This is a set of 4 PCBs for making your own cartridges for the IBM PCjr computer! Perfect for development, making reproductions or publishing your own game. The PCBs accepts a single 32K or 64K (E)EPROM and are configured using solder blobs. To use a 64K EPROM, a 74LS08 AND gate is also required.
The edge of the board with the contacts is beveled at a 30° for smooth insertion and the surface finish is ENIG (Immersion Gold).
While not as good as hard gold, it is arguably superior to the HASL (Hot Air Solder Leveling) finish IBM used on many cartridges...
Many similar PCBs use two 32K ROMs instead of a single 64K ROM as this one does. The rational behind this design choice
is that there are less pins to solder in total (saves assembly time) and the fact that a new 64K OTP EPROM actually cost less than
a pair of 32K EPROMs! Saving money and time is good right?
Tested chips include:
- Atmel AT27C512R (64K OTP EPROM)
- Atmel AT27C256R (32K OTP EPROM)
- Winbond W27E257-12 (32K EEPROM)
- ST M27C512 (64K UV-erasable EPROM)
- NM27C512 (64K UV-erasable EPROM)
Naturally, many other chips will work too! According to the PCjr technical reference manual, the access time must be of 250ns or less.
You will also need to make sure your EPROM programmer can program the chip you will use..
At the moment we only sell the PCBs. We do not provide EPROMs, capacitors or other chips.
Besides your own (E)EPROM chip, you will also need to provide:
- 0.1 µF Ceramic capacitors. Suggestion: AVX SR205C104KAR (Digikey 478-3187-ND)
- 10 µF Electrolytic capacitor. Suggestion: Nichicon UVR1C100MDD1TD (Digikey 493-12763-1-ND)
- 7408 AND Gate. Suggestion: Texas Instruments SN74ALS08N (Digikey 296-1484-5-ND) Only if a 64K ROM is used
- 28 PIN DIP IC Socket. Optional, for developement