C64 Reloaded MK2
| |
| Caption | The fully-assembled C64 Reloaded MK-II PCB – all legacy chips have been installed |
|---|---|
| Type | Drop-in replacement motherboard |
| Designer | Individual Computers (Jens Schönfeld) |
| Manufacturer | Unknown |
| First released | December 2016 (first pre-order run) |
| Latest revision | Batch 2 production (2018) |
| Operating voltage | Single 12 V DC input (2.1 mm barrel) – on-board SMPS generates +5 V, 9 VAC-equivalent and SID/VIC analogue rails |
| Layers / PCB | — |
| Compatibility | Commodore 64 / 64C replacement in new or original cases |
| Features | — |
| Model No. | — |
The C64 Reloaded MK-II (often written C64R MK2) is a modern, factory-made Commodore 64 main-board produced by German hardware house Individual Computers. It retains full electrical compatibility with Commodore’s 8-bit chipset while replacing the fragile analogue power regulators, obsolete PLA and timing circuits with CPLD logic and efficient switch-mode converters. Unlike FPGA recreations such as the Ultimate 64, the MK-II still uses original MOS custom chips supplied by the user.
📦 What’s in the box
[edit | edit source]- Finished four-layer PCB with every passive/logic part soldered and QC-tested.
- Five professional ZIF-sockets for the legacy ICs:
CPU (6510/8500) VIC-II video (6567/6569/8565/8562) Two CIA interface chips (6526/8521) One or two SID sound chips (6581/8580) – stereo is optional
- Dual colour power LED, barrel-jack PSU lead and RF-shield stand-offs.
The buyer contributes only the vintage chips, keyboard, case and a 12 V notebook-style power brick.
🔑 Key features
[edit | edit source]- Universal video
- PAL and NTSC crystals are fitted; a CPLD-controlled PLL and software menu let you swap standards without moving jumpers.
- Integrated PLA replacement
- A Xilinx XC9500 CPLD implements the entire PLA logic with cycle-accurate timing.
- Eight switchable Kernals
- 512 kB flash stores the original CBM Kernal, JiffyDOS and six user images; a tiny push-button (or RESTORE-long-press) selects the active bank.
- Modern power architecture
- On-board DC-DC converters create cool-running +5 V and the 9 VAC-derived rails; the board therefore needs only one 12 V supply and tolerates 7-20 V input.
- Dual-SID stereo mixer
- Independent analogue rails for 6581 (12 V) and 8580 (9 V) – any combination is allowed, with software-selectable base addresses.
- IEC fast-loader safe
- Strong, ESD-protected bus drivers allow hot-plugging of 1541-II/1571 drives and modern SD-based devices.
A micro-USB service port exposes an I2C-driven configuration menu where clock speed, drive strength, video delay and SID mixing can be fine-tuned from a PC utility.
🛠️ Required donor chips
[edit | edit source]| Socket | Function | Notes |
|---|---|---|
| U1 | 6510 / 8500 CPU | All speed grades supported |
| U2 & U3 | 6526 / 8521 CIA (×2) | Either NMOS or HMOS pair |
| U4 | 6567/6569 or 8562/8565 VIC-II | Auto-detects and sets clock |
| U5 / U6 | 6581 / 8580 SID (1 or 2) | Independent analogue rails |
⚡ Power & regulations
[edit | edit source]- Input: 12 V DC @ ≈1 A via 2.1 mm barrel jack (centre-positive).
- Rails generated:
+5 V (3 A) +9 V unregulated (SID 8580) +12 V (SID 6581) ~9 VAC square-wave for cassette motor & TOD clock.
The converters are >90 % efficient; board temperature stays below 35 °C in normal use – a marked improvement over the C64’s linear 7805/7812 regulators.
🎛️ Firmware / configuration
[edit | edit source]On first power-up the CPLD scans the sockets, identifies each chip revision and writes sane defaults to flash. Holding the MENU pushbutton during reset launches a ROM-resident setup program that lets the user:
- select PAL (50 Hz) / NTSC (60 Hz) / Turbo (2 MHz VIC-off) modes
- assign Kernal banks to the selector button
- map SID #2 to \$D420 (Stereo IN) or \$D500 (compatible with SID FX)
- adjust video phase to centre the image on HDMI up-scalers.
🛒 Availability & pricing
[edit | edit source]Two production runs have been sold exclusively through the Individual Computers web-store:
| Batch | Year | Units | Intro price (EUR) | Status |
|---|---|---|---|---|
| 1 | 2016 | ≈ 600 | €199.90 | Sold-out |
| 2 | 2018 | ≈ 800 | €214.90 | Sold-out |
A third run has been teased but no firm date announced (as of Q1 2025). Second-hand prices on auction sites routinely exceed €300, especially for boards that include rare 6581R4AR SIDs.
🔧 Known quirks
[edit | edit source]- Very early boards shipped with a SID audio balance offset; a CPLD firmware update (v0.9-RC4 or later) fixes the issue.
- The menu program requires a PS/2-level USB-TTL cable; generic 5 V serial adapters can harm the CPLD.
- PAL-E VIC-II 6569R1 chips are *not* supported due to their uncommon timing.
📚 Further reading
[edit | edit source]- Individual Computers – C64 Reloaded MK-II press release (2016)
- “Building my C64 Reloaded MK2” – *AmigaLove* forum photo-essay, 2018 -10-15
- GRay Defender, “Commodore 64 MK2 Reloaded” – YouTube build log, 2020 ©