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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.

  •  
    2006-11-26 Published the board
 

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:
  • The infrared sender is removed
  • Fix pull-ups in the floppy interface
  • Add databus driver and own 16MHz oscillator
  • Re-org the control port, fix polarity of MTR and SEL signals, so all drives are off on reset
  • New layout
 
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:
JumperDescriptionSettingMeaningVC1581 settingstandard setting
JP1I/O address selection1-2$E8A*/$E8B*don't care*
2-3$E8E*/$E8F*
JP216MHz source1-2Take 16MHz from Bus
2-3Use on-board oscillator
JP3VC1581 disk unit selection: 8 when no jumper set.1-210As fits your setup. I have 3-4 for device number 9n/a
3-49
1-2,3-411
JP4IEC bus reset1-2when set, reset IEC bus with bus reset.
JP5TOD input selection1-250Hz bus signaln/a
2-3Phi2 input (VC1581 setting for WD1770)
not equipedNo input (VC1581 setting for WD1772)*
JP6DD/HD selection1-2Double density disks (DD) only*
2-3Double/High density (DD/HD) selection via control port*
JP7n/a
JP84k/8k Memory selection1-2$4***/$6***n/a
2-3$4***+$5***/$6***+$7****
JP9Memory mapped address selection1-2$54***/$56***
3-4$34***/$36****
5-6$04***/$06***
7-8no memory mapping*

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:
  • The infrared sender is off after reset (reversed signal polarity)
  • Moved the INTR and DRQ lines to bits 7 and 6 respectively on the control port
  • The HD/DD selection is now made via control port and defaults to DD after reset.
  • The drive select signals are switched, to enable drive 0 (SELA) on reset, that is controlled by the VC1581 (via MTR A).
  • ATN can be pulled low via control port, so the board can be used as IEC controller (off after reset)
  • A 47k resistor between CIA pin 3 (PA1) and GND, to simulate a drive ready.
 
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:
JumperDescriptionSettingMeaningVC1581 settingstandard setting
JP1I/O address selection1-2$E8A*/$E8B*don't care*
2-3$E8E*/$E8F*
JP2n/a
JP3VC1581 disk unit selection: 8 when no jumper set.1-210As fits your setup. I have 3-4 for device number 9n/a
3-49
1-2,3-411
JP4IEC bus reset1-2when set, reset IEC bus with bus reset.
JP5TOD input selection1-250Hz bus signaln/a
2-3Phi2 input (VC1581 setting for WD1770)
not equipedNo input (VC1581 setting for WD1772)*
JP6DD/HD selection1-2Double density disks (DD) only*
2-3Double/High density (DD/HD) selection via control port*
JP7Connector for infrared LEDs.
JP84k/8k Memory selection1-2$4***/$6***n/a
2-3$4***+$5***/$6***+$7****
JP9Memory mapped address selection1-2$54***/$56***
3-4$34***/$36****
5-6$04***/$06***
7-8no memory mapping*

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.

Last modified: 2006-11-26.

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