Tag: 781220

2 matching upgrades

Showing 2 products.

StatusProductWhat it doesCompatibilityLinks
AvailableChecked Jul 30, 2026C64 781220 Dead Test Cartridgeby Commodore service ROM; current build by Retro Rewind
c64c64csx 64c128781220dead testdiagnostic cartridgeram testrom testrepair

Boots before the normal KERNAL to diagnose RAM and ROM faults on a Commodore 64 that cannot reach its startup screen.

Retro Rewind listed its cartridge in stock at CAD 22 on 2026-07-30. TFW8b documented a compatible alternative for C64, C64C, SX-64, and C128 in 64 mode, but that listing was out of stock. Wait up to 60 seconds for a result. The original 781220 RAM routine covers only the lowest 4 KB, and the cartridge does not test the chips and I/O covered by a harness kit.

Sources
  • Commodore 64 Exact model
  • Commodore SX-64 Exact model
  • Commodore 128 Exact model
Buy the Retro Rewind Dead Test cartridge781220 service ROM, manual, and disassemblyTFW8b cartridge listing
AvailableChecked Jul 30, 2026C64/C128 Diagnostic Cartridge Familyby Commodore service ROMs, Sven Petersen open hardware, and multiple current assemblers
c64c64csx 64c128781220586220785260dead testdiagnostic cartridgemulti rom1541burn in testsid testport testopen hardwarerepair

Packages 586220, 785260, and related service ROMs as current single-ROM and switchable multi-ROM diagnostic cartridges.

Current choices on 2026-07-30 included Retro Rewind's in-stock CAD 22 C64 586220++ and C128 785260 cartridges, its CAD 40 four-ROM C64 cartridge with a two- to three-day lead time, AMI64's GBP 19 eight-ROM C64 cartridge with an approximately seven-day lead time, ogHugo's USD 26.99 before-tax two-sided C64 cartridge with an Add to Cart path, Retro-Updates' EUR 17.99 two-sided C64 cartridge, and C64iSTANBUL's orderable two-ROM PCB with current fabrication files. DIY8BIT's USD 22.95 781220/586220 cartridge was unavailable while its Etsy shop was on break. Retro Rewind's older Dual Diag route now displays the store's not-found page. ROM sets and model support differ by variant; a full port test requires a separately bought or built harness.

Sources
  • Commodore 64 Exact model
  • Commodore SX-64 Exact model
  • Commodore 128 Exact model
Diag64cart open projectMulti-cartridge design and ROM notesBuy the Retro Rewind C64 586220++ cartridgeBuy the Retro Rewind C128 785260 cartridgeBuy the Retro Rewind four-ROM cartridgeBuy the AMI64 eight-ROM cartridgeBuy the ogHugo two-sided cartridgeBuy the Retro-Updates two-sided cartridgeOrder the C64iSTANBUL two-ROM PCBWatch the DIY8BIT two-ROM listing