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Commodore PET Projects - petSD+

petSD+ News


petSD+ Version 1 Prototype

(minus the LCD)

petSD+ Version 2 Prototype

(minus the LCD and clock module)


26/06/2020 * * * Issues with NODISKEMU and REL Files * * *

Quoting from the NODISKEMU firmware README file . . . "Partial REL file support is implemented. It should work fine for existing files, but creating new files and/or adding records to existing files may fail. REL files in disk images are not supported yet, only as files on a FAT medium." 

Note: this restriction also exists in other devices based on SD2IEC firmware

29/08/2019 Possible Firmware Bug


I am convinced that there is a bug in the NODISKEMU firmware that prevents proper initialisation of petSD+ at start-up with SOME MCUs. I think that I have eliminated all other possibilities and with the status of NODISKEMU now being unmaintained, this issue is unlikely to be fixed.

If you purchase a petSD+ Version 2, there is a high probability that the device will require a reset on power on before it starts up properly. (See here for details)

If you cannot live with this minor, but nevertheless undesirable, behavior, then please think twice before ordering. Unfortunately, I am unable to fix this issue and cannot accept returns for devices that exhibit this behavior.


The petSD+ firmware (NODISKEMU) is now unmaintained. Nils is no longer developing or supporting petSD+ / NODISKEMU Follow the link above for details and the implication of this development  

05/06/2019 3D Printed Case for Version 2.4 PCB

Luis Fernando Salazar, has created a really neat 3D printed case for petSD+ Version 2. For full details about the case and how to contact Luis to order one see this page  

13/05/2019 Version 2.4 PCB - Case Options

The case options available for Version 1.x of petSD+ are not suitable for Version2.x so have been removed from the Ordering Page to avoid confusion. For any petSD+ owners who may be interested, the information is archived below :

Discontinued Case Options
Case, including PCB supports, bolts, etc. (Ordered on request)  
£ $ 1 Euro 2
5 7 6
We had planned to offer a case option for petSD+, based on the same style as used for the original petSD. This is my "Photo shopped" mock-up of how petSD+ might look with the LCD display fitted to the case that Nils had in mind ( stock no. SD 10 GR HALB/SD 20 GR HALB).

Unfortunately though, although the proposed case for petSD+ is workable, Nils found that the installation was very tricky and time consuming, so it was not really practical to offer the case as an option.

For units with the display, not having a case is not really a problem as the PCB supports raise the bottom of petSD+ off the desk and make it level. For units without the display, you might like to think how the petSD+ will sit on your desk, particularly as the battery holder is on the underside of the PCB.

Nils did buy a few cases with a view to making them available as standard, now that we are not going to do that, I have a few spares. The bottom half of the case could be used without modification to hold the PCB and if you wanted to spend some time on it, you could add the holes required in the top half of the case to completely enclose petSD+ if you wanted to.

I can offer the cases, including the PCB supports (shown below), for £5 ($7, Euro 6), available in grey (shown) or black.

(These cases are suitable for petSD+ Version 1.x only.)

Alternatively, if you just need a set of the PCB supports, including 4 x M3 spacer bolts, 4 x M3 distance sleeves and 4 x Philips pan-head screws, I can supply a set for £1.50.
Rainer Fritz has mounted his petSD+ in a very similar case, available from Conrad Electronics as part number 521035 - 62. It looks to be the same case, split 50:50, rather than the 1/3 : 2/3 of the cases that I have available.

Photo courtesy of Rainer Fritz
Rainer's petSD+, showing the rear of the case with the IEEE-488 connector and power input lead.

Photo courtesy of Rainer Fritz
And a view from the front, showing the controls, indicators and SD card slot

Photo courtesy of Rainer Fritz
Third Party Case Option - Suitable for petSD+ Version 1 Only

For Information Only

Juergen Krieg has let me know that he has sourced a nice acrylic case  for his petSD+ from Michael Schön (

Michael is now making the case available though his webshop. The case is priced at €19.00 including VAT (shipping extra). It's more expensive than the cases that I am able to offer, but is custom made for petSD+, so fitting it is a much easier process than modifying one of my off-the-shelf cases.

