Category: Hardware Design

Commodore USB Interface Thoughts

The USB interface has become the ubiquitous interface for all kinds of peripherals, from file storage to cameras, wireless adapters to input devices. I wonder if there would be interest in a USB interface for Commodore machines, and how “intelligent” it would need to be. For example, I could easily design a “dumb” interface that simply maps the USB electrical interface into the C64/C128/VIC address space, but then each developer would be required to implement all USB protocol functionality. On the other hand, a more intelligent interface would help developers, but would cost more and some development would still be necessary, as many less common USB devices would require custom drivers to implement high level functionality.

Still, the idea seems a sound one. If the right balance is chosen, only software development would be required to use newer USB devices on the C64/C128. Software is much easier to develop and share, and if there are enough owners, it would be worth it to add support for USB devices in programs like GEOS, etc.

I’d appreciate any thoughts readers might have. Is this something you would find useful?

24 Pin and 28 Pin Headers Arrive

Finding economical 24 pin and 28 pin IC headers for adapter boards like ROM-el has been a significant challenge. DigiKey and Mouser stock on forked post headers, which are mainly designed for attachment of wires, not soldering to a PCB daughterboard. Aries Electronics offers the correct product, but they are almost $2.00 per piece, which is not sustainable.

Recently, I ventured into bulk purchasing of some components, like the 22/44 .100″ connector for C64/C128 cartridges, and the 6/12 .156″ connector for the C64/C128 cassette port. Given the success, I recently ordered 1000 each of some 24 and 28 pin IC headers, at much better prices. Of course, since I have no immediate need for so many units and I suspect others have the same issue sourcing these items, I’m soon placing them in the store.

Thus, if you’re in need of 24 or 28 pin IC headers, machine pin, low profile, check the store in a few days.

64NIC+ Ethernet Cartridge Order

When the Cincinnati Commodore Computer Club approached me in late 2008 to design a low-cost ethernet cartridge for the C64/C128, I underestimated the interest. Not only has C4 sold out of their stock, but mine is gone as well.

I’m happy to report another order has been made, and should be available in a month or so. No changes, though I may take the lead time to see if I can source some cheap EPROMs for the ROM slot on the cartridge and see what I might be able to bundle in the ROM.

At some point, I’d prefer to improve on the design, but it may very well be that this design is “good enough” for what people want to do.

JiffyDOS Production Units

JiffyDOS Production Unit
JiffyDOS Production Unit

After many months of preparation, JiffyDOS production ROM overlays are finally ready for distribution. The system utilizes the ROM-el FLASH-based ROM emulator, allowing the units to be fully assembled before programming.  Units should be available shortly for sale in the online store.  Click on the picture for a larger view.

Anyone want to MasC=uerade?

MasC=uerade PCBBased on a customer request, I’ve designed a small adapter card that will allow C64 cartridges to be used in the Commodore VIC-20. The design is not finished, and suggestions are appreciated. Switches allow the IO and BLK select lines to be configured per cartridge. Barring any major changes to the design, I hope to have units available early 2010.

ROM-el testing complete

23XX and 23XXX ROM-el
23XX and 23XXX ROM-el

Aries was backordered on the required 24 and 28 pin headers needed to finish testing, and the order just came in this past week.  Thus, I finally had a chance to solder and test the units.  Testing went well, and I can program the units with my Willem programmer.  Originally designed to hold a 29EE512 64kB EEPROM, I found a good price on Atmel AT49F001 128kB 5V Flash, so I made the necessary adjustments and tested with the new memory.  Testing went well, so I am releasing the design to production.

I have noticed one issue that I need to address.  Some CBM units have an RFI shield that doubles as a heat shield.  To perform the latter function, metal “fingers are stamped out of the shield that press on the top of the ICs.  I need to ensure the metal shield/heat sink does not contact any of the pins on this unit.

ROM-el in production!

I’ve initiated phase 1 of ROM-el production, scheduling the PCB design for production and shipment.  ROM-el will be completed in 3 phases:

  1. PCB manufacture and shipment of 2 bare boards
  2. Manual assembly and testing
  3. Release PCB for assembly and shipment

This is typical for new designs, for the following reasons:

  • Given the low cost of production boards, it’s cheaper to make a production board run instead of an initial prototype board run.  In the best case, the board is operational and no prototype board costs are incurred.  At worst, the board must be “spun” once more, but the total cost does not exceed a prototype + production run cost.
  • Shipping 2 boards ahead of time permits verification of the design before assembly.  The boards are shipped at no cost by “piggybacking” them on a previous order that is nearing completion.

Normal turnaround is 10 business days (2 calendar weeks), so I expect boards around July 12th.

To save costs in creating the SMT stencil and the boards themselves, I “merged” 4 designs into one set of files for the PCB house using Gerbmerge.  I struggled to install the program in Windows, which was unsucessful.  The application has some dependencies, one of which requires a C compiler.  The Windows install of the dependency assumes Visual C++, which I do not own.  After wasting a few hours, I installed on the local Linux server, which was trivial.  The application is very straightforward, and I was able to create a minimal merged set of files in a few minutes.  Thus, I will be receiving 100 units of:

  • ROM-el 2364
  • ROM-el 23128/23256
  • 2364Adapter (simple DIP style 24-28 pin adapter
  • 6540Adapter (CBM-Hackers folks asked for this design, which has not been tested)