New member. New (to me) Apple II plus with interesting card

Pics of the card front and back would be a great start.

I've never seen one of those.  It looks like a 16k RAM card (language card replacement) plus a Real Time Clock and a Parallel printer port multifunction card.  Pretty cool.  Not sure how you address the clock or parallel port given most software for that usually is designed for cards that live in other slots cards intended for slot 0 normally don't use geographic I/O addresses or ROM space, and clock and printer cards usually do both.  I would guess the software for that card runs from main memory.

PeterKerr wrote:

Good point. Card was inserted in the slot closest to the powersupply. Based on the instructions from the linked doc, you move a ram chip from the Apple II board to the card and plug the pigtail into the empty socket.

Bus connections on front:

• 1 : IOSEL not connected, card does not have any ROM firmware, typical configuration for a slot 0 card
• 2-5 : A0-A3 address pins connected, typical configuration for cards with 16 IO ports accessed by DEV
• 6-13 : A4-A11 address pins  not connected, address bus not used to address onboard RAM. (card must use mux'd addresses through the pigtail)
• 14-17 : A2-A15 address pins connected, address bus is being used to select onboard RAM (when enabled)
• 18 : R/W distinguishes between read operations and write operations
• 23-24 : DMA OUT / INT OUT daisy chain passes through two vias, not connected to the circuit, card does not participate in DMA chain
• 25 : +5C positive power supply

Bus connections on rear:

• 26 : GND 0-volt power supply
• 27-28 : DMA IN / INT IN daisy chain passes through two vias, as described at 23-24 above
• 30 : IRQ interrupt signal, possibly connected to 6522 VIA
• 31 : RESET signal
• 32 : INH enables onboard RAM to override motherboard ROM addresses, typical configuration for slot 0 card
• 34 : -5C negative 5-volt power supply
• 36 : 7M clock
• 38 : phase-1 clock
• 40 : phase-0 clock
• 41 : DEV device select for IO ports
• 42-49 : D0-D7 data pins for entire data bus
• 50 : +12C positive power supply

Yuck.  It will function as an ordinary slot-0 RAM card, but beyond that it's just too clever by half...resulting in a design that's so kludged to work around all the impairments of slot 0 that it essentially offers none of the benefits of all its extra features.

• 16K RAM Card - like the Language Card.  Assuming this feature is backward-compatible with ordinary slot 0 RAM cards, it would consume at least 8 of the 16 available DEV ports.
• Bidirectional parallel port - port B of the 6522 VIA.  Ordinarily a 6522 would consume 16 IO ports, but half of the DEV ports would have been consumed by the switches needed for the 16K RAM so it's not clear how the additional ports have been hacked to make it accessible.  Software or firmware must configure the VIA before the parallel port will work, so this card's parallel port is incompatible with programs that perform direct parallel IO.  But the card doesn't have any ROM, so this card's parallel port is also incompatible with programs that perform firmware-based IO.
• Clock functions - probably port A of the 6522 VIA, since port B is used for the parallel port and its associated handshaking.