ok .... after building up new collection of MSX Computers (well, three until today) I got some question regarding my Philips VG-8235 !

It has an internal 360KB Disk Drive but the belt is defective, so it´s not really usefull right now .... So I decided to use one of my external drives which came with my HitBit 75D as second drive on the 8235 ! It´s allready a PC drive, on the MSX1 Controller it works as 360KB but as external drive on my 8235 I can use 720KB on it

- So, is it normal that the external drive on 8235 can be a double sided one ?
- Can I use the external drive as internal one for booting etc. without modifying the hardware ? I don´t want to assemble inside the case so removing the 360KB original drive is out of question !!!!!

I've heard different stories about it. But to use it as an a-drive, you need to disconnect the internal drive anyway, and then the external drive should be set to DS0, iirc. But I don't know whether the 8235 will treat it as a double-sided drive then.

If you want a 720K FDD internal in the VG8235, you need to change the diskrom.
I don't know how to do that, but I'm sure somebody here can help you.

K.

Quote:

If you want a 720K FDD internal in the VG8235, you need to change the diskrom. I don't know how to do that, but I'm sure somebody here can help you. K.

I know that, but as I said, I don´t want to rip out the 360KB DiskDrive

It all depends on whether the external drive has its own diskrom or no. If it's connected through the cartridge port, it has. If it is connected to the 'external FDD' connector, I don't know. In the latter case, I doubt it has, honestly. For if it has a DiskROM it would need data and address lines to be able to access and run it, which would make the slot virtually the same as a cartridge slot. If it is merely an external connector for the diskdrive (which seems much more likely to me), it does not have its own DiskROM, and thus the computer would need a new one for a DS drive as the original DiskROM can only handle SS drives.

However, replacing the DiskROM may be quite a simple matter if it is fitted in a socket; you wouldn't need to solder then.


~Grauw

Ok, I´ll try again

1.) if I connect the external drive WITH FD-Controller to ANY MSX -> 360KB
2.) if I connect the external drive to the external port of 8235 -> 720KB as drive b

So, that means, the 8235 MUST be able to use DS drives .... all I want to try, is use the external drive as drive a with 720KB without changing diskrom or put it inside as internal drive

Any suggestions ???

Hm-hm, the 8235's disk controller can handle 720kb alright... It's just that its BIOS (DiskROM) can't. When replacing the internal drive with a DS one, it doesn't support it with the default DiskROM, you need to replace it. So I highly doubt that that DiskROM *would* support external drives of larger capacity (well, only in SS mode, I'd say)...

Since you say it works, my guess is that the internal DiskROM has already been replaced with one supporting DS? Although that wouldn't make sense as there is still an SS drive inside... Hm... Maybe someone else can shine some light on this? Maybe it supports 720kB only on the external connector? But that would be strange, and would an 8245's DiskROM then make it loose support for drives connected to it? Gah, confusing, this.

Anyways, if you want the drive as your A: drive, you must connect it through the cartridge slot and let the DiskROM be detected before the internal one. This because the order drives letters are assigned is determined during boot-time, when detecting and initializing the DiskROM's (well, if I'm not mistaking ). As the internal one is in (internal) slot 3, this should be no problem . However, your problem is, I think, that the drive does support 720kB, but your FDD-controller cartridge doesn't support it. Again, I think, a matter of replacing the BIOS (but now in the FDD-controller), but I'm not sure.

The external slot of your 8235 is hardwired to be assigned as B: drive, and it would at least involve some modification of the internal drive (setting it to accept DS1 instead of DS0) to change that.

In any case, what's against modding your MSX a little?


~Grauw

Quote:

Hm-hm, the 8235's disk controller can handle 720kb alright... It's just that its BIOS (DiskROM) can't. When replacing the internal drive with a DS one, it doesn't support it with the default DiskROM, you need to replace it. So I highly doubt that that DiskROM *would* support external drives of larger capacity (well, only in SS mode, I'd say)... ~Grauw

This is not entirely true: a 8235 will use a 720 kB drive when connected to the extrenal connector. It's DiskROM can cope with 720 kB disks and can format them as 720kB but my guess is this only works on the external connector because the diskROM is programmed to treat (any) a-drive as a 360 kB one...