if V9938/58 chip is faulty, does MSX ignore it and boot normally?

By bazabaza

Expert (70)

bazabaza's picture

05-08-2013, 11:06

I have an MSX that displays no signal from video out and black screen from RF . but it seems to boot normally to basic, if v9938/58 chip is the problem, could MSX boot?

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By Gradius2

Hero (569)

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05-08-2013, 19:04

All depends on BIOS.

If there is no routine there to verify if the VDP is fine or not, it would boot.

But probably there is such routine, so I guess is something bad after VDP, probably old caps (on video line) need to be replaced.

By NYYRIKKI

Enlighted (5176)

NYYRIKKI's picture

05-08-2013, 20:31

I think MSX will boot as long as the VDP interrupts are running fine... How ever I also think that it is unlikely that the VDP it self is the damaged part.

By bazabaza

Expert (70)

bazabaza's picture

06-08-2013, 03:01

Thanks for the helpful responses, I'll check then caps and the rest of the video circuit. hopefully something easy to figure out Smile . this one seems to work smoothly aside from video, compared to my other hb-f1xd

By PingPong

Prophet (3185)

PingPong's picture

06-08-2013, 20:40

bazabaza wrote:

Thanks for the helpful responses, I'll check then caps and the rest of the video circuit. hopefully something easy to figure out Smile . this one seems to work smoothly aside from video, compared to my other hb-f1xd

test to know if interrupts are ok: after boot press caps lock several times. if the caps lock led change status, ints are ok

By PingPong

Prophet (3185)

PingPong's picture

06-08-2013, 20:43

bazabaza wrote:

Thanks for the helpful responses, I'll check then caps and the rest of the video circuit. hopefully something easy to figure out Smile . this one seems to work smoothly aside from video, compared to my other hb-f1xd

test to know if interrupts are ok: after boot press caps lock several times. if the caps lock led change status, ints are ok

By bazabaza

Expert (70)

bazabaza's picture

06-08-2013, 20:56

it does work, I can type dir and the drive lights up, and even waits for "press any key". I press and it loads more files, but wasn't sure if MSX actually checks for response from VDP and if there is no responses locks up or not. seems it does then and the problem not from VDP? I guess.

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