The Brain Board with Wozanium Pack

The brain board is a firmware board for your Apple II/Apple II plus or Apple IIe computer. The board uses inexpensive and readily available 27c128 or 27c256 PROMs. Because of the denser PROMs used, 6 sockets are replaced with one and the resulting size of the board is reduced to under 3 by 4 inches. The original Apple firmware board was able to replace motherboard ROM functionality with it’s own ROM’s. This allowed an Apple II to have Applesoft in ROM or an Apple II plus to have Integer basic in ROM. A softswitch (flip-flop) is included which allows for switching between the firmware card and motherboard ROMs through software control. The board also includes a little known and seldom used capability that allows multiple firmware cards to coexist in the same system as long as they are in adjacent slots. Firmware cards were normally located in slot 0, but they could be located in any slot.

Later on in time, a 16K ram (language) card was developed that had the same functionality, except the appropriate BASIC was loaded into the language card from disk when DOS was booted. The multiple card support was dropped.

The base design of the Brain Board includes all the capability of the Applesoft/Integer Basic Firmware ROM board that Apple Computer released around 1978 including:

• a switch for enable/disable
• a software controlled switch (soft switch) for changing between motherboard ROMs
• firmware board ROMs jumper for enabling monitor ROM F8 - this was a solder pad jumper in the Apple design
• daisy chain enable functionality via DMA bus connections for multiple card support

In addition, ware added several enhancements in order to maximize usefulness of the board.

• The modified design will allow booting a ROM-less motherboard into DOS, which is not possible with the original firmware board 27C256 PROMs allow support of two complete ROM images on the Brain Board. Images of both Applesoft and Integer BASIC with matching monitors could be installed and used from the single PROM.
• An extra soft switch is used to select whether the high or low half of the PROM is in use. This soft switch can be configured by external switch, through software control or by jumper.
• The Apple II peripheral bus I/O select signal is connected to the lowest 256 bytes of the PROM bank that is currently selected by the bank select flip flop. I/O select is connected to a different address depending upon the slot the board is located in. Slot 0 does not have a I/O select signal, so this feature cannot be used if the Brain Board is installed in slot 0. The starting address for these 256 bytes is computed by multiplying 0x100 by the slot number and adding 0xC000. Thus slot 1 is 0xC100, slot 2 is 0xC200, etc.
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Project page : https://www.willegal.net/appleii/brainboard.htm

Author : Mike Willegal