Commodore 1526/MPS-802 Graphics EPROM Upgrade – M2764A ROM Chip
Commodore 1526/MPS-802 Graphics EPROM Upgrade – M2764A ROM Chip
A replacement EPROM that adds graphics-printing support to the Commodore 1526 and MPS-802 dot-matrix printers—burned with the mps802_switchable_gfx ROM set. Lets you print from titles like The Print Shop.
What you get One (1) M2764A EPROM, programmed and verified — plus a section of the actual self-test printout from when this specific chip was installed and tested in a working MPS-802 here at the workshop. Each chip is tracked by number; your printout matches your chip.
What the upgrade actually adds The mps802_switchable_gfx ROM set is the community dump of the original German "Grafik ROM II"—a 1980s commercial firmware upgrade for the MPS-802 / 1526. Once installed, the printer gains support for 19 MPS-801 emulation commands and 3 ESC/P commands for graphic printing, which is what lets era-typical Commodore software (The Print Shop and similar titles) actually drive the printer for graphics output. The chip itself is the same M2764A you'd burn at home—pre-programmed and verified at the CRT workshop.
Compatibility Fits the Commodore 1526 and MPS-802 printers (functionally identical units under two badges). Replaces the original ROM at position U8 on the printer's main PCB.
Installation note This is not a drop-in chip swap. You'll need to desolder the original ROM and re-position two jumpers (J1 / J2 / J3 / J4) on the board. The new chip itself sits in a socket—no chip-level soldering. If you're not comfortable with basic through-hole desoldering on 40-year-old hardware, this isn't the upgrade for you.
Credit and history The original "Grafik ROM II" was a commercial 1980s German upgrade for the MPS-802; the actual ROM authors are an unknown German vendor of that era. The reason this chip exists in 2026 is the work of Lemon64 user marcelv, who dumped the EPROM from a working unit, translated the install procedure from the original German paper manual, and openly shared both back in 2011. The community archive moved around over the years and the ROM file has gotten increasingly hard to find online—the original cbm8bit.com host went down, and a 2023 thread on Lemon64 has another user struggling to locate it. I'm burning marcelv's dump onto fresh chips so anyone with an MPS-802 or 1526 can install the upgrade without having to track down the firmware file themselves.
Original Lemon64 thread (worth reading if you want the full community history): https://www.lemon64.com/forum/viewtopic.php?t=36718
The backstory I picked up a Commodore 1526 printer and was disappointed by its lack of graphics support. A little searching found marcelv's thread on Lemon64—he had identified the swap-and-jumpers procedure and shared it openly. I followed his steps, and now print happily from The Print Shop. This product is the same modification, ready to install.
Installation (from marcelv's documentation)
- Open the printer (4 screws on the bottom), remove the print ribbon and knob, lift the upper case.
- Remove the PCB cover (2 screws).
- Locate U8, next to the 6504 CPU. Remove the existing ROM. If it's a mask ROM (not an EPROM), change the jumpers on the board.
- Install the new M2764A EPROM at U8.
- Set jumpers: J3 and J4 closed, J1 and J2 open.
Important: These printers are 40+ years old. Work patiently, use proper desoldering technique, and don't rush.
Built, bench-tested, AND printer-tested before shipping. Every chip goes through a four-step workflow at the CRT workshop: programmed on the EMP-20 with a full burn cycle, content-verified at the 5.00V operating voltage, read back to disk and binary-compared (DOS fc /b) against marcelv's source file, and then installed in a working MPS-802 to run the printer's built-in self-test on real hardware. Each chip is labeled with a unique tracking number, and a section of that specific chip's self-test printout ships in the same envelope. Physical evidence that the unit you're installing has already printed once on a working MPS-802. If anyone ever questions whether the chip works — including you, six months later — you have the receipt.