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Created page with "{{Infobox computer | name = Ultimate 64 | image = 260px|frameless | caption = Ultimate 64 Rev-A production PCB with optional dual-SID sockets | developer = Gideon Zweijtzer (Ultimate Products B.V.) | manufacturer = Ultimate Products B.V.<br />assembled in the Netherlands | type = FPGA-based replacement motherboard for the Commodore 64 | release_date = December 2018 (public launch) | latest_release =..."
 
Infobox hardware per style guide; register availability corrected ( only with Turbo Enable Bit, /B write-only, separately enabled); Elite-II speed list adds 48 MHz; uncited FPGA-supply delay removed; self-reference removed; rechecked against Gideon's docs and the shop on 2026-10-01
 
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{{Infobox computer
{{Infobox hardware
| name          = Ultimate 64
| name          = Ultimate 64
| image        = [[File:Ultimate64-board.jpg|260px|frameless]]
| image        = [[File:Ultimate64-board.jpg|260px|frameless]]
| caption      = Ultimate 64 Rev-A production PCB with optional dual-SID sockets
| caption      = Ultimate 64 board, labelled V1.4
| developer    = Gideon Zweijtzer (Ultimate Products B.V.)
| type          = FPGA-based replacement motherboard
| manufacturer  = Ultimate Products B.V.<br />assembled in the Netherlands
| developer    = Gideon Zweijtzer
| type          = FPGA-based replacement motherboard for the Commodore 64
| manufacturer  = Ultimate Products (ultimate64.com)
| release_date  = December&nbsp;2018 (public launch)
| compatibility = Commodore 64
| latest_release = Firmware '''1.46c''' (May 2024)
| features      = HDMI 576p50 output, Ethernet, three USB 2.0 ports, two SID sockets, turbo mode to 48 MHz (64 MHz on the Elite-II)
| price        = €239 (base) / €269 (Elite, 2024 list)
| model        = Ultimate 64, Ultimate 64 Elite, Ultimate 64 Elite-II
| cpu          = cycle-exact 6510 core inside an Altera Cyclone-IV FPGA @ 48 MHz system clock (internally down-clocked to 0.98/1.02 MHz for C64 compatibility){index=0}
| memory        = 64 KB main RAM (emulated),<br />16 MB SDRAM for Ultimate functions
| storage      = Integrated '''1541-Ultimate II+''' functionality:<br />• dual SD/µSD card slots<br />• two USB 2.0 type-A hosts<br />• tape-read/write buffers
| display      = HDMI 720 p (50 Hz PAL / 60 Hz NTSC) with optional CRT-style scalers;<br />composite & S-video on DIN 8 AV port :contentReference[oaicite:1]{index=1}
| sound        = Two SID sockets (6581/8580/Swinsid/ARMSid) with automatic 9 V/12 V selection,<br />FPGA “Ulti-SID” emulation, 48 kHz 16-bit stereo over HDMI & USB-audio :contentReference[oaicite:2]{index=2}
| networking    = 100 Mbit/s Ethernet (RJ-45), optional Wi-Fi via USB
| dimensions    = 403 × 100 mm (matches C64C short-board standoffs)
| weight        = 410 g (populated, without case)
| os            = Commodore BASIC 2.0 ROM + Ultimate 64 menu firmware
| compatibility = Commodore 64, Commodore 128 (C64 mode), most cartridges & IEC drives
| predecessor  = [[1541 Ultimate II+]] (cartridge)
| model        = Ultimate 64, Ultimate 64 Elite
}}
}}
<templatestyles src="Template:StyledTable/styles.css" />


The '''Ultimate 64''' (commonly abbreviated '''U64''') is a modern, FPGA-based drop-in replacement for the Commodore 64 motherboard developed by Dutch engineer '''Gideon Zweijtzer''', creator of the 1541-Ultimate series.  Unlike software emulators, the U64 implements the complete C64 chipset (CPU, VIC-II, SID, CIAs, PLA, etc.) as gate-level clones inside a Cyclone-IV FPGA, delivering cycle-exact timing while adding contemporary amenities such as HDMI, Ethernet and solid-state mass-storage.
The '''Ultimate 64''' (U64) is a replacement motherboard for the Commodore 64 that implements the machine in an FPGA. It was developed by Gideon Zweijtzer, the designer of the 1541 Ultimate cartridges, and runs the same Ultimate firmware and menu as the Ultimate-II+ cartridge. The board keeps the original tape, cartridge, audio/video and serial ports and adds HDMI, Ethernet and USB.<ref name="doc">Gideon Zweijtzer, [https://1541u-documentation.readthedocs.io/en/latest/ ''1541 Ultimate-II(+) and Ultimate-64 Documentation''] (retrieved 2026-10-01): "Ultimate-64 Documentation" landing page; "HDMI port"; "Turbo mode settings"; "SID-TAP header"; "USB ports"; "Ethernet port"; "Firmware".</ref><ref name="shop">Ultimate Products, [https://ultimate64.com/ ultimate64.com] home page and [https://ultimate64.com/Ultimate64 "Ultimate 64 Main Boards"] (retrieved 2026-10-01).</ref>


== Key features ==
== Models and availability ==
* '''All-FPGA core''' – replaces every major MOS device, eliminating ageing silicon while preserving ~99.9 % software and demo compatibility, including tricky “cycle-tricks” and bad-line conditions.
On 1 October 2026 the ultimate64.com shop listed three Ultimate 64 items, all out of stock:<ref name="shop" />
* '''Integrated 1541-Ultimate II+''' – IEC drive emulation (D64/G64/TAP/T64/PRG), freezer, action-replay, REU (RAM Expansion Unit) up to 16 MB and GeoRAM, plus KERNAL cartridge injection and SID player.
* '''Digital video & audio''' – lag-free HDMI output at 720 p with optional scan-lines, border cropping and PAL/NTSC switching on-the-fly; 48 kHz 16-bit stereo mixes real SIDs with FPGA soft-SID.
* '''Dual-SID support''' – two physical sockets with automatic 9 V/12 V rail sensing; FPGA mixer allows true stereo separation and independent filter curves per chip.
* '''Network stack''' – 100 Mbit LAN for disk-image mounting over FTP/TFTP, firmware updates, IEC drive sharing and real-time clock synchronisation via NTP.
* '''Ultimate Command Interface''' – JSON‐RPC over USB or Ethernet for headless control and integration with PC front-ends.
* '''Silent & cool''' – the board draws ≈ 1.1 A @ 5 V; an optional 40 mm fan header is provided but rarely needed.


== Hardware overview ==
{| class="wikitable styled-table" style="width:70%; text-align:left;"
{| class="wikitable" style="text-align:center; width:90%;"
|+'''Ultimate 64 items on ultimate64.com, October 2026'''
! Component !! Implementation !! Notes
! Product !! Price
|-
|-
| CPU / PLA || Cyclone-IV EP4CE10F17C8N || 10 k LE FPGA (@ ~48 MHz master) :contentReference[oaicite:7]{index=7}
| Ultimate-64-Elite || €248.95
|-
|-
| RAM || 16 MB 166 MHz SDRAM || shared by REU, GeoRAM, freezer snapshots
| Ultimate 64 Elite-II || €248.99
|-
|-
| ROM || 2 × 1 Mbit SPI flash || holds multiple KERNALs & cartridge cores
| U64 UserPort Adapter, with 9 V AC || €9.98
|}
 
The shop's home page says the Elite-II "black short boards" are sold out and that Commodore has taken over sales of its own version of the board. It also notes that the shop is run by one person and usually ships once a week.<ref name="shop" />
 
== Video output ==
The HDMI output on the PAL version is 720 x 576 at 50 Hz (576p50), a standard CEA-861 mode with its timing slightly modified to match a C64. There is no frame buffer, so the board adds no frame delay; any lag comes from the display, and Gideon records one 4K screen that resampled the output to 30 Hz. When HDMI is in use, the C64 display connector is driven as well.<ref name="doc" />
 
== Turbo mode ==
The CPU and memory subsystem run at 48 MHz on the Ultimate 64 and 64 MHz on the Elite-II. The turbo setting does not change that clock; it sets how many of the available time slots go to the CPU, and the VIC still takes the cycles it needs.<ref name="doc" />
 
Selectable CPU speeds:<ref name="doc" />
* Ultimate 64: 1, 2, 3, 4, 5, 6, 8, 10, 12, 14, 16, 20, 24, 32, 40 and 48 MHz.
* Elite-II: 1, 2, 3, 4, 6, 8, 10, 12, 14, 16, 20, 24, 32, 40, 48 and 64 MHz.
 
Badline timing can be turned off to give the CPU more cycles, but the setting does not change the BA signal on the cartridge port. Accesses to the cartridge port, which always run at 1 MHz, still meet the badline limits, and so do accesses to the SID registers when the physical SID sockets are enabled.<ref name="doc" />
 
=== Turbo control registers ===
The registers are available only when the turbo mode selector in the menu allows them:<ref name="doc" />
 
{| class="wikitable styled-table" style="width:100%; text-align:left;"
|+'''Ultimate 64 turbo registers'''
! Address !! Function !! Available when
|-
|-
| Storage || µSD (front), SD (rear), 2×USB‐A || FAT32/exFAT up to 2 TB
| $D030 (53296) || Turbo Enable Bit. Write 0 for 1 MHz with badlines, 1 to use the menu settings. Read 0 = turbo off, 1 = turbo on. || Selector set to "Turbo Enable Bit"; otherwise reads $FF
|-
|-
| Video || ADV7125 DAC + HDMI transmitter || PAL/NTSC S-video & composite preserved
| $D031 (53297) || U64 Turbo Control. Bits 0-3 CPU speed index; bit 7 badline timing (0 enabled, 1 disabled). || Selector set to "U64 Turbo Registers" or "Turbo Enable Bit"; otherwise reads $FF
|-
|-
| Audio || TLV320AIC23B codec || 16-bit 48 kHz ADC for cassette in; DAC for soft-SID
| $D07A (53370) || SuperCPU-compatible software speed select, normal. Write only. || As $D031
|-
|-
| I/O || RTL8211E Gig-Ethernet PHY, FT232H USB FIFO || network & USB mass-storage/front-panel control
| $D07B (53371) || SuperCPU-compatible software speed select, turbo. Write only. || As $D031
|-
| $D0BC (53436) || SuperCPU mode detect. Read only. || When separately enabled
|}
|}
See also [[SuperCPU and Turbo Accelerators]].


== Models and revisions ==
== SID-TAP header ==
* '''Ultimate 64 (standard)''' – black PCB, single SID socket, no on-board RAM for cartridge emulation (relies on SDRAM).
An 8-pin header brings out the analogue signals of the installed SIDs before the board's own processing. A 3.5 mm jack can be wired to the SID OUT pins as a line out; the SID IN pins give a line in, which Gideon notes has not been functionally verified.<ref name="doc" />
* '''Ultimate 64 Elite''' – blue PCB, dual SID sockets, gold ENIG finish, additional fan header and improved audio output stage.
Both share the same FPGA bit-stream; differences are purely BOM-level.


== Firmware ==
{| class="wikitable styled-table" style="width:55%; text-align:center;"
Firmware images carry the prefix '''U64-<version>.bin''' and are flashed from the built-in Ultimate menu (F2) or via FTP.  Major branches:
|+'''SID-TAP header (top view; the arrow on the board points at pin 2)'''
 
! Function !! Pin !! Pin !! Function
{| class="wikitable" style="width:80%;"
|-
! Branch !! Highlights
| SID 2 OUT || 1 || 2 || Ground
|-
|-
| 1.4x (2022-) || HDMI low-lag scaler, new Soft-SID engine, EasyFlash 3 emulation, TC64-style turbo-CPU up to 48 MHz.
| Ground || 3 || 4 || SID 2 IN
|-
|-
| 1.3x (2020-2021) || REU page‐cross timing fixes, GeoRAM write-through, “Ulti-Pause” button mapping.
| Ground || 5 || 6 || SID 1 IN
|-
|-
| 1.2x (2019) || first public stable; added CRT composite sharpening and TAP write-back support.
| SID 1 OUT || 7 || 8 || Ground
|}
|}


== Compatibility ==
== USB and network ==
The board fits in any Commodore 64 “bread-bin” or C64C case; all original ports retain their position. Cartridge timing is cycle-accurate, so devices such as EasyFlash 3, Kung-Fu Flash, Tapecart, Ultimate II+ (cartridge), SuperCPU, REU 1764/1750, and RAMLink have been verified to boot.
There are three USB 2.0 ports, two at the back and one on the inner side of the board; USB 3 is not supported. USB 2.0 hubs work, and powered hubs are recommended; USB 1.1 hubs do not work. The Ethernet port shows as Net0 in the Ultimate menu, with a Network Settings menu for DHCP or a static address. It is not RR-Net compatible.<ref name="doc" />
Limitations:


* No analogue RF output (the TV modulator footprint is unused).
== Firmware ==
* Turbo-CPU modes (>1 MHz) break raster IRQ stable code and some fast-loader drive hand-shakes. 
The firmware and the FPGA core carry separate version numbers: firmware 3.10 shipped with core 1.41 and 3.10i with core 1.42. Firmware 3.15 added Ultimate 64-II hardware support, a machine-code monitor, a REST API, an FTP client and a renewed software IEC subsystem.<ref name="doc" />
* Cassette motor control is emulated; certain fast-loaders that sample the motor waveform may fail.


== Reception ==
== Not in the documentation ==
Hardware reviewers praised the '''crisp HDMI output''', silent operation and the convenience of having a full 1541-Ultimate inside the case. Some purists argue that FPGA SIDs—though vastly improved—still fall slightly short of certain analogue filter nuances of late-8580 silicon.
Gideon's documentation and the ultimate64.com shop do not give the FPGA part number, the RAM fitted, the board dimensions, the weight or the current draw. Read the markings on the board itself.


== See also ==
== Related pages ==
{{plainlist|
* [[C64 Reloaded MK2]]
* [[1541 Ultimate II+]]
* [[SuperCPU and Turbo Accelerators]]
* [[PLA Replacement Options]]
* [[PLA Replacement Options]]
* [[JiffyDOS Kernal Upgrade]]
* [[JiffyDOS Kernal Upgrade]]
}}
* [[Commodore 64]]
 
== References ==
<references />


[[Category:Commodore 64 Modifications and Enhancements]]
[[Category:Commodore 64 Modifications and Enhancements]]
[[Category:Commodore Systems]]
[[Category:Commodore Systems]]

Latest revision as of 14:33, 1 October 2026

Ultimate 64
Caption Ultimate 64 board, labelled V1.4
Type FPGA-based replacement motherboard
Designer Gideon Zweijtzer
Manufacturer Ultimate Products (ultimate64.com)
First released Unknown
Latest revision —
Operating voltage —
Layers / PCB —
Compatibility Commodore 64
Features HDMI 576p50 output, Ethernet, three USB 2.0 ports, two SID sockets, turbo mode to 48 MHz (64 MHz on the Elite-II)
Model No. Ultimate 64, Ultimate 64 Elite, Ultimate 64 Elite-II

The Ultimate 64 (U64) is a replacement motherboard for the Commodore 64 that implements the machine in an FPGA. It was developed by Gideon Zweijtzer, the designer of the 1541 Ultimate cartridges, and runs the same Ultimate firmware and menu as the Ultimate-II+ cartridge. The board keeps the original tape, cartridge, audio/video and serial ports and adds HDMI, Ethernet and USB.[1][2]

Models and availability

[edit | edit source]

On 1 October 2026 the ultimate64.com shop listed three Ultimate 64 items, all out of stock:[2]

Ultimate 64 items on ultimate64.com, October 2026
Product Price
Ultimate-64-Elite €248.95
Ultimate 64 Elite-II €248.99
U64 UserPort Adapter, with 9 V AC €9.98

The shop's home page says the Elite-II "black short boards" are sold out and that Commodore has taken over sales of its own version of the board. It also notes that the shop is run by one person and usually ships once a week.[2]

Video output

[edit | edit source]

