you less storage.

**Butters** · 6th September 2017, 12:38 AM

I absolutely agree with that excellent explanation osiris4isis, thanks for that. As well as the capacity variance between manufacturers, any individual drive which experiences bad blocks will have it's effective space reduced upon format because they will be 'locked out' as you've said. Additionally, even cards branded the same may vary a little in available space because some brands are 'fabless' manufacturers meaning they source batches of product from different factories.

Edit: The only truly non-confusing way for most ppl to converse about drive size is to use bytes. Inconveniently that means talking in 'rifle numbers'. If only MS would go the path of Mac and Linux and use the decimal factor for GB the mists would clear for many casual PC users.

**osiris4isis** · 6th September 2017, 01:18 AM

Yep, I once had a china made 4GB SDHC that was really only 1GB. Hardware wise it was made to look as if it was 4GB but as soon as you use more than 1GB, the data got corrupted. It turn out that they design the bank of memory chips to share a single 1GB capacity. So boys and girls, always go for name brand and check full capacity usage ASAP. Try to buy from dealers that you can return easily.
One more things about memory, all memory design have parity check and retry (or re-read) mechanism to make sure it can get at data. If there are some bits not "fully" working (gray bits) it will retry and that will slow down access time. This "effect" also occurred when near capacity is used. Experience user knows not to use full capacity. I stop around 90% full.

I agreed about using bytes instead of prefix shorthand for clarification, but it's like asking people to use actual term without using acronyms (painful)

Little out of topic, but I think it's important to know.

**Butters** · 6th September 2017, 02:15 AM

Continuing the interesting and important OT, I agree it's always wise to properly check the real capacity of any card particularly if from a source like ebay or ali. Like you I got an unbranded SDHC, purported to be 8GB but was only 2GB. I used H2testw and then sent the report and demanded a refund. The seller in China said to send it back, I said fine if you pay return postage or I'll open a dispute so he said ok keep it and refunded me. I recovered it with HDD LLF Low Level Format Tool as a 2GB card.

It's flaky as all getout tho' and really not usable.

Another limiting factor not widely known is the wear leveling built into flash memory. Slows down the older more used cards.

**jinxxxxxx** · 25th September 2017, 09:01 PM

Well I will let you guys stay with your limited 2gb CF cards I will continue to load my 4gb,8gb,16gb, 32gb cards with larger maps. When you find that you can't load all of the USA from the 2018.20 mapset I ques you will just have to use 2 2gb CF cards.

In reality it doesn't matter how much data a card can hold if it can't hold all the data you need it to hold it is of little use. And I do know what I'm talking about.

Now I only use Sandisk Class 10 for my maps if you guy are dumb enough to trust unbranded memory that says a lot about you.

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