Ginger

Ginger

Summary

Ginger is an integrated Socket Shift, 2x CPU switch, and 4x Clock Port & RTC expansion, for use with the A500+ mITX ("Denise") board by Enterlogic.

Features

Socket Shift

Enables simultaneous use of accelerator boards and the Denise CF-Floppy I/O PCB.

The socket shift is designed primarily to accomodate Matthias Heinrichs' accelerators 68EC020-TK (in CPU1 socket) or 68030-TK2 (in CPU2 socket), although others will probably work as long as they are not unreasonably large.

CPU switch

Keep both your accelerator and OG 68000 CPU available easily with the flick of a switch!

DMA enable

This allows the 68000 CPU, when enabled, to make use of DMA resources - like an IDE controller - that reside on the accelerator board.

This feature is tested with recent firmwares of the 68EC020-TK and 68030-TK2 by Matthias Heinrichs.

It might not work with other accelerator boards. The function is accomplished by connecting the RESET signal of the active CPU to the (otherwise inactive) accelerator board instead of constantly holding the accelerator's RESET line low all the time.

Clock Port / RTC Expansion

Four clock ports (in the sense of Gayle's "SPARE" mapping) and one RTC port (for actual clock use) are made available on the 30-pin FPC connector.

Usage

Installation height

In order to plug in the Ginger into the Denise's CPU socket the pins should have a length of about 8.5mm between the Ginger PCB and the Denise's CPU socket. Otherwise the Ginger or any plugged-in accelerators will collide with other parts on the Denise board.

A viable part is Mill-Max 342-10-164-00-592000 which can be cut in half to yield two rows of 32 pins each.

Alternatively it is possible to stack multiple DIP64 sockets to reach the desired height.

Connections

30-lead FPC connector - Clock Ports

Four buffered clock ports (with a single shared RTC mapping) are available on the 30-lead FPC connector.

The four clock ports (represented by the /SPAREn_CS signals) are mapped as follows:

• SPARE0: $D80001
• SPARE1: $D84001
• SPARE2: $D88001
• SPARE3: $D8C001

Adapter PCBs with actual clock port pin headers are available:

• "Daisy": Single clock port
• "Clover": Four clock ports

Repository: ClockPort-FPC-Adapters

The Adapter PCBs have non-mirrored pinouts on their respective FPC connectors, so a "B-Type" FPC cable has to be used, where the contact surfaces at the ends are on opposite sides (top ↔ bottom).

The FPC pinout is as follows:

---

/INT6 Pin

An additional /INT6 pin is present next to the FPC connector. This pin must be connected to the /INT6 signal on the Amiga's main board e.g. using a jumper wire since it is not available on the CPU socket.

The Denise provides a pin header containing the signal.

Jumpers

DMA_EN

• Closed: RESET signal from the active CPU socket is propagated to the inactive CPU socket. Enables usage of the inactive CPU socket's peripherals on some accelerator boards.
• Open: RESET signal of the inactive CPU socket is connected to GND.

CPU1

• Closed: "CPU1" (left) socket is active.
• Open: "CPU2" (right) socket is active.

Solder Jumper "JP1 - RTC Enable" (bottom of the PCB)

Do NOT leave this jumper open! This jumper must be soldered in the "Enable" or "Disable" position! If left open, RTC and/or clock ports will be unreliable.

You must solder this jumper in the "Disabled" position when another RTC expansion is used anywhere on the computer.

• Soldered in "Enable" position: Mapping of RTC on the on-board FPC connector to $DC0001 is enabled.
• Soldered in "Disable" position: Mapping of RTC on the on-board FPC connector to $DC0001 is disabled.

Parts

Interactive BOM included.

Origins

Based on prior work by Matthias Heinrichs (CPU switch "Garlic") and Rijkyard (socket shift).

License

Free for non-