The HDMI output on the PAL version is 720 x 576 at 50 Hz (576p50), a standard CEA-861 mode with its timing slightly modified to match a C64. There is no frame buffer, so the board adds no frame delay; any lag comes from the display, and Gideon records one 4K screen that resampled the output to 30 Hz. When HDMI is in use, the C64 display connector is driven as well.[1]

Turbo mode

[edit | edit source]

The CPU and memory subsystem run at 48 MHz on the Ultimate 64 and 64 MHz on the Elite-II. The turbo setting does not change that clock; it sets how many of the available time slots go to the CPU, and the VIC still takes the cycles it needs.[1]

Selectable CPU speeds:[1]

  • Ultimate 64: 1, 2, 3, 4, 5, 6, 8, 10, 12, 14, 16, 20, 24, 32, 40 and 48 MHz.
  • Elite-II: 1, 2, 3, 4, 6, 8, 10, 12, 14, 16, 20, 24, 32, 40, 48 and 64 MHz.

Badline timing can be turned off to give the CPU more cycles, but the setting does not change the BA signal on the cartridge port. Accesses to the cartridge port, which always run at 1 MHz, still meet the badline limits, and so do accesses to the SID registers when the physical SID sockets are enabled.[1]

Turbo control registers

[edit | edit source]

The registers are available only when the turbo mode selector in the menu allows them:[1]

Ultimate 64 turbo registers
Address Function Available when
$D030 (53296) Turbo Enable Bit. Write 0 for 1 MHz with badlines, 1 to use the menu settings. Read 0 = turbo off, 1 = turbo on. Selector set to "Turbo Enable Bit"; otherwise reads $FF
$D031 (53297) U64 Turbo Control. Bits 0-3 CPU speed index; bit 7 badline timing (0 enabled, 1 disabled). Selector set to "U64 Turbo Registers" or "Turbo Enable Bit"; otherwise reads $FF
$D07A (53370) SuperCPU-compatible software speed select, normal. Write only. As $D031
$D07B (53371) SuperCPU-compatible software speed select, turbo. Write only. As $D031
$D0BC (53436) SuperCPU mode detect. Read only. When separately enabled

See also SuperCPU and Turbo Accelerators.

SID-TAP header

[edit | edit source]

An 8-pin header brings out the analogue signals of the installed SIDs before the board's own processing. A 3.5 mm jack can be wired to the SID OUT pins as a line out; the SID IN pins give a line in, which Gideon notes has not been functionally verified.[1]

SID-TAP header (top view; the arrow on the board points at pin 2)
Function Pin Pin Function
SID 2 OUT 1 2 Ground
Ground 3 4 SID 2 IN
Ground 5 6 SID 1 IN
SID 1 OUT 7 8 Ground

USB and network

[edit | edit source]

There are three USB 2.0 ports, two at the back and one on the inner side of the board; USB 3 is not supported. USB 2.0 hubs work, and powered hubs are recommended; USB 1.1 hubs do not work. The Ethernet port shows as Net0 in the Ultimate menu, with a Network Settings menu for DHCP or a static address. It is not RR-Net compatible.[1]

Firmware

[edit | edit source]

The firmware and the FPGA core carry separate version numbers: firmware 3.10 shipped with core 1.41 and 3.10i with core 1.42. Firmware 3.15 added Ultimate 64-II hardware support, a machine-code monitor, a REST API, an FTP client and a renewed software IEC subsystem.[1]

Not in the documentation

[edit | edit source]

Gideon's documentation and the ultimate64.com shop do not give the FPGA part number, the RAM fitted, the board dimensions, the weight or the current draw. Read the markings on the board itself.

[edit | edit source]

References

[edit | edit source]
  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 Gideon Zweijtzer, 1541 Ultimate-II(+) and Ultimate-64 Documentation (retrieved 2026-10-01): "Ultimate-64 Documentation" landing page; "HDMI port"; "Turbo mode settings"; "SID-TAP header"; "USB ports"; "Ethernet port"; "Firmware".
  2. ↑ 2.0 2.1 2.2 Ultimate Products, ultimate64.com home page and "Ultimate 64 Main Boards" (retrieved 2026-10-01).
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