DVB-T Set top box with MSD7818?

[BonePit685]

I found an old set top box with what i assume is the MSD 7818. I got into U-boot (output attached below).
The firmware files can be downloaded from here, mine is the WIWA HD-80 evo:
https://www.gutek.com.pl/softy.htm

BOOTSPILMLMLMLM7696_OK!decomp
_done

Hello U-Boot


U-Boot 1.1.6 (Dec 21 2015 - 11:19:34)

Board: MSTAR KAPPA (CPU Speed 600 MHz)
DRAM:  64 X 0 MBytes
U-Boot is running at DRAM 0x87610000
Module: USB FAT FLASH SPI LOGO OSD ENV=SERIAL 
Flash is detected (0x0C02, 0xC8, 0x40, 0x16)
In:    serial
Out:   serial
Err:   serial
MSVC00B000100100208768TH0000000T
[MDrv_PNL_Init][524] 
MDrv_PNL_Init u32PnlRiuBaseAddr = BF200000
[MDrv_PNL_Init][535] 
MDrv_PNL_Init u32PMRiuBaseAddr = BF000000
[MDrv_PNL_Init][545] 
[MApi_PNL_Init][1118]
[_SetPanelParams][469] 
[MDrv_PNL_SetPanelType][553] 
[MDrv_PNL_SetPanelType][575] 
[_MDrv_PNL_Init_LPLL][295]pstPanelInitData->u16Width=1920, pstPanelInitData->u16Height=1080
[_MDrv_PNL_Init_LPLL][297]u16HTotal=2640,u16VTotal=1125,pstPanelInitData->u16HTotal=2640,pstPanelInitData->u16VTotal=1125, u16DefaultVFreq=500
[_MDrv_PNL_Init_Output_Dclk][340]pstPanelInitData->u16Width=1920, pstPanelInitData->u16Height=1080
[_MDrv_PNL_Init_Output_Dclk][342]u16HTotal=2640,u16VTotal=1125,pstPanelInitData->u16HTotal=2640,pstPanelInitData->u16VTotal=1125, u16DefaultVFreq=500
[XC,Version] 00442327
 UTOPIA ASSERT: 0 /home/stb/PERFORCE/THEALE/utopia/project/kappa_nos_mips_mboot/../../mxlib/hal/kappa/xc/mhal_sc.c Hal_SC_set_ficlk 224
DAC eTiming =8
HDMITx eTiming =12
HDMITx eTiming =12
[Hal_VE_EnableDI][1049] bEnable = 0, bIsDNR2VE = 0
u32ReadBuffVirAddr = A0000000, u32IntBuffVirAddr = A0100000, u32OutBuffVirAddr = A0730000
verJPD_SetStatus >>>>>>>>>>> w:720,  h:576,  p:720

[GOP3, PID 0][Driver Version]: 0089, BuildNum: 0002, ChangeList: 00524916
 keypad_pressed is [0] 
 ir_pressed is [0] 
Hit any key to stop autoboot:  0 

<< MStar >># printenv
bootdelay=0
baudrate=115200
preboot=echo;echo Type "help" for more commands.
MS_BOARD=BD_MST173A_D01A
logo_cmd=boot_logo 0 0 1 1
info_exchange=spi
AP_SW_VERSION=0x0001
HW_MODEL=0x0001
HW_VERSION=0x0001
skip_standby=0
OAD_NEED_SCAN=0
USBUpdateFlag=0
usb_upgrade_port=0
partno=1
usb_upgrade_path=usb_upgrade_all_flash.bin
filesize=3002F8
usb_upgrade=0
bootcmd=spi_rdc 0x80b00000 0x7001c 0x28f2d8; LzmaDec 0x80b00000 0x28f2d8 0x80000180 0x81000000; go 0x80000224;
usb_complete=0
OAD_IN_MBOOT=1
CUSTOMER_OUI=0x4C5427
AP_SW_MODEL=0x0012
panel_cmd=set_paneltype 17
OAD_NEED_UPGRADE=1
OAD_FREQ=479000
OAD_BAND=8
OAD_PID=1260
oad_complete=0
OAD_TRIGGER_TYPE=0
AP_OSD_LANG=1
TIMER_AFTER_OAD=758001603
stdin=serial
stdout=serial
stderr=serial

Environment size: 733/65532 bytes
<< MStar >># 

Photos of the device:

I read the "adding a new chip", however it seems to crash the device:

<< MStar >># md.w 0x1f003c00
1F003C00:
Exception: 10
RI: Instruction code not recognized (or not legal)
  $zero: 00000000  $at: 00000000  $v0: 00000002  $v1: 00000080
  $a0: 00000004  $a1: BF200000  $a2: 00000001  $a3: 00000000
  $t0: 00000003  $t1: 00000001  $t2: 00000003  $t3: 00000002
  $t4: 00000020  $t5: 876AF188  $t6: BF2033D4  $t7: BF203398
  $s0: 00000002  $s1: 00000002  $s2: 877791D8  $s3: 1F003C00
  $s4: 00000010  $s5: 877791D8  $s6: 877791D8  $s7: 8762AFC4
  $t8: 876FE7A0  $t9: 87634CBC  $k0: 74796220  $k1: 000A7365
  $gp: 876D8960  $sp: 877791C8  $fp: 877791D8  $ra: 8761BE34
   sr: 34008C02   pc: 8761BE9C  cause : 10000028  badvr : 000000C0

stack backtrace
stack frame #0: ra = 8761BE34, sp = 877791C8
stack frame #1: ra = 87612074, sp = 87779218

I do not have much knowledge about these kinds of things.
Where do i go on from here? Please tell me what I can provide.

[Error1429]

It's possible to run Linux on these set top boxes. See this: #73

[BonePit685]

Thanks for the info! I'll try that when I have some time and report back

[Error1429]

Have fun!

[FUS132]

Kappa is "MSD7802", according to the list of MIPS on Linux-Chenxing, 600mhz cpu speed lines up at least.
I have a "World Vision T34i" tv box from UA-RU region myself which is almost identical to this one, and it's specs page has that CPU listed also. Haven't got around to soldering the uart pins onto it for dumping yet though.

Link to firmware/specs of said TV box: https://www-world--vision-ru.translate.goog/products/efirnye-priemniki/world-vision-t34i?_x_tr_sl=ru&_x_tr_tl=en&_x_tr_hl=en-US&_x_tr_pto=wapp