Adding Flash Memory

9 May

Adding 512 kbytes Flash Memory
The TINI stick has 512 kbytes of flash EEPROM that is used for storing the Java Virtual Machine and Slush. TINI uses an Advanced Micro Devices AM29F040B4 512-kbyte flash EEPROM. If you examine the memory map again, you will see that TINI can address 1 Mbyte of flash EEPROM. If you are using the E10/E20 socket board or you have constructed your own, you can add flash off stick. One of the biggest advantages of using a second flash chip is to allow for an alternate operating system. Notice in the section of the TINI socket board schematic shown below that the flash memory control logic is configured so that either the on-stick or the off-stick flash can be addressed first. If you change these solder-jumpers to a switch, you now have switch-selectable boot control. Notice that the flash EEPROM on the TINI stick is enabled with the /XCE0 line and the flash EEPROM on the TINI socketboard is enabled with the /RCE0.

If your socket board does not have provision for a second flash chip, then the /CE0 line is routed back onto the TINI stick as /XCE0. If you do have provision for a second flash then these two lines are controlled by the flash control with solder jumpers. These jumpers either bypass the flash control directly when J27 is shorted or determine which of the two flash chips is first addressed (/XCE0). The on-stick flash is first when J13 and J16 are shorted (as a pair) and the off-stick flash is first when J14 and J15 are shorted. Note that an unpopulated E10/E20 socketboard uses another solder jumper (J27) to bypass the flash control altogether.

Figure 8-3: Flash memory control
If you solder on the components for the flash control, then you can change these solder jumpers to select which flash your TINI uses to boot from. You can replace these solder jumpers with switches so you can select which flash ROM is the boot flash quicker then messing with solder jumpers.

Adding a SIMM Connector
The current TINI stick is based on the common 72-pin SIMM (single inline memory module) standard. An early version of the TINI was based on a 68-pin SIMM but this was changed to take advantage of the more common 72-pin connectors that are popular for personal computer memory modules. The 72-pin SIMM socket is available in many configurations, depending on how you need to mount your TINI (for mounting the TINI stick perpendicular or parallel to the socket board). The TINI stick form factor conforms to the JEDEC JEP95 MO-1165 standard specification, more or less. The TINI SIMM fits in a standard 72-pin SIM socket, including the key (the notch near pin 1) but the overall card height seems to be nonstandard. Molex6 makes a number of 72-pin SIMM connectors as shown in Table 8-2.

Table 8-2: SIMM styles

The E10/E20 sockets support a second SIMM connector for expansion boards. Adding a second SIMM connector is almost as simple as unclogging the soldered through-holes on the socket board and soldering in a second connector.

So, what to do with a second SIMM socket? There are two current expansion boards on the market at the moment:

• SIMMSerial – The Systronix SIMMSerial7 is a TINI-pinout compatible, 72- pin SIMM module with dual hardware UARTS (16C552) compatible with the current TINI firmware. Each RS232 can be wired as DCE or DTE. One RS232 can be used as IrDA. The module works with any TINI system with an available SIMM72 socket.

• protoModule – The TINI protoModule8 allows for further expansion of the TINI stick. The board is simply a 0.1″ center grid of through holes on a 72-pin SIMM. This allows a developer to design a variety of circuitry on one or more protoModules and then plug them into a TINI socketboard equipped with a 72-pin SIMM connector for test and debug. ProtoModules can be used with a variety of boards such as the Dallas Semiconductor E10/E20, the Systronix STEP board and the Vinculum NEXUS board.

Figure 8-6: SIMM pinout

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