Using multiple eeprom chips for program storage, with BS2 OEM ?

CuriousOne

Hello. Is such thing possible? I want to make one board with bs2 oem, but add several eeprom chips, so I can run several large programs from separate chips when needed. I think of adding some rotary switch or multiplexer chip, to select proper eeprom when needed. Will this work?

Mike Green

If you keep the leads short (to minimize the capacitance), you should be able to switch between several EEPROM chips manually. It would be much easier to just use a Stamp model with multiple "slots" of EEPROM like the BS2p/pe/px. Typically, the main slot has a master program which, in addition to providing some common program, selects one of 7 other programs to execute. The Stamp Manual goes into details of this and there's a Nuts and Volts Column on multi-slot programming. The BS2pe also has 8 2K "slots" of EEPROM for use for data storage (not programs).

CuriousOne

I want to make some sort of "cartridges", so user can swap or add new ones, for better functionality, so if I understand properly, regular DIP socket and chip might not work due to wiring problems?

PJAllen

They're I2C devices.
You could have multiple devices on the clock and data lines.
All you would have to do is add a DIPswitch to enable (A0,A1,A2 low) the desired device via the Address lines.

Duane Degn

You might want to take a look at how the Hydra (Propeller Game System) dealt with external EEPROM. It used some sort of trick so it accessed the EEPROM on a card when it was inserted but when no card was present it used the normal EEPROM on the board. I don't recall the details but I do remember thinking it was a cool trick. I think the technique could be adapted for use with a BS2 (if you wanted one EEPROM always attached).

OT: I purchased the Hydra (on sale) because the manual was sold out and the only way to get the manual was by purchasing the full system. Now the manual is available as a free download. Lot's of great stuff in the manual (mostly Propeller specific).