Canon V-30F MSX2

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By mars2000you

Enlighted (6229)

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05-11-2021, 23:50

Manuel wrote:

I tried to make an initial openMSX config for the machine. But the problem is the disk circuit. Can someone reverse engineer the disk ROM to find out how it expects the FDC to be connected to the MSX? Looks like none of the existing connection styles implemented in openMSX are compatible with it. (I either get a hang-up, no Disk BASIC or Disk I/O errors.)

I've already mentioned this very complete page in the past: http://www.ascat.jp/tg/tgd5.html

CANON part (Google translation) :

     8 CANON

● Type name and applicable model
  Type name Manufacturer Model name Slot
 CANON 1 CA1 CANON V-30F 3-1

● Various data
  FDC Work area length Format work area length
 8876 series 7 bytes Not used

 Corresponding media F8H to FBH 1: F8H 2: F9H

● driver within the subroutine address
    DSKIO DSKCHG GETDPB CHOICE DSKFMT MTROFF OEMSTA INIHRD DRIVES INIENV
 CA1 744DH 77ABH 7816H 7842H 7BC1H 7748H 782DH 7728H 776BH 77A0H

● disk driver job offer number
    MYSIZE SECLEN DEFDPB
 CA1 0007H 0200H 7416H

● I / O port
 7FF0H R status Register
    W Command register
 7FF1H R / W Track register
 7FF2H R / W Sector register
 7FF3H R / W Data register
 7FF4H R / W / / / / / / / MOT / SIDE /
 7FF5H R / W
 7FF6H R / W
 7FF7H R FDC Status / -DRQ / IRQ /-/-/-/-/-/-/

  MOT 1 with motor ON
  SIDE side select signal-
  DRQ FDC DRQ signal inversion
  IRQ FDC IRQ signal

By Manuel

Ascended (18788)

Manuel's picture

06-11-2021, 00:36

Hmm, it doesn't seem to specify how drive select works... Also, after implementing it like this, it still hangs up.
(It seems similar to the Toshiba one by the way... just lacking disk change signal and drive select for some reason.)

By mars2000you

Enlighted (6229)

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06-11-2021, 00:45

Another difference is in the format used by the work area: 7 bytes instead of 10 bytes.

By Manuel

Ascended (18788)

Manuel's picture

06-11-2021, 09:41

Is there a picture of the FDC chip?

By Manuel

Ascended (18788)

Manuel's picture

06-11-2021, 09:45

mars2000you wrote:

Another difference is in the format used by the work area: 7 bytes instead of 10 bytes.

Well, not sure what he means there. It does seem to be a special kind of FDC, which may not be WD2793 compatible.

By mars2000you

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06-11-2021, 10:14

Manuel wrote:

Is there a picture of the FDC chip?

You can see a MB8877A chip on the lower PCB.

By gdx

Enlighted (5503)

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06-11-2021, 10:35

Maybe this is a bit clearer:

Type name and corresponding model:
Type name = CANON 1
Manufacturer = CA1 CANON
Model name = V-30F
Slot = 3-1

Various data:
FDC = 8876 series
Work area length = 7 bytes
Format work area length = Not used
Corresponding media: F8H~FBH (1 for F8H, 2 for F9H)

Subroutine addresses in the driver CA1:
DSKIO = 744Dh (4010h)
DSKCHG = 77ABh (4013h)
GETDPB = 7816h (4016h)
CHOICE = 7842h (4019h)
DSKFMT = 7BC1h (401Ch)
DSKSTP = 4877h (401Fh)
STBAS = 5B3Ah (4022h)
FORMTM = 60B1h (4025h)
FORMTK = 60B1h (4026h)
MTOFF = 620Dh (4029h)
GTSLT1 = 5FB3h (0402Dh)

OEMSTA = 782Dh
INIHRD = 7728h
DRIVES = 776Bh
INIENV = 77A0h

Constants in the disk driver CA1:
MYSIZE = 0007H
SECLEN = 0200H
DEFDPB = 7416H

I/O port:
7FF0H = R - Status register / W - Command register
7FF1H = R/W - Track register
7FF2H = R/W - Sector register
7FF3H = R/W - Data register
7FF4H = R/W - [-|-|-|-|-|-|MOT|SIDE] (Set MOT to Motor ON, SIDE is side select signal)
7FF5H = R/W - 
7FF6H = R/W - 
7FF7H = R - FDC Status [/DRQ|IRQ|-|-|-|-|-|-] (/DRQ and IRQ bits indicate corresponding signal states from the FDC, /DRQ is an inverted signal)

I don't know where CANON 1 and CA1 come from.

mars2000you wrote:

I've already mentioned this very complete page in the past: http://www.ascat.jp/tg/tgd5.html

This site have nice information but it's not indicated when given information are standard or not.

By mars2000you

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06-11-2021, 10:57

mars2000you wrote:
Manuel wrote:

Is there a picture of the FDC chip?

You can see a MB8877A chip on the lower PCB.

There is also a MB62H168 chip on the drive PCB .... A CMOS Gate Array: https://www.cryptomuseum.com/crypto/philips/px2000/files/MB6...

Maybe a special connection between both chips???

By msxholder

Champion (399)

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06-11-2021, 20:32

The machine gave me an surprise When i pull out the drive there is no disk basic anymore.
The other two 40 pin chips are in this machine Toshiba TC170005AP-0007.
Not the MB62H168.
The register of the Mapper is 4 bits so it can be expanded to 256 kB ?
There are also locations for another 64 kB.

By Manuel

Ascended (18788)

Manuel's picture

06-11-2021, 20:29

I asked Wouter to help and he took a look at that disk ROM dump. It seems it works totally different than this document describes. More details later when everything is sorted out.
Of course it is possible the drive of this prototype is connected in a (totally) different way than the final version, but it doesn't seem too likely. But we could confirm if we also get a ROM dump of the released/final V-30F.

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