HB-F1XV black screen

Page 5/5
1 | 2 | 3 | 4 |

By fallen1

Resident (43)

fallen1's picture

09-11-2019, 10:25

It's the secondary ROM without epoxy - IC bottom right next to the coin battery:

By fallen1

Resident (43)

fallen1's picture

14-11-2019, 23:53

Just by pressing F3 while booting, the MEGAFLASHROM boots to multiMente (which is distorted) - hitting ESC and ENTER puts me to DOS - from there I was able to flash a game rom and after the restart - IT WORKS!

Of course I've tried to flash the missing XV firmware ROM, but that kept the system stuck after the MEGAFLASHROM detects the SD card (same like when no ROM was flashed)

I have some more questions:
- What does the F3 key? Seems like it skips the default bios, but I found no trace of such boot option in the manual
- What can be the cause of the of the distorted MultiMente? I would guess the VRAM, but the game/boot logo/dos/basic (with 1M of RAM :evil: ) seem to be without any issues

Thanks

By fallen1

Resident (43)

fallen1's picture

15-11-2019, 23:32

Some other games have issues too, so it's going to be VRAM after all

By fallen1

Resident (43)

fallen1's picture

21-11-2019, 22:59

Replaced the VRAM (used Intel P21464-10) and now works great - beautiful stable screen and moreover works without the missing secondary ROM oO

By Pentarou

Master (226)

Pentarou's picture

21-11-2019, 23:39

Interesting, but were you getting the

Quote:

/boot logo/

even with the defective VRAM installed?

Quote:

What does the F3 key? Seems like it skips the default bios

I think it's a Nextor function:

2.9. Boot keys
The boot time configuration of Nextor can be modified by keeping pressed some special keys while the system
is booting. These keys and their behavior are:
[...]
3: Force boot to the BASIC prompt, ignoring any existing boot code (that is, do not try to load and run
NEXTOR.SYS, AUTOEXEC.BAS or the code in the boot sector).

By sdsnatcher73

Hero (652)

sdsnatcher73's picture

22-11-2019, 06:05

The 3 key is from Nextor indeed but that is numeric 3 and not F3. Also that would have gotten you into Basic not MultiMente. According to the MFR Manual the only thing F3 could be is to erase the ROM disk in the MFR, but not by holding it during boot but rather once you are in recovery mode. Maybe it was F5 which switches video to 50Hz (from 60Hz on a Japanese MSX) and might have allowed the VDP to work somehow with the faulty VRAM? Or F3 is an undocumented feature...

By fallen1

Resident (43)

fallen1's picture

22-11-2019, 11:23

Pentarou wrote:

Interesting, but were you getting the /boot logo/ even with the defective VRAM installed?

correct, that was very misleading. Not sure how the VRAM is used, but my guess is that the corruption was in the upper 64k chips. Therefore simple graphic games + boot logo animation were working fine and more complex were failing - e.g. MultiMente. Or as sdsnatcher73 has suggested - 50Hz video

sdsnatcher73 wrote:

The 3 key is from Nextor indeed but that is numeric 3 and not F3. Also that would have gotten you into Basic not MultiMente. According to the MFR Manual the only thing F3 could be is to erase the ROM disk in the MFR, but not by holding it during boot but rather once you are in recovery mode. Maybe it was F5 which switches video to 50Hz (from 60Hz on a Japanese MSX) and might have allowed the VDP to work somehow with the faulty VRAM? Or F3 is an undocumented feature...

It was F3 (tried all function-keys while waiting for the VRAM to arrive, so I was in no hurry Smile ) and couldn't find out what it does (to indicate which problem it's fixing for me).

Now it boots original cards too, so I'm happy (for now, will do 192kb VRAM + belt-less mod this weekend Running Naked in a Field of Flowers )

By fallen1

Resident (43)

fallen1's picture

27-11-2019, 23:35

Ok next problem. Wanted to load MegaReport to confirm VRAM upgrade using MegaFlashRom and flashing it using the DSK, but found out that there is a general problem with the FDD too.
Actually it's the reason why I have to press F3 while booting if there is no ROM cart loaded in the slots - accessing the FDD lights the floppy light on and then the system freezes. F3 or ROM cart in the slot skips the FDD access and then it boots fine.

Same thing happens when the FDD controller IC is out and/or FDD disconnected. Power connector around 5V and there is no motor activity. When I connect external drive, it's LED goes on just like the one on the device.

Measured following states using Logic Probe:

/REDWC (pin 2 ) not connected
n/c (pin 4 ) not connected
n/c (pin 6 ) not connected
/INDEX (pin 8 ) HIGH
/MOTEA (pin 10) LOW
/DRVSB (pin 12) 1V
/DRVSA (pin 14) not connected
/MOTEB (pin 16) HIGH
/DIR (pin 18) HIGH
/STEP (pin 20) HIGH
/WDATE (pin 22) HIGH
/WGATE (pin 24) HIGH
/TRK00 (pin 26) HIGH
/WPT (pin 28) HIGH
/RDATA (pin 30) HIGH
/SIDE1 (pin 32) HIGH
/DKRD (pin 34) HIGH

Tried to pull the pin 12 HIGH or LOW but no difference.
Any ideas what I could try next?

ps: Got the replacement Kanji ROM so now I can rule out missing ROM related issues

Page 5/5
1 | 2 | 3 | 4 |