virtual start address: 0x00300000
syscall wrapper: 0x80020070
virtual RAM address: 0x08100000
Standardheader
| Offset (b) | Size (b) | Description |
| 0 | 8 | File identifier: “USBPower” |
| 8 | 1 | File type identifier |
| 9 | 5 | {0x00, 0x01, 0x00, 0x01, 0x00} |
| 0xE | 1 | Control byte: (LSB of filesize (at offset 0x13)) + 0x41 |
| 0xF | 1 | 0x01 |
| 0x10 | 4 | Total file size as unsigned integer, big endian format |
| 0x14 | 1 | Control byte: (LSB of filesize (at offset 0x13)) + 0xB8 |
| 0x15 | 1 | Unknown purpose (maybe 4-alignment), appears insignificant |
| 0x16 | 2 | this is suspected to be a CRC (doubtful!), but luckily it is not cared for by the fxCG20-OS |
| 0x18 | 8 | unknown |
| 0x20 | ... | Subheader depending on particular file type |
Known file types are:
0x2C Addin
Addin subheader
Addin subheader fields
| Offset (b) | Size (b) | Description |
| 0x20 | 4 | byte checksum: 0x00000000 to 0x0000001F and 0x00000024 to EOF minus 4 |
| 0x24 | 2 | 01 01 |
| 0x26 | 8 | unknown; obviously insignificant, usually 0x00 |
| 0x2E | 4 | filesize - 0x7000 - 4 |
| 0x32 | 14 | unknown; obviously insignificant, usually 0x00 |
| 0x40 | 16 | title |
| 0x50 | 12 | unknown; obviously insignificant, usually 0x00 |
| 0x5C | 4 | filesize |
| 0x60 | 8 | internal_name; preceded by @ |
| 0x68 | 3 | unknown; obviously insignificant, usually 0x00 |
| 0x6B | 24 | language_1_label; english |
| 0x83 | 24 | language_2_label; spanish |
| 0x9B | 24 | language_3_label; german |
| 0xB3 | 24 | language_4_label; |
| 0xCB | 24 | language_5_label; |
| 0xE3 | 24 | language_6_label; |
| 0xFB | 24 | language_7_label; |
| 0x113 | 24 | language_8_label; |
| 0x12B | 1 | 01 |
| 0x12C | 4 | 0 0 0 0 |
| 0x130 | 12 | version "01.00.0000",0,0 |
| 0x13C | 14 | stamp "2012.0903.1652 |
| 0x14A | 38 | all zeros |
| 0x170 | 36 | language_1_label; english |
| 36 | language_2_label; spanish | |
| 36 | language_3_label; german | |
| 36 | language_4_label; | |
| 36 | language_5_label; | |
| 36 | language_6_label; | |
| 36 | language_7_label; | |
| 36 | language_8_label; | |
| 0x0290 | 0xC2C | some 3C- or bw-bitmap |
| 0x0EBC | 0x144 | G3A filename; f. i. "PictPlot.g3a" |
| 0x1000 | 0x3000 | selected icon image |
| 0x4000 | 0x3000 | unselected icon image |
| 0x7000 | . . . | Addin code |
The CASIO SDK expects 30x19 bw BMP-files. The first and last line are omitted, when a G1A is assembled.
G3A-startup; fx-CG20; OS1.04
syscall sys0017 App_RegisterAddins_ validates add-ins, when the MAIN MENU is
built up.
1. the checksums at 0x20 and at the end of the file are compared (0x8002D376;
OS104).
2. the byte at 0x24 is checked to be 1 (0x8002D386; OS104).
The byte at 0x0E is not checked.
The byte at 0x14 is not checked.
With OS 1.04, the complete 0x10 bytes starting at 0x00 are not heeded for.
When the addin is started, the following checks
are done inside of 0x8002CB22 (OS104), called by syscall 0x0026 and 0x002C.
0x002C seems to check conv.g3a every time any addin is started.
At first the actual filesize is compared to the filesize stored at file-offset
0x5C (0x8002CB94; OS104).
Then it calculates and compares the checksum (0x8002CCBE; OS104).
Two address-ranges 0xFE240000 and 0xFE241000 are involved in addin-loading. They contain at least 63 int-values, which are initialized with zeros. If an addin is considered to be OK the correspondig entry in table 0xFE240000 is 1. If a checksum-mismatch or a filesize-mismatch is detected, the corressponding value in table 0xFE240000 will be 2. These memory-ranges are a bit peculiar. The calculator freezes, if INSIGHT tries to display the memory-ranges. Theses addresses obviously are not used in the GII-2 series' OSes.
(18.05.2012 17:16:07)