National FS-VG501, repair and usage problems

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By popolon_

Master (153)

Аватар пользователя popolon_

12-03-2021, 12:40

I have National FS-VG501 that is not working. First there was power switch broken, and now when power is on, there is distorded image:
P_20210311_223813_vHDR_Auto.jpg

The distorded picture appears only when module is inserted in msx. No picture is get from this unit when module is not inserted to msx. So at least somehow module is doing something to activate this unit? I used now Toshiba HX34, but could also try with panasonic a1wx/a1st/a1gt.
If i press and hold the input selector, then picture from computer appears same way distorded:
P_20210311_223824_vHDR_Auto.jpg

There seems to be at least 512KB memory in this unit.
P_20210311_194154_vHDR_Auto.jpg

In module side, there is eprom and some logic chips.
P_20210312_131811_vHDR_Auto.jpg

So would the problem be ram? Or module corrupted eprom? Or something else?

And where is the softaware and usage instuctions for this as wiki page does not say anything? Same softaware as for National FS 5500?

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By mars2000you

Enlighted (5833)

Аватар пользователя mars2000you

12-03-2021, 13:05

I think that the software provided with the FS-5500 can be used.

Check also these MSX-BASIC instructions:

https://www.msx.org/wiki/SET_VIDEO

https://www.msx.org/wiki/COPY_SCREEN

There is a BIOS rom in the cartridge, it would be interesting to dump it, maybe it contains a specific MSX-BASIC extension with new instructions.

By popolon_

Master (153)

Аватар пользователя popolon_

12-03-2021, 13:54

Yes, those two commands give "Ok" output. I tried to run that example code in copy screen wiki page, but picture stays just white.
But shuold the computer screen be visible as default output?
The current default output (from composite output connector, i have no cable yet for that rgb connector) can be seen in this short video:
https://github.com/popolonx/MSX_STUFF/blob/main/FS-VG501/V_2...

By popolon_

Master (153)

Аватар пользователя popolon_

12-03-2021, 14:21

I dumped the rom, it can be found from:
https://github.com/popolonx/MSX_STUFF/blob/main/FS-VG501/FS_...

By mars2000you

Enlighted (5833)

Аватар пользователя mars2000you

12-03-2021, 16:08

You need probably this floppy disk to use the National FS-VG501: https://aucview.aucfan.com/yahoo/p836027464/

By popolon_

Master (153)

Аватар пользователя popolon_

12-03-2021, 16:22

yes, I bought that disk, but that is empty or faulty disk (disk I/O error when giving FILES command, in toshiba HX34 and in Philips NMS8245). I do not know if that disk could be read via KryoFlux (I have that). anyway I have that FS5500F1 + the original disk with Video Graphics.

By popolon_

Master (153)

Аватар пользователя popolon_

12-03-2021, 20:13

The disk was clearly empty non-formated disk, as kryoflux said:
...
83.0 : frev: 21222, drift: 0.520 us, tfer: 124547 B/s, rpm: 300.513
83.0 : base: 0.884 us [53.217%], band: invalid
83.0 : MFM: unformatted
83.1 : frev: 7292, drift: 0.042 us, tfer: 57165 B/s, rpm: 300.523
83.1 : base: 1.042 us [29.104%], band: 3.127 us
83.1 : MFM: unformatted
and resulted file was 0 bytes.
So this disk was not as advertised.

By popolon_

Master (153)

Аватар пользователя popolon_

12-03-2021, 21:20

The disk was sold by same seller as the whole unit. But how can the disk be totally unformatted? Disk would go that bad over 35 years?

By mars2000you

Enlighted (5833)

Аватар пользователя mars2000you

12-03-2021, 21:24

Maybe kept in a very bad situation.

By popolon_

Master (153)

Аватар пользователя popolon_

12-03-2021, 21:30

Is the rom dump valid or corrupted?

By popolon_

Master (153)

Аватар пользователя popolon_

13-03-2021, 10:02

There is fpga and asic chips in this unit. One SLA6170C and one SLA6430F. Four Toshiba TC15G008AP-036 gate arrays. So if any of those are broken, game over...
And total memory is
16x4464-15 =512KB
4x4464-15 = 128KB
4x4164-15 = 32KB

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