Tag: internal mod

Adds a battery-backed real-time clock to Atari XL and XE computers as an internal module, pass-through cartridge, or circuit inside another cartridge.

The project page publishes a parts list, clock and address-decoder schematics, battery and rechargeable-cell backup circuits, and an ARC handler archive. It recommends internal installation because the pass-through and inside-another-cartridge forms may cause more problems. The page does not provide a step-by-step bus-wiring guide: an internal build must source D0-D3, A0-A7, R/W, phase 2, power, and D5xx cartridge-control signals, while a cartridge build uses the cartridge connector. No explicit project license or current assembled seller was verified.

Adds 1 MB of banked RAM to an Atari 1200XL or 800XL with a 30-pin SIMM and custom refresh and bank-selection logic.

The archived article provides the circuit discussion, 1200XL connection table, SIMM pinout, and software notes but describes the 800XL only as having similar connection points. It is an advanced historical wire-and-perfboard build. The author reports that the SpartaDOS cartridge does not function with this configuration and that ordinary SpartaDOS and much commercial software see only a 320XE-style subset; MYDOS 4.5.1M or newer needs the documented page sequence.

Open, through-hole RF-modulator replacement with adjustable C64 luma and chroma output levels.

The repository supplies KiCad sources, Gerbers, a schematic, a BOM, and assembly and adjustment instructions. Components were estimated at about $12 when documented, excluding PCBs and shipping. Building the board requires through-hole assembly; installing it requires safely desoldering the original RF can and selecting the correct jumper configuration. Using the shortboard setting on a longboard can feed the wrong voltage and damage the VIC-II.

Open RF-modulator replacement that improves the C64's original luma, chroma, and composite video signals.

Retro Electronics listed one board in stock on 2026-07-25. Installation is an irreversible soldering job that removes the original RF modulator, adds two headers, and solders a ground wire.

Expands a 16 KB Atari 600XL to 64 KB with two 41464 DRAMs and three wiring changes.

The archived instructions call for two 41464-10 or compatible DRAMs, hookup wire, soldering tools, and optional sockets. Chips may need desoldering, several pins and resistor leads must be isolated, and fine motherboard traces are exposed; the author explicitly says to attempt it only if the diagram is understood and at the builder's risk. This is a historical modification guide, not a current kit.

Replaces a C64 RF modulator with FPGA-generated 1080p HDMI video and digitized stereo audio while retaining analog video.

Authorized seller Retro-Updates listed hardware version 0.2 at EUR 109.00 on 2026-07-27. Confirm the exact revision and production batch before ordering: the manual documents incorrect chroma resistors in the first version 0.2 production batch, an ineffective PLL-adjustment jumper on batches 1 and 2, and a transmitter issue that prevents HDMI audio on a small minority of displays.

Replaces the power light with a two-color indicator that shows the computer's IRQ-line state.

Shareware Plus said the C64 breadbin, C64C slimline, and VIC-20 versions were in stock at GBP 9 each plus postage on 2026-01-25 and accepts email orders. The tebl C64 design is buildable under CERN OHL v1.2. This is an IRQ-line indicator, not a complete CPU-usage or disk-activity meter. Installation opens the computer and places clips on cartridge-port ground, +5 V, and IRQ contacts; verify every connection with power off.

Sharpens video on some PAL or NTSC Atari 600XL and 800XL boards by disconnecting one filter capacitor.

The recovered 2017 discussion says to lift or cut one capacitor leg, making later restoration possible, and the author tested PAL and NTSC machines only. SECAM compatibility is unresolved. Several commenters report that later Revision D 800XL boards omit C56 or use a different layout, so identify the exact board revision and component before changing anything. The quoted 80 percent improvement is the author's subjective estimate, not a measured specification; more complete video upgrades may produce better output.

Open internal video-overlay module that displays expansion status and other configured messages over C64 composite or S-Video output.

The maker offered assembly kits by email for 25 EUR including regular worldwide mail on 2026-07-30, with a limit of two per person. Stock is kept when practical, but prepaid production batches can take several weeks. The kit includes the PCB, a preprogrammed ATmega, and board components, but not the computer-specific wiring. C64 installation is an advanced internal modification: use amplified luma from A/V pin 1 for S-Video or composite from pin 4, never the unamplified VIC-II luma signal. Driving both outputs requires an expert RF-modulator connection, and excessive overlay brightness can disrupt sync.

Uses a 1 MB 30-pin SIMM and GAL controller to add switchable Compy Shop or Newell/RAMBO banked memory to Atari XL and XE computers.

The Polish project page publishes a schematic, GAL JEDEC file, utilities, parts list, full 800XL and Freddie-equipped 800XLF instructions, startup tests, and timing troubleshooting. Installation is highly invasive and may require trace cuts, lifted or bent IC pins, motherboard timing changes, and RAS-delay tuning for a particular machine. The page groups the 600XL and 1200XL with older 800XL memory-control hardware but does not provide separate step-by-step guides for those models. No explicit project license was verified.

Replaces the RF modulator in supported C64 and C128 systems to improve composite and S-Video output and add configurable rear connections.

The Lectronz page showed four units in stock at USD 34.17 on 2026-07-27. Machine-specific versions and optional luma-bypass parts are selected before ordering. The seller also reported that shipping to the European Union was temporarily unavailable while Australia Post updated its duty systems.