Photos courtesy of Juergen Krieg

To purchase the acrylic case, please contact Michael through his webshop


30/03/2019 Version 2.4 PCB Now Available

The SD card slot used in petSD+ version 2 has been discontinued by the manufacturer. The replacement card slot that we are now using has a slightly different footprint which has necessitated a minor change to the PCB. There are also few minor layout changes

29/01/2019 Potential Issue with PET IEEE-488 Adapter

A small number of IEEE-488 adapters shipped between July 2017 and January 2019 may have been shipped with a construction error. If your adapter has an empty 3 position jumper block, or a jumper block with no link fitted, marked "IFC" at the side of the IEEE-488 connector, please contact me for further details of a potential issue with your adapter. It is not certain that any adapters actually have this issue, but it would be prudent to check that yours does not.

26/01/2019 Price Increase

There will be a small increase in the price of petSD+ kits from 1st February 2019 Orders placed prior to this date will be charged at the old prices. The prices on this page have been updated with the new prices. (Increase is £5 on kits, the price of assembled units is unchanged)

25/01/2019 Version 2.2 SD Card Slot Obsolescence

The SD card slot used in petSD+ Version 2.2 is now obsolete! I have a limited number of version 2.2 boards available and enough card slots to finish their construction, but a new card slot needs to be sourced which will require a change to the PCB layout. Nils is currently working on the required changes and a Version 2.3 board will likely be released in the next few weeks. Once the current orders have been filled, I have enough parts to build another 8 petSD+s. If you are in  hurry to get a petSD+, please order now. I will use the last of the parts for the current design on a "first come, first served" basis.

03/09/2018 petSD+ Version 2 PCB Modification

There have been a few minor tweaks to the layout of the PCB, the main change is to relocate the LEDs to better suit its installation in a 3D printed case, such as the one designed by Stephan Both    

28/01/2018  Price Increase

There will be a small increase in the price of petSD+ from 1st February 2018 Orders placed prior to this date will be charged at the old prices. The prices on this page have been updated with the new prices. (Increase ~9% on kits, ~4% on assembled units)


petSD+ Version 2 will be available for purchase in 2-3 weeks

I need to work out the final price, but it will not be dissimilar to Version 1. It is my intention that, come 1st February 2018, ALL new orders for petSD+ will be supplied as Version 2. I had intended to discontinue supply of Version 1, but it strikes me that there are possibly two groups of prospective purchasers who may prefer the option of a new Version 1 petSD+.

1.  Existing Users who want a like-for-like replacement/addition to their existing setup

2.  Users who want to purchase the acrylic case manufactured by Michael Schön

If you fit into one of these two groups and NEED a Version 1 petSD+ let me know when ordering.

17/01/2018   Created this new "petSD+ News" page, collating all previous newsworthy items regarding petSD+

10/01/2018   Deluxe LCD Display Update - the new displays have arrived

Note: the new displays use VATN (Vertically Aligned Twisted Nematic) technology, rather than the FSTN technology in the previous ones. In VATN displays, the liquid crystals align vertically when the voltage is zero, this creates a truly black background to the display. When voltage is applied, the liquid crystals shift to a tilted position allowing light to pass through and create a gray-scale display depending on the amount of tilt generated by the electric field.

VATN displays have a super black background, there is no "bleed through" of the backlight that could be seen on the FSTN displays, they have a Super high contrast ratio and the text is noticeably sharper.

This obviously comes at a cost, but if you do want to splash out on one of these screens, you won't be disappointed !

Due to the low volume of sales and difficulty in obtaining them, a number of the LCD colours have been dropped from the "Order" page. I have archived the discontinued options here . . . .

Discontinued LCD Options
Reflective Display Option

To cater for the environmentalists out there, who may be looking to save energy, I have a limited number of reflective LCD displays available. (There is absolutely no truth in any rumors that these were bought in error!)

No longer available
   "Deluxe" Colour Options  
This is the "Green on Black" FSTN display that I am was able to supply.

It is not apparent from the photo, but the colour is very close to the display that Nils sent me, shown above. In fact, I think that I will be using the same supplier that Nils used.

No Longer Available
I can also supply it in what was described as "Yellow on Black", the photo makes it look very yellow, but the colour is actually much closer to Amber on black, very much like the colours of the IBM Portable screen.

For comparison, this is the seller's photo showing the display colour, this is a much closer match to what the display looks like in practice.

