MSX2 Philips VG-8235 - cable adapter for GOTEK DD

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By Briqunullus

Hero (584)

Briqunullus's picture

02-10-2022, 18:55

plxbollo wrote:

Maybe I'll leave it like it is and only use the externbal drive - does that have any downsides?

Not really. Maybe vulnerability. Recently my power cable broke (I've made a power connector on the back of the machine). Must be said that cable was at least 25 years old.

By plxbollo

Supporter (12)

plxbollo's picture

02-10-2022, 20:06

After connecting pin6 from c3 to pin 15 of the ext. hdd connector (which, so far I've read, is necessary to use both drives),
installing the bios and so on, I couldnt get the drives to work side by side, they showed themselves both as "A:",
and switching ther gotek to 1 didnt hep either. Anyway, as the internal FDD is making unpleasent noises, I disconnected it
to only use the GOTEK externally. Best way to got Smile

(first I thought, the external HDD connectoe is special, as I latzer realized that its only a usual floppy cable connector...)
Wink

By CASDuino

Champion (305)

CASDuino's picture

02-10-2022, 20:09

Don't forget that the 8235 can only read SD disks or 360k DSK files. If you want it to use double sided you need a new ROM and some wiring changes.

By plxbollo

Supporter (12)

plxbollo's picture

02-10-2022, 20:21

Already done that.

How may I alter the frequency (50/60) in the hex code of the BIOS?

By Briqunullus

Hero (584)

Briqunullus's picture

02-10-2022, 21:14

I have only done this once in openMSX, but it should work on real MSX as well. The SUBROM has default values for the VDP registers starting at address 0x29f6. You want to change register 9, that's 0x29ff. Change the value from 2 to 0.

Then there's an identification byte in the main ROM. Software can read that to discover machine properties. At address 0x002b reset bit 7. To do this, change the value from 0x91 to 0x11.

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