Closed SukkoPera's C16/+4 Accessories: RAM Expansions, Carts & Joystick Adapters

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SukkoPera

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Since my first computer was a Commodore 16, I really had to design some hardware for it :).

For each item you can either buy the PCB alone, or the PCB plus a kit with all the components you will need to build the accessory. Either way, you will have to DIY, I will not be selling pre-built devices.

Note that some items require the soldering of some SMD components in the 0805 package. For those who are not comfortable with that, I am offering to pre-solder them for free. If you require this service, please specify it in your order.

OpenC16RamExpansion
OpenC16RamExpansion is an Open Hardware 64 Kb RAM Expansion board for the Commodore 16.

Foto%2005-01-19%2C%2022%2009%2036.jpg


I guess this is a much desired item, but unfortunately AT THE MOMENT THIS EXPANSION DOES NOT WORK ON EVERY C16. At least, not out-of-the-box, there are workarounds but they will all require internal modifications to your computer, which are either not reversible or not easy to perform. This is not due to a fault in my project, but rather to internal shortcomings of the original C-16 design. Feel free to give suggestions on the project page on github if you want. So BUY AT YOUR OWN RISK!

Note that these kits are not suitable for the faint-hearted, since they require soldering some surface-mount components (0805 package).

Kit contains:
  • 4x100nF 0805 Capacitor
  • 2x16-pin Socket
  • 2x74LS257 IC (or 157, they are interchangeable)
  • 2x18-pin Socket
  • 2x4464-type 64Kx4 RAM IC

Prices:
  • PCB: 3.00€
  • Kit: +8.00€

OpenC16Cart
OpenC16Cart is an Open Hardware 8/16/32 KB Cartridge for the Commodore 16, Plus/4 and the rest of the Commodore 264 family. For 32 KB images you will need to use two (E)EPROMs.
Foto%2005-01-19%2C%2022%2009%2048.jpg


This kit requires the soldering of two 0805 SMD resistors.

Kit contains:
  • 2x100nF 0805 Capacitor
  • 12x3-pin Header Strip
  • 10xJumper Cap
  • 2x28-pin Socket

Prices:
  • PCB: 3,00€
  • Kit: +5.00€
  • With Machined-Pin Socket: +1.00€ each
  • WinBond W27C512 EEPROM: +4.00€ each

OpenRomSwitcher
OpenRomSwitcher is an Open Hardware adapter PCB that allows the use of a 27xxx EPROM in place of a smaller (E)PROM. This is useful, for instance, for replacing the KERNAL and other ROMs in Commodore 16 home computers. It supports up to 8 different ROM images that can be selected through switches.
render-top.png


This kit requires the soldering of three 0805 SMD resistors.

Kit contains:
  • 3x10K 0805 Resistor
  • 3x0 0805 Resistor
  • 2x14-pin Header Strip
  • 1x28-pin Socket

Prices:
  • PCB: 3.00€
  • Kit: +2,00€
  • With Machined-Pin Socket: +1,00€
  • WinBond W27C512 EEPROM: +4,00€
  • 1xSPDT switch: +0,50€
  • 4-core wire (30 cm/1 ft): +0,50€

OpenC16JoyAdapter - SOLD OUT
OpenC16JoyAdapter is an Open Hardware Adapter that allows using a Commodore 64/Amiga joystick on a C-16, Plus/4 and the rest of the Commodore 264 family.
Foto%2005-01-19%2C%2022%2010%2035.jpg


Kit contains:
  • 1xDB9 Male Connector
  • 2x2-pin Header Strip
  • 1x8-pin 90-degree Header Strip
  • 2xJumper Cap
  • 1x5x10k Resistor Array
  • 1x100nF Ceramic Capacitor
  • 1x74LS244 IC
  • 1x5x100R Independent Resistor Array

Prices:
  • PCB: 3.00€
  • Kit: +5.00€
  • 8-pin Mini-DIN male connector: +2.00€

Note that to complete this adapter you will need to make a 8-wire cable cable thst goes from the 8-pin header to the Mini-DIN connector. Mini-DIN connectors are not included in the kit and sold separately, and they are quite tricky to solder. On the other end, you can solder the cable directly to the board, if you prefer.

