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Commodore PET Projects - petSD+

petSD+ - User Guide




Connection / Disconnection
* * * Power OFF the PET/CBM and petSD+ before connecting or disconnecting petSD+ from the computer * * *
SD Card Insertion / Removal
* * Ensure that the Card Access LED (see below) is OFF before installing or removing the SD Card * *

LCD Functions

The optional LCD screen and function buttons provide additional features not available with the "blind" version of petSD+ :

These features described on this page are subject to change as the firmware develops

When petSD+ is powered on or reset, it will display the current firmware revision for a few seconds, before switching to the normal status display. petSD+ is available for use immediately, the timed display of the opening screen does not interfere with normal operation, the device is available for immediate use from the PET or pressing one of the option buttons will invoke the LCD menu.


Diagnostic Display (Offline)
(Requires firmware dated 01-08-2015 or later)

Holding in the Prev[ious] button while powering on or resetting petSD+ will bring up a hardware diagnostic screen as shown.
In this mode, petSD+ is isolated from the IEEE-488 bus and will not respond to commands from the PET.

The Red and Green LEDs will flash alternately whilst in this mode.

The ADC number is the value read from the analogue to digital converter connected to the Prev[ious], Next and Select control buttons.
As well as their primary functions, the buttons, when used in combination, can also perform additional functions programmed in the firmware.

The table shows typical values read / displayed for all combinations of the buttons.

The other fields are the status of the SD slot Card Detect and Write protect switches and the values of the MCU fuse words - "OK" signifying that they set as required.

To exit diagnostic mode, power cycle or reset petSD+.
Prev Next Select ADC
0 0 0 573
0 0 1 774
0 1 0 655
0 1 1 931
1 0 0 607
1 0 1 838
1 1 0 700
1 1 1 1023
Run-time LCD Functions
(Requires firmware dated 26-10-2015 or later)
The Prev and Next buttons have different effects depending on the context of their use in the Menu system, the buttons are either used to move between options ("tab" mode) or to adjust the value within the selected option ("scroll" mode), the Green LED is used to indicate the current button mode; "tab" = LED OFF, "scroll" = LED ON.

When moving between menu options, or between fields on an individual menu screen, the Green LED is turned off. When the user wants to select a particular configuration item for modification, the user moves ("tabs") to the desired item and hits the Select button. The Green LED turns on and the Prev and Next buttons are now used to scroll through the available options or values. When the appropriate value is highlighted, pressing Select will save the chosen value and the menu will return to "tab" mode. At this point, the revised option has been stored in memory only and is not permanently saved until a Save Settings is performed (see below).
If the user does not interrupt the "Welcome" display, once it times out, the LCD will show the device address and its current status in a similar format as that returned from a "real" Commodore disk drive running the Commodore Disk Operating System (DOS) as shown on page 1 of this guide.
An example of the Amber LCD, the display is much better than it looks - the photo is not helped by the fact that the display still has its protective plastic film in place.
After the system has been initialised, display will report the status of any future "disk" commands targeted at the petSD+ device address in a similar way to Commodore DOS returns status messages to the host. In this example, the disk command was successful and its status was reported as OK with zero values in the status code fields.
If the command returns an error, the LCD will display the relevant CBM DOS error string and status codes and the Red LED will flash. The error state will clear when a successful command is entered at the PET and can also be cleared by pressing the Prev button, locate below the LED.
When petSD+ is operating normally, pressing any of the Prev[ious], Next and Select control buttons will invoke the LCD menu system.

While the LCD menu system is in operation, petSD+ is disconnected from the IEEE-488 bus and the Red LED will be illuminated to show the disconnected status.
When petSD+ is disconnected from the IEEE-488 bus, commands issued to it from the PET will generate a "?DEVICE NOT PRESENT " error, when the LCD menu system is exited, the device will again be available for use from the PET.
Save Settings Dialog
(Requires firmware dated 26-10-2015 or later)
When the user changes settings, such as the Device ID, they are given the option to save the changes to the non-volatile EEPROM area, if the settings are not saved, they will be reset to the stored configuration when petSD+ is reset or powered off.

Note: when the user elects to Save Settings, ALL of the configurable settings are written to the EEPROM - it is not possible to save only individual configuration items.
Change Device ID Number
(Requires firmware dated 26-10-2015 or later)
Selecting the Change Device Number option displays this screen.
Use the Prev & Next buttons to cycle through the legal value of 08 to 30, holding in the button scrolls through at fast speed, use Select to set the new ID.
(Use Save Settings as desired.)
Display and Adjust the Real Time Clock
(Requires firmware dated 28-10-2015 or later)
Selecting the Set Clock option displays this screen.
The cursor is initially placed at the Day field, use the Prev & Next buttons to cycle through days 01 to 31, use Select to accept the day and move onto the Month field and so on. The system is leap year aware, selecting dates such as 29th February in a non-leap year, or 31st June in any year will jump back to the Day field for correction.   
Pressing Select when on the Seconds field will expose the options to :
Write to RTC Update the RTC chip
Edit again Return to the clock edit line
Abort Quit without saving
Display and Change Current Directory / Image File
(Requires firmware dated 06-01-2016 or later)
The Browse files option now allows you to browse the SD card, change directories and load image files using the Prev, Next and Select buttons
The Browse files option :
    Abort leaves the Browse menu
    Change to parent Dir moves up a level in the directory tree
    The Prev and Next buttons scroll the directory list and and Select changes to the
    marked directory or image file.
Browsing to the bottom of the current directory
Notes :

The current firmware does not prevent you from trying to move above the top level directory, no damage is done, but the device reports a "Not Found" error.

As described above, the LCD menu allows the user to change directories and load image files by selecting the appropriate entry in the directory listing. This is made possible by NODISKEMU's ability to support directories in the same way as CMD disk drives did - that is, disk directories and image file support is implemented in the device firmware. Commodore BASIC is not aware of the directory structure, and BASIC commands such as directory just return a list of files that appear to the system to be in the root directory of a floppy disk.

Whilst it would be ideal to be able to load a program file using the Select button on petSD+, this is currently not possible and would require significant modification to petSD+ to implement it. To perform an action on the PET, such as initiating a file load, petSD+ would need to be able to flag up a request for action to the computer. Although the IEEE-488 standard includes an interrupt line (SRQ = service request) and this line is internally attached to the CBM/PET, the KERNAL ignores it completely. It would be possible to patch the KERNAL or add functionality to Steve Gray's Editor ROM, to provide Operating System support for remote file load requests, but the petSD+ MCU does not have spare I/O to support the SRQ line.
Toggle IEEE-488 / IEC Mode
Requires firmware dated 15/03/2016 or later)
From the main menu, scroll down to the second page of the menu until you see the
    "Select IEC/IEEE-488" option
Press Sel to select that menu entry

A submenu with the two entries IEC / IEEE-488 will appear.
Position the cursor on the required option and press Sel

    "IEC" for serial interfaces, e.g., the Commodore 64, or
    "IEEE-488" for parallel interfaces, i.e., Commodore PET
The Save Settings dialogue will be displayed
Position the cursor on the required option and press Sel
Selecting yes will save the setting to Flash and will persist through reset or power cycles





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