# Confused about memory size for customised apps
**URL:** https://forum.sierrawireless.com/t/confused-about-memory-size-for-customised-apps/1964
**Category:** Open AT
**Created:** [March 4, 2008, 10:08pm UTC](https://forum.sierrawireless.com/t/confused-about-memory-size-for-customised-apps/1964 "2008-03-04T22:08:33Z")
**Posts on this page:** 6
**Page:** 1
### Author:  [@cgaolei](https://forum.sierrawireless.com/u/cgaolei)
#### Post date: [March 4, 2008, 10:08pm UTC](https://forum.sierrawireless.com/t/confused-about-memory-size-for-customised-apps/1964/1 "2008-03-04T22:08:33Z")
Hi, I am new to Open AT and wavecom products. Currently, I am evaluating the Q24Plus modem for embedded product of my company. However, I got confused about the memory size that our application can use:
From the product specification document I know that the Q24Plus has 32Mbits(4 Mbytes) Flash Memory and 16Mbits(2 Mbytes) RAM. (as I am a software developer, I prefer to talk about storage unit in bytes). So, I assume that the application can control all 4Mbytes flash and 2Mbytes of RAM.
But from an other document - ADL User Guide for Open AT OS v3.13 (WM\_ASW\_OAT\_UGD\_00006-011) Page 17:
> [@](#):
>
> For products with 32-Mbit flash size and 16Mbit RAM size:
> 768 Kbytes of ROM (application code)
> (configurable; see AT+WOPEN command)
> 1664 Kbytes of RAM
> 128 Kbytes of Flash Object Data
> 768 Kbytes of Application & Data Storage Volume
> (configurable; see AT+WOPEN command)
>
> The total available flash space for both Open AT® application place and A&D storage
> place is 1536 Kbytes. This space is shared between the two places.
>
> The maximum A&D storage place size is 1280 Kbytes (1.2 Mbytes: usable for
> Wavecom Core Software upgrade capability); the Open AT®application maximum
> size, in this case, will be 256 Kbytes.
>
> The minimum A&D storage place size is 0 Kbytes (usable for applications with huge
> hard coded data); the Open AT® application maximum size will, in this case, be 1.5
> Mbytes.
Just confused about those different numbers:
What is the actual RAM size for Q24plus that our program can control of? 1.6Mbytes OR 2Mbytes?
What is the actual Flash Memory size for Q24plus for data storage? 4Mbytes or 1.5Mbytes or 768Kbytes?
Thanks
---
### Author:  [@awneil](https://forum.sierrawireless.com/u/awneil)
#### Post date: [March 5, 2008, 6:36am UTC](https://forum.sierrawireless.com/t/confused-about-memory-size-for-customised-apps/1964/2 "2008-03-05T06:36:53Z")
> [@cgaolei](#):
>
> So, I assume that the application can control all 4Mbytes flash and 2Mbytes of RAM.
WHy do you assume that?
These are the chip sizes - remember that they also have to accomodate the GSM Stack and the Open-AT operating system…
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### Author:  [@cgaolei](https://forum.sierrawireless.com/u/cgaolei)
#### Post date: [March 5, 2008, 8:22pm UTC](https://forum.sierrawireless.com/t/confused-about-memory-size-for-customised-apps/1964/3 "2008-03-05T20:22:04Z")
Thanks for your reply. I just want to confirm the memory size, because the document does confuse me when reading it first time. 😃😃
So, for Q24Plus, the application can use 1.6Mbyte RAM and up to 1.2Mbyte of flash memory. Right? correct me if i am wrong.
---
### Author:  [@trthaithong](https://forum.sierrawireless.com/u/trthaithong)
#### Post date: [April 1, 2008, 8:06am UTC](https://forum.sierrawireless.com/t/confused-about-memory-size-for-customised-apps/1964/4 "2008-04-01T08:06:08Z")
Hi cgaolei,
With Q24PL:
RAM is 1.6MB and used for: Stack Size (Call Stack), Heap Size (Heap memory), and GlobalSize (Global variables)
Flash is 128KB (30KB is maximum for one ID, and maximum is 2000 ID exist at the same time)
A&D storage is 1.6MB, using for storing the application embedded or data. You can use this area as flash, the maximum to config this area for flash is 1.2MB (you can use AT+WOPEN=6,… to config this area), it is depend on your appl size.
BR,
ttt
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### Author:  [@djurodrljaca](https://forum.sierrawireless.com/u/djurodrljaca)
#### Post date: [August 29, 2008, 10:30am UTC](https://forum.sierrawireless.com/t/confused-about-memory-size-for-customised-apps/1964/5 "2008-08-29T10:30:42Z")
So how much memory do you have for your custom functions/tasks? Is it 128kB or is it a part of the “A&D storage” (is one part for the functions/task and another part for data storage)?
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### Author:  [@trthaithong](https://forum.sierrawireless.com/u/trthaithong)
#### Post date: [September 3, 2008, 2:37am UTC](https://forum.sierrawireless.com/t/confused-about-memory-size-for-customised-apps/1964/6 "2008-09-03T02:37:48Z")
Hi,
Clearly that with Q24Pl you can use 128KB flash and a part of A&D storage that maximum up to 1.2MB.
ttt