06/12/ 2017 No Longer Available
I also bought one advertised as "Black letters, White background". Again, the photo doesn't give a very good representation of the colours, but as it suggests, the display would be more accurately described as "Dark Blue on Pale Blue" although in reality, the blue is not as pronounced as the photo suggests

It is definitely not Black on White, but quite nice all the same.

For comparison, this is the seller's photo showing the display colour, it does appear closer to black and white, but, as I know now, that is down to the quality of the photo, rather than the actual colour.

No longer available


06/12/2017   Deluxe LCD Display Availability & Price

The "Deluxe" LCD Displays are proving difficult to obtain and are now almost twice the price that I paid the last time that I ordered a batch. Orders for the deluxe displays up to order number #72 have been filled but have used up my stock of these screens.

The Green on Black displays proved to be the most popular "deluxe" option, outselling the Amber on Black by about 10:1. Given the low volume of sales of the Amber displays, I will not be restocking these unless specifically requested to provide them (which will result in an 10-12 week delay before I could obtain them).

I do intend to continue to stock the Green on Black displays and have 10 additional displays on back order but the supplier has advised that they will not be shipped until week 6 or 7 2018. I also need to pass on some (but not all) of the additional price to buyers, therefore, the enhanced screen option will now be £12 (previously £7).

If anyone can point me to alternative sources of these displays I would appreciate it. If I can get the displays cheaper, then I will reduce the additional charge.

20/06/2017   Third party case available

Michael Schön ( has created a nice acrylic case for petSD+ and is making it available though his webshop. The case is priced at €19.00 including VAT (shipping extra). You can see a couple of photos on my "Ordering" page or on Michael's website.

The website is in German, use Google Chrome to have the page automatically translated for you, a local copy of the page, translated into English, is available here

27/09/2016   Price Increase Effective 01 October 2016

As I live in the UK, petSD+ prices are quoted, and must be paid for, in UK pounds. Over the past year, exchange rates have dropped significantly, sterling having dropped from ~$1.5 USD or 1.4 Euros in October 2015 to ~ $1.3 USD or 1.1 Euros today.

Since I source most of the parts in Europe or the USA, it has become significantly more expensive for me to make petSD+, but the effective price for most customers has actually reduced from about $105/E91 to around $91/E77 today.

For the supply of petSD+ to remain viable, I need to increase the sterling prices of the kits and assembled units by 10% (less than the 15% exchange rate difference). This change will only really impact the very small minority of customers who are in the UK - international customers will not see any increase over the Dollar/Euro estimated prices on this page - they will just not get as large a currency discount as they have seen over the past year, but will still pay a little less than my estimated prices.

01/06/2016   Status Update

The current version of the firmware for petSD+ now fully supports disk read/write functions and the Real Time Clock, in addition, the LCD can now be used to change the Device Address, change directory and load disk images.

The boot loader is able to re-flash the MCU from a binary file copied to the SD card, no additional user programming of petSD+ is required. The firmware release are compatible with all versions of petSD/perSD+.

A copy of the latest firmware binary file, is available from an auto-generated nightlies page on Nils' site.

A modified version 2 PCB is currently being designed by Nils, but this may take a little while to make it into production. Version 2 is likely to feature enhanced control of the LCD brightness and contrast using PWM and a few other minor improvements.

In the meantime, a slightly modified version "1.2" board is now on order, it corrects a number of minor issues with earlier versions of the board (1.0, 1.1, 1.1a), including :-

  •  the MISO connection issue described in Nils' errata link on his web page. (This issue is only relevant to petSD+ boards that have the ISP port connector fitted which will not be needed by most users anyway).

  • removal of the redundant capacitor, C12

24/03/2016   petSD+ now supports IEC (Serial IEEE-488), i.e. Commodore 64 (requires custom cable)

29/10/2015   A modified Editor ROM with integral DOS Wedge is really a great step forward . . .

Every petSD+ owner should have one! To that end, I have been investigating the possibility of being able to create one and supplying it as an option for petSD+ purchasers. Read the latest developments on this page.

17/10//2015   Component C12 can, and should, be removed from ALL petSD+ devices shipped prior to 17th October 2015.

Provided that you have some basic tools, removal of C12 is straightforward. As C12 is located behind the PREV button, if the LCD screen is fitted it should be temporarily disconnected to allow C12 to be removed - more details here.

If you would have difficulty in doing this yourself, drop me an e-mail and we can try and work something out.



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