Beginner with SVI-738 please help

Supporter (6)

13-07-2012, 22:51

I got a defective SVI-738 as part of a lot. At first it didn't boot at all (black screen). Now after an year I decided to try and fix this thing and opened it. I found some kind of jumper wires on the bottom side of the mainboard and noticed that one of them was shorted on some pin. After sorting out the short circuit I got the thing to boot!

As I didn't get any disks with it I tried to make a disk to test it from 738msxdos.dsk downloaded from bluemsx.com. I used Disk-Manager to save the DSK-image to disk (360k). I didn't get the thing to load. Anyone knows where is the problem? I have no idea how to use a MSX but tried to google some commands that might work but I really have no clue what to do. The problem could be the user (me), MSX, disk drive or the disk. Who knows?

Here's my output:

Disk BASIC version 1.0
Ok
load"autoexec.bas",R
Direct Statement in file
Ok
files
MSXDOS.SYS COMMAND.COM
CHANGE.COM WIDTH.COM
...
[bunch of files here...]
...
IS.BAS
Ok

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Van mars2000you

Enlighted (6499)

13-07-2012, 23:22

The original disk rom of the SVI-738 is known to be very temperamental, that's why Henrik Gilvad has created a better disk rom for this machine (check the Resource page of the blueMSX website). Maybe the problem is there. You can check the problem by trying different 360 kb DSK images in the different versions of the SVI-738 supported by blueMSX.

Van Manuel

Ascended (19469)

14-07-2012, 08:27

Tomi, let's first try this:

1) get a (new) blank disk
2) put it in a booted 738 (it is in BASIC)
3) in BASIC, type: CALL FORMAT
4) when it is done try to save a file to it like this:

10 PRINT "TESTING..."
20 GOTO 10

SAVE"TESTING.BAS"

then reset the MSX and type: RUN"TESTING.BAS"

If this all works without errors, your drive seems to work, at least.

Van Tomi

Supporter (6)

14-07-2012, 09:00

mars2000you wrote:

Thanks for replying!

Ok, I upgraded the disk rom and now it says this on the startup:

Disk BASIC version 1.3
Ok

So it seems everything went fine. I also created a new disk to test but still it gives me:
load"autoexec.bas",R
Direct statement in file
Ok

What does this mean? What is the most basic thing you can do to test if the disk drive works? I mean it does print the directory with command "files" but I can't get anything to load. The problem is also that I'm quite unsure what are the correct commands to load anything.

I've tried:
load"autoexec.bas",R
Direct statement in file
Ok

run"autoexec.bas"
Direct statement in file
Ok

bload"demo.com"
Bad file mode
Ok

bload"demo.com",R
Bad file mode
Ok

load"readme.bas",R
Direct statement in file
Ok

So could you give me a hint what I'm supposed to type that should work? As I told already, this is my first touch with any MSX computer so I don't know any of the commands to use.

Van Tomi

Supporter (6)

14-07-2012, 09:10

Manuel wrote:

Tomi, let's first try this:

1) get a (new) blank disk
2) put it in a booted 738 (it is in BASIC)
3) in BASIC, type: CALL FORMAT
4) when it is done try to save a file to it like this:

10 PRINT "TESTING..."
20 GOTO 10

SAVE"TESTING.BAS"

then reset the MSX and type: RUN"TESTING.BAS"

If this all works without errors, your drive seems to work, at least.

Thanks!

So I type the program and saved to disk and it seems to work allright:

call format
Drive name? (A,B) a

HG´s QuickFormat
1) 80T 1S
2) 80T 2S
3) 40T 2S
? 1
Strike a key when ready
Format complete
Ok
10 print "testing..."
20 goto 10

list
10 PRINT "testing..."
20 GOTO 10
Ok
save"testing.BAS"
Ok

[reset]

run"testing.BAS"
testing...
testing...
testing...
testing...
testing...
testing...
Break in 10
Ok

So the disk drive works, right?

Van Tomi

Supporter (6)

14-07-2012, 09:29

Solved!

It was my PC's disk drive that was messing thing up. I tried to write the disk with my old Windows98 laptop and now it works. Never trust computers manufactured after 2k.

Now I have to learn what "Schijf copiëren ? (J/N)" means...

Van Manuel

Ascended (19469)

14-07-2012, 11:04

It means "Copy disk? (Y/N)". Which program says that? It's Dutch...

Anyway, I don't think you really had to replace the diskROM, but OK. I guess it won't hurt as HG's stuff is usually good.

Van RetroTechie

Paragon (1563)

14-07-2012, 16:20

The biggest problem is the MSX 360K format. PC's also know a 360K format, but that's 40 tracks, double sided (5,25"). The 80 tracks, single sided 360K format as used on MSX, is simply unknown/unsupported by PC's and BIOS software etc refuses to write to that properly.

The obvious fix is to go around that, use a custom app that knows these formats and does low level sector I/O. But that only works on an OS where you can do low level sector I/O. Not difficult for DOS & Win9x, hard/impossible on Win2k and up.

The other option is to replace that SVI-738's drive with a 720K one. Don't know how difficult that is, but if possible that would make a lot of floppy I/O issues easier. Optimal is to bypass floppies altogether and go CF/SD card route.

Van Tomi

Supporter (6)

14-07-2012, 17:09

Thanks for information, RetroTechie. I think I'll try to change the disk drive to 720kb disk drive. I wonder if this new ROM supports 720kb already? Is there anything else I need to change to make the 720kd disk drive to work?

I already fixed the "N" and "M" issue by desoldering the crappy plastic ribbon cable and replaced it with regular ribbon cable with connector on the mainboard. Much easier to open and do upgrades now.

I wonder what for these weird three cables running across the mainboard on the solder side? I think the another mod made here is a RGB connector. I can't imagine it's anything else. I'll try to take photos today if you could tell me what you think.

Van Tomi

Supporter (6)

14-07-2012, 20:51

I took some pictures of some things I wondered of.

So this is the hack I wondered what it is: