DRVIO board
This board implements a shugart bus interface as used in the standard PC floppy disk drives (5.25" and 3.5") in a way that is compatible with the Commodore VC1581 disk drive. I.e. it is planned that this board, together with the PETCPU board, make up a VC1581 replacement.
To accomodate this, the ICs can be addressed either via the bus I/O area, or via a mapping into the 1Mbyte bus memory address space - so it can mimick the 1581 address space.
Additionally, the board contains a Commodore IEC bus interface, as well as an infrared signal generator.
Table of content
PETCPU test
This file includes a small test program that does a "readaddress" command on the WDC and either prints the sector header (in reverse) or the WDC status register in case of an error.
This driver runs on a PETCPU with the Commodore PET ROMs (just 'dL"test1"' :-) and expects the card I/O at $E8A0 (WD177x) and $E8B0 (CIA).
Version: 1.1A
Status: ok
Notes
These are the differences:
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This version is (slightly) incompatible with the previous one due to changes in the SEL and MTR lines. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
This board implements a (shugart-type i.e PC-type) floppy disk controller. The board has been tested with 3.5" PC disk drives with DD (double density disks) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Using this board with HD-drives (i.e. 1.44M 3.5" floppies overclocks the WDC1772 chip used in this board, as it is only specified for DD-disks (720k). | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Here is a summary of the jumper settings:
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Files
csa_drvio_v1.1a.sch | |
csa_drvio_v1.1a-sch.png | |
csa_drvio_v1.1a.brd | |
csa_drvio_v1.1a-brd.png | |
petcpudrv.jpg(Picture of setup with PETCPU system. Boards from left to right: DRVIO, PETCPU, PETIO, VDC) | |
vc1581drv.jpg(Picture of setup as VC1581 together with PETCPU board.) |
Version: 1.0B
Status: prototype
Notes
The layout has not been tested, only the schematics
has been implemented by modifying my Rev.A board
to Rev.B. The differences are:
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This board implements a (shugart-type i.e PC-type) floppy disk controller. The board has been tested with 3.5" PC disk drives with DD (double density disks) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Using this board with HD-drives (i.e. 1.44M 3.5" floppies overclocks the WDC1772 chip used in this board, as it is only specified for DD-disks (720k). | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Here is a summary of the jumper settings:
|
Files
csa_drvio_v1.0b.sch | |
csa_drvio_v1.0b-sch.png | |
csa_drvio_v1.0b.brd | |
csa_drvio_v1.0b-brd.png | |
petcpudrv.jpg(Picture of setup with PETCPU system. Boards from left to right: DRVIO, PETCPU, PETIO, VDC) | |
petcpujump.jpg(Jumper settings for PETCPU setting) | |
vc1581drv.jpg(Picture of setup as VC1581 together with PETCPU board.) |
Version: 1.0A
Status: prototype with bugs
Notes
This board is superseded by the 1.0B version and will not be supported by any drivers. | |
The drive select signals are driven the wrong way round. I.e. in a VC1581 setup after reset, the wrong drive is selected and the drive would not work. | |
This board implements a (shugart-type i.e PC-type) floppy disk controller. The board has been tested with 3.5" PC disk drives with DD (double density disks) | |
Using this board with HD-drives (i.e. 1.44M 3.5" floppies overclocks the WDC1772 chip used in this board, as it is only specified for DD-disks (720k). | |
I found that modern 3.5" disk drives do not drive the DENSEL shugart bus signal (and not need it either). Thus the selection of HD/DD disks will change from shugart bus drive to I/O port driven. | |
The Infrared signal generation will be changed to a NE555 based solution. Signal polarity may change, as it is currently enabled after reset. | |
The board lacks a feature to drive the ATN line - so it cannot be used as a IEC bus master. This feature will be added if possible. |