Replaces the C64 RF modulator with composite, optional S-Video, and mono or dual-SID audio connections.

The official store listed RFOUT! at 22 EUR but out of stock on 2026-07-30. It provides a composite socket, a 3.5 mm audio jack, and solder points for an optional S-Video connector; stereo output requires a dual-SID source and the SJ1 setting. Installation requires desoldering the original modulator. Measure the motherboard supply before installation: boards carrying 12 VDC or 9 VAC on pin 1 require that pin to be removed and a separate 5 VDC connection supplied to RFOUT!. Confirm the footprint, voltage, extension-board fit, and case height before soldering.

Replaces the C64 RF-modulator circuitry while retaining composite and S-Video through the computer's A/V port.

The current maker page remains online but exposes no price, stock state, or order control. Human inspection recovered a maker compatibility list naming PAL and NTSC Assy 250407 C64 boards and all C128 board revisions; Tavily did not render those list values. A 2020 independent review also tested a SixtyClone Assy 250466, where both composite and S-Video worked. Removing the original modulator and installing Shuriken requires desoldering and soldering. RF output is removed.

Replaces the 4050 video buffer and routes configurable conditioned video signals to the Atari's output connector.

The product exposed a login-or-register-to-buy path on 2026-07-27. Installation replaces the 4050, connects GTIA pin 21 to the board's color input, and rewires output signals at the computer's video connector. A non-socketed 4050 and the output modification require desoldering and model-specific board work.

Discontinued C64C RF-modulator replacement with rear-panel S-Video and 3.5 mm audio jacks.

The original maker site is gone, and a 2020 discussion describes the closed design as dead. An independent review tested an older version on an Assy 250469 Rev. 4 C64C: the first board was faulty, the replacement worked, CRT S-Video improved slightly, flat-panel results were worse, and composite output was unusable in that setup. A later eBay version once claimed C64C and C128D support plus an AEC fix, but no surviving manual or seller page establishes its exact differences or safe C128 installation. Buy used only with a return option and exact revision documentation.

Adds an internal SwiftLink-compatible ESP8266 Wi-Fi modem to the flat-model Commodore 128 while leaving its cartridge port available.

The assembled Tindie listing was retired by 2026-07-30, while the open project retains hardware and firmware material. The archived Tindie instructions specify socket U4, but the maker's merged README says U2, and human review found no surviving material that resolves the conflict. Do not install from the catalog summary; inspect the project files and verify the correct CIA socket against the exact board.

Adds an internal SwiftLink-compatible ESP8266 Wi-Fi modem to supported Commodore 64 longboards and Commodore 128DCR systems.

The assembled Tindie listing was retired by 2026-07-30. The open project retains Eagle design files, firmware, patches, and installation material. This is a board-specific internal installation that requires removing and reusing a 6526 CIA plus routing flying leads; verify the motherboard revision and instructions before fitting it.

Publishes an experimental 1024 KB plus 64 KB SRAM expansion board for the Atari 600XL and 800XL.

The author labels the April 2025 post UNDER WORK and calls it a placeholder. A KiCad archive containing the stated schematic and Gerbers is downloadable, but the page provides no bill of materials, assembly guide, firmware, electrical test results, completed installation report, or explicit license. Treat it as an unfinished engineering project for experienced builders, not a validated kit.

Adds NTSC composite video to tested RF-only vintage computers with a small internal solder-in board.

The JCM page offered kit and assembled two-packs with an Add to Cart path on 2026-07-24. Documentation is for North American NTSC hardware. The 600XL procedure cuts one side of the RF-output resistor and can restore RF only by resoldering it; the installer must verify all connections against the host schematic.

Adds clean composite and S-Video output circuitry to supported Atari 8-bit computers.

The Atari 8-bit Rev. D page said Now shipping on 2026-07-24 and offered plug-in, basic, kit, and 1088 variants. Installation still requires soldering, output jacks, and the ability to follow a schematic. The vendor calls its large manual a starting collection and warns that not every machine has explicit or fully current instructions. The separate 600XL monitor port and BOBby audio/video breakout are installation accessories, not standalone upgrades.

Open internal C64 modification that switches between installed PAL and NTSC VIC-II chips and includes LumaFix64 video cleanup.

The current project page provides build files, component links, PCB ordering routes, and a video guide under CC BY-NC-SA 4.0. This is not a plug-and-play board: installation removes the RF shielding, desolders motherboard parts and jumpers, adds pins, and requires both a 6567 and 6569 VIC-II. The connected display must accept both PAL and NTSC or one switch position may produce monochrome video or no usable picture. The authors provide no warranty or installation support.

Documents period DIY memory conversions that give an Atari 400 48 KB plus a banked 16 KB or an Atari 800 a 288 KB SuperRam configuration.

These are historical, invasive board-level modifications rather than current kits. Both require extensive disassembly, trace cuts, soldering, stacked or perfboard logic, and staged electrical testing. The authors release the instructions for public use with attribution. The Atari 800 text lists six 41256 DRAMs, while human review found only one 41256 in its rough circuit sketch. The contradiction remains unresolved: do not treat the Atari 800 parts list or sketch as an authoritative build package without reconstructing and checking the circuit.