5 pcs 2364 or 2332 ROM replacement adapter - bare PCBs only

Many classic computers use 2364 or 2332 mask ROMs. No direct replacements are being manufactured to day and as a result the retro computer community has developed modern replacements. This adapter is a take on such an adapter and is based on the 28C64 / 28C256 EEPROM in PLCC form factor. The PLCC form factor allows the EEPROM to be socketed and therefore EEPROM is removable by the end user and can be easily reprogrammed by the end user with just about any EPROM programmer, including the very popular TL866. The PLCC form factor also allows through hole parts, while the adapter remains limited in size in both surface as height. The 28Cxxx EEPROMs are still being manufactured today, so availability is no problem.

The item sold here is just the bare PCB only: You will need to add pin headers, a PLCC socket and an EEPROM yourself. All parts are through-hole components, so it is easy to solder, even if you are a novice solderer. The adapter also comes with an instruction manual.

2364 mask ROMs have been used in at least the following computers:

• Commodore VIC-20 (KERNAL and BASIC ROM)
• Commodore 64, long boards (KERNAL and BASIC ROM)
• Commodore 128 (character ROM)
• Commodore 1541 floppy drive (DOS low and high ROM)
• Acorn Atom
• Atari 800XL
• Atari 1050 floppy drive
• IBM PC 5150 (U28/U29/U30/U31/U32/U33)
• Sinclair ZX81
• Tandy TRS-80

2332 mask ROMs have been used at least in the following computers:

• Commodore VIC-20 (character ROM)
• Commodore 64 (character ROM)
• Commodore PET
• Commodore CBM 4000/800 line
• Sinclair ZX80
• Synertek SYM-1
• Tandy TRS-80
• Texas Instruments TI99/4A

2364 ROMs have been manufactured by various manufacturers. ICs may have the following labels: 2564, 2664N, 27HC641, 9464B, 9464C, AM9264, CY7C264, G2364, M2364, MCM68764, MK36000, MM52164, MPS2364, MSM2965, NCR2364, R09464C, R2364A, R2912, S68B364, SY2364, TMM2366P, TMS4764, UM2364, UPD2364. If an IC is labeled with one of these, you can use this adapter to create a replacement.

The adapter is ideal as a spare part for situations where your old computer has a broken ROM. It is also usefull if you want to run custom ROMs, for example if you want to install JiffyDOS in your Commodore 64. Because the EEPROM can be removed and reprogrammed by the end user, you can easily reflash your old computer when you like.

If used in combination with a 28C256 EEPROM, you can use this adapter also as a ROM switcher. The adapter has soldering points available for connecting switches.

The adapter can be used as is as a replacement for 2364 mask ROMs. For 2332 ROMs, some reconfiguration might be required in order to correctly route the CS2 line (which is by default connected to A12 just like the 2364). The adapter can be used as is to replace the 2332 character ROM in the Commodore 64. The instruction manual explains how to properly configure the adapter for 2332 applications where reconfiguration is required.

You will receive:

• 5 * adapter PCB
• 1 * Instruction manual

 Parts that you need to source yourself to build a single adapter:

• 28C64 or 28C256 EEPROM
• 32 pin PLCC through-hole socket
• 2 * 12 pin header

Do you prefer a kit with all required parts? Look here.
Do you prefer a preassembled adapter that is ready to plug-in? Look here.