One ROM - The Most Flexible ROM Replacement for Retro Systems
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One ROM – The Most Flexible ROM Replacement for Retro Systems

Price range: £10.00 through £12.00

One ROM is the most flexible ROM replacement for your retro systems.

Update: Only 2xIce One ROMs remaining on this store – all items out of stock on ebay listing.  Get ’em while you can!

Note: These are non-USB versions, requiring an external SWD programmer to use.

One ROM includes tons of features, including multiple ROM images to switch between at either boot or run time, the ability to serve up to 3 ROM sockets from a single ROM, instrumenting your retro system’s ROM accesses, dynamic ROM image updating and many more.

This 24 pin version of One ROM replaces 8KB/4KB/2KB ROMs found in machines like the Commodore C64, VIC20 and PET, the TI-99, Coco2 and many, many more.  It is the same size at original ROM sockets, so there are no issues fitting them in your existing system.

There are two variants of One ROM available:

  • ❄️Ice❄️ – based on an STM32F411RET6
  • 🔥Fire🔥 – based on an RP2350A

One ROM runs open source firmware.  Some technical skill is required to build and flash the firmware, using an SWD Programmer (not included) – so only purchase a One ROM if you are comfortable you are capable of this.

Free shipping to the UK.

If you are ordering from Europe (inc Norway) I strongly recommend ordering using the ebay listing instead.  While prices are slightly higher on ebay (to cover ebay’s fees), ebay will normally collect local sales tax at point of sale, meaning you will not be charges import duties and additional fees when your One ROMs are delivered.

If you are ordering from the US I recommend ordering here.  I deal with the custom fees on your behalf with Royal Mail, so you shouldn’t have to pay anything else to receive your package.  This is somewhat experimental, though!

If you are ordering from Canada, there may be a delay.  Royal Mail has suspended deliveries to Canada due to postal strikes (in Canada?).  You are welcome to order and I will ship when I am able to.

For more details, see the detailed description below, and the github project page.

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Description

I developed One ROM to be the most flexible ROM replacement for my retro systems, and want to share them with other retro enthusiasts.  I sell these at close to cost price, with a slight premium to cover selling fees, returns, etc.

You are welcome (in fact encouraged!) to have your own One ROMs manufactured – all of the hardware files are open source, and available on the github project page.  You can even modify the designs and sell them for profit if you wish.

Features:

  • Supports PETs, VIC-20s, C64s, 1541s, IEEE drives, TI-99, Coco2, etc.
  • Same footprint as original ROMs – doesn’t overhang the socket like other solutions.
  • Quick programming- just connect 3 wires and `make run`. Takes 5-10s to build and flash.  No programming jigs necessary.
  • Use a $5 programmer (e.g. Raspberry Pi Pico) – no expensive EEPROM programmer required.
  • Reflash in situ – no need to remove the ROM from the host when reprogramming.
  • Software configurable chip select behaviour – no hardware jumpers required.
  • Stores up to 8 (Fire) or 16 (Ice) ROM images of different sizes and chip select configurations. Image selectable via jumpers.
  • Replace multiple ROMs with one ROM – a single One ROM can replace up to 3 original ROMs at the same time e.g. all of C64 kernel, BASIC, character set.
  • Dynamic bank switching – switch between ROM images on the fly, e.g. different char ROMs.
  • Hackable at runtime – change the ROM images being served and access telemetry from the ROM at runtime using Airfrog or other SWD probes.
  • Images combined automatically – no need to manually build up your own larger PROM image containing multiple retro ROMs.
  • Open source software and hardware – make and flash your own One ROMs and modify the firmware.

The Fire and Ice variants are very similar, with the following key differences:

  • Ice has tolerance for voltages up to 7V in case your retro system has a dodgy voltage regulator.  Fire only supports voltages up to 5.5V.
  • While Fire has more flash storage, it only has 3 image select jumpers, allowing for up to 8 images to be selected at boot time.  Ice can store and select between up to 16 images.
  • Fire is based on a faster microcontroller, so may support additional systems or features in future – however, this is not guaranteed.

I use both in my retro systems.

I am currently shipping hardware revisions:

  • F – Ice
  • A2 – Fire

All One ROMs are shipped with a set of C64 KERNAL, BASIC, character and dead test ROMs installed, but can be reprogrammed to serve any 2364/2332/2316 ROM image, including the original ROM’s specific mask programmed chip select behaviour, using a SWD programmer.  You can use a Raspberry Pi Pico, Raspberry Pi Debug Probe, ST-Link or many other SWD programmers to program One ROM.

These One ROMs have the pins to insert into the retro system’s ROM socket pre-soldered.  The programming and image select jumper pins are not soldered – extra pins are supplied with each One ROM for you to solder yourself.  This keeps shipping prices lower and you only install the pins you need – it is possible to program One ROM without installing the programming pins, by inserting the programmer’s pins in the hole.

All One ROMs are shipped inside a robust 3d printed case to avoid damage to One ROM and the pins during shipping.

See the github project page for more details.

Additional information

Variant

Ice, Fire

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