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Commodore PET Projects - petSD+

petSD+ - Alternative Options

 

 

The devices shown on this page are not the only alternatives to petSD / petSD+ that are available for adding a modern day "disk" interface to a PET, but they are the ones that look most interesting to me and are SD card based.

 

pet microSD - Designed by Dave Curran

The difficulties in getting hold of a PETDisk (see below) drove Dave to designing and building a version of his own as described on his blog. Dave generously donated a fully functional board to me that I have used while preparing the feature comparison table below - thanks Dave!.

Whilst a PETDisk "clone" would probably be the lowest cost option for adding an SD based "floppy drive" to a PET, the functionality of the PETDisk firmware is very limited, Steve Gray and Mike Naberezny suggested that Dave have a design that uses the sd2iec firmware used in petSD, petSD+ and petSD-duo, so Dave has developed pet microSD.

Dave's draft PCB design for pet microSD.

This design is a slightly modified version of the original petSD, using a 74LV125A buffer and a filtered 3.3V supply.

The board uses surface mount versions of the ATmega1284 and bus drivers, to minimise the board size, the bus drivers and 3.3V supply are placed on the reverse side of the board.

Because of the difficulty that hand soldering would present to the average hobbyist, Dave intends to make pet microSD available as a finished product only.

The first assembled pet microSD
"Solder side" of the board, showing the bus drivers and 3.3V supplies
Version 1.2 of pet MicroSD, they have changed a bit, they've gone blue!

There are also a few other minor mods, most notably the package of the 74LVC125A buffer has been changed to give more room around the other components. The power LED is also now blue to match, green for activity, red for error.
The back of the board hasn't changed much, the polyfuse is now on the back, and the space to write the serial number and firmware have been moved.    
To go with this, there is now a board which taps the power from the datasette connector, and now includes a pass through to allow the datasette to be used at the same time.  

[Dave has kindly made a number of the datassette boards and its design files available to me and I will now be offering a similar power board for petSD+.]
Dave's perMicroSD connected to a PET 4032, showing the IEEE-488 bus connector and datassette power connector with datassette pass-through.
In September 2015, Dave added a couple of new versions to the pet Micro SD range . . . . .

This version, which mounts on the PET edge connector in a similar way as a ZX81 RAM pack and takes up hardly any space at the rear of the PET.
And this one, which mounts on the PET edge connector but has the PCB located internally.

In both cases, Dave now avoids the 5V rail, and now taps the 9V unregulated supply from an internal connector and uses a small DC-DC converter on the PET microSD to generate it's own 5V rail.

He has also gone back to a single sided board design, "to make my life easier".
 
To help a prospective purchaser choose from his range of different pet MicroSD versions, Dave has created a model selection matrix, available on his site here    

 

TS - Designed by Dave Curran (a work in progress)

With a view to creating a minimal cost version, but still having better Commodore DOS support than PETDisk, Dave is considering the possibility of enhancing his PETDisk inspired board and developing TS-SD

Dave's draft PCB design for TS-SD.

 

petSD-duo - Designed by Nils Eilers (a work in progress)

The duo is basically an advanced and enhanced petSD. A slave MCU (ATmega 328P) is attached to it via I2C and controls the LCD display (192 x 64 pixels) and the rotary encoder. This allows navigation through sub-directories and disk images and present them with a Commodore font with all the special characters found there, 8 lines and sufficient columns.

Nils is currently working on petSD-duo, but the projected price just for the components is becoming a potential issue and there is still quite a bit of work to do before it could be released as a finished article.

 

I think that it is safe to say that, in the short to medium term, petSD, with some minor revisions, is the best (only?) option.

 

A photo (from Nils' Flickr page) to show how the finished article may look.

 

PETDisk - Designed by bitfixer

"PETdisk is a simple storage device for the Commodore PET series of computers, using a microSD card for mass storage and uses the PETís IEEE-488 port." Documentation, schematics, and source code can be downloaded from the PETDisk website that can be used to build your own, the site also has an ordering page where self-assembly kits of ready made units can be purchased.

 comprises two modules, one that hosts a micro-SD card and connects to the IEEE port and one that connects to the cassette port for loading & saving to tape and for providing USB power to the other module.
PETDisk was the first floppy drive emulator that I found for the PET and looked very interesting, I tried to e-mail the seller a couple of times without success, you may have more luck. but I then came across petSD.

 

Feature Comparison

Name (links to webpage) PETdisk TS-SD petSD pet microSD petSD+ petSDduo
Contact (links to e-mail address) bitfixer Dave Curran Nils Eilers Dave Curran Nils Eilers Nils Eilers
Enabling technology ATMega168 ATmega328P ATmega 1284P ATmega 1284P ATmega 1284P
ATmega 1284P
ATmega 328P
MCU Clock Speed MHz (Type) 8  (RC) 16 (RC) 18.432  (Xtal) 18.432  (Xtal) 18.432  (Xtal) 18.432  (Xtal)
Firmware supported
PETDisk
 (bespoke)
 ts-sd
 (bespoke)
sd2iec
XD-2031
NODISKEMU
(sd2iec fork)
NODISKEMU
(sd2iec fork)
"emily"
(bespoke)
Flash programming SD Bootload ISP (6-pin) ISP (6-pin)
SD Bootload
ISP (6-pin)
SD Bootload
ISP (option)
USB Bootload
2 x ISP (6-pin)
Firmware licence (Ref. 1 23 4 5 6) GNU GPL GNU GPL2 GNU GPL2 GNU GPL2 GNU GPL2 BSD
PET IEEE-488 Interface connector(s)
PET Edge PET Edge
IEEE-488 &
Pin header
PET Edge or
Pin header
IEEE-488 or
Pin header
IEEE-488
Mounting options  Internal
   External
 
 80xx-SK only
 
 
 
 
IEEE-488 Bus Drivers
Device addresses 8, 9, 10, 11 8, 9, 10, 11 8, 9, 10, 11 8, 9, 10, 11 8, 9, 10, 11 8, 9, 10, 11
Power source Tape port
Tape port or
External (5V)
External (5V)
Tape port or
Internal (J11)
Tape port or
External (5V)
External
9-24 VDC
Storage medium Micro SD Micro SD SD Micro SD SD SD
Storage card interface Diode 74LVC125A 74HC4050 74LVC125A 74LVC245A
74HC4050
74HCT125
Format FAT 32 FAT 32 FAT 12/16/32 FAT 12/16/32 FAT 12/16/32 FAT 12/16/32
Long filename support
Sub directories Y (beta)
Image file support D64/D80/D82 D64/D80/D82 D64/D80/D82 D64/D80/D82
CBM DOS Compatibility

Max

      File Types 5
      Native Commands 30
 
2
6
 
?
?
 
?
?
 
2
29
 
?
?
 
?
?
Additional functionality
      Real time clock
      USB Interface (virt serial port)
      Ethernet
      Tape to SD transfer
      IEC (IEEE-488 Serial) mode
 
 
 
(limited)
(limited)
 
(FTDI port)
 
(FTDI port)
 
User Interface Blind Blind Blind Blind LCD or Blind LCD
Prices Standard kit of parts
  Fully Assembled
Options SD Card
  (Without) Real Time Clock
  USB Interface
  Ethernet
  Without LCD
  Internal mounting
$35.00
$55.00
$10.00
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Cost

Cost

 

Functionality

Functionality

Prices as of June 2015, exclude shipping and any applicable taxes

$, $$, $$$ indicate projected relative prices

Using exchange rate £1 = $1.50

Availability 2Q 2015 4Q 2015 (Obsolete) Now Now Future

 

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