Payment methods accepted: PayPal Family & Friends (or add commissions), Bank Transfer, Satispay (for Italian buyers)

Items will ship worldwide from Italy. All shipments will be trackable and at cost. As a rule of thumb, shipping for up to two-three kits (total weight up to 100 grams) should be 4,30€ to Europe, 5,20€ to the US and 7,10€ to Australia. Add 6€ for tracked & signed for. Ask for exact quote.

Items are also on sale elsewhere.

Please note that I designed all of these boards primarily for my own use. I am open to suggestions and (constructive) criticism. All of my projects are Open Hardware, feel free to check out the KiCad design files on GitHub.

There is more to come, but this is it for the moment. Feel free to ask any questions.

My Sales:


 
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Well, you should show some example pics of your OpenC16RamExpansion and at least one motherboard with this expansion.
 
Items still available, please note that this is my last shipping week before holidays. The activity will then resume in September.
 
Payment received from Tumi81.

OpenC16JoyAdapter is now sold out. I don't have any plans to make more at the moment, but should anybody need them, let me know and we'll see.
 
I guess this is a much desired item, but unfortunately AT THE MOMENT THIS EXPANSION DOES NOT WORK ON EVERY C16. At least, not out-of-the-box, there are workarounds but they will all require internal modifications to your computer, which are either not reversible or not easy to perform. This is not due to a fault in my project, but rather to internal shortcomings of the original C-16 design.
The 'modification' is required to disable the onboard 16k of DRAM in the C16 and I know of at least 2 ways to do that easily and in a reversible manner.

The first one is to put a switch on pin 1 of the two 4416 of the C16, toggling between ground and 5Vdc - by default they are grounded.

The second one is to use a modified 48 pin socket under the TED which will disconnect CAS from the mainboard and have it on a separate wire going to the 64k RAM cartridge. Just put a pull-up resistor on the 64k RAM cartridge which pulls-up the CAS line of the C16 board.

Other note: On your 64k RAM cartridge is a pair of 74LS257. Replace them with more modern 74HCT257 and your cartridge will consume much less power
 
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@spcbm: Will PM you ASAP.

@eslapion: Thanks for your thoughts, they are much appreciated.

Solution 1 is well-known but it's not really easy to do, as it requires desoldering the whole chips to get a "clean job".

Solution 2 is more interesting, but I find this would be ok if we wanted to make a board to be sandwiched between the TED and socket, carrying the RAM chips and whatever is needed. An internal expansion that cannot be removed, I mean. This is because the machine would no longer work if the expansion is unplugged at that point (unless you also bring out the /CAS signal going to the chips, add a switch and whatever).

The modification I am looking for would ideally be to add the missing circuitry so that the machine will use the expansion correctly, but so that the machine will still work correctly if the expansion is unplugged, without any manual intervention. Ideally, this mod would also be easy to install and it shouldn't require to cut any tracks. But I guess the latter is impossible to achieve, as the whole thing implies the splitting of the /RAS (or /CAS) signal in two, one addressing the internal chips and one going to the cartridge slot. Equations are easy:

!ras_int = !ras & !(!a14 & !a15)
!ras_ext = !ras & (a14 | a15)

The point here is to rewrite these in order to use the least possible logic gates (which would be just one... at the moment I have it down to a gate + a transistor inverter but maybe we can do better) and to make sure that the memory detection routine in the ROM always does the right thing. One day I'll look into this accurately, at the moment I am focusing on Amiga projects. But maybe I should add your hints in the docs for the expansion, I'll consider it.

About the HCT vs LS: yes, of course. Whoever builds the expansion has the freedom to do that (I personally did it). That should probably made clearer in the docs as well.

Feel free to give more suggestions if you wish :). Maybe raise an issue on the github page, even.

EDIT: I think it can be done with a single 74253 or 4052.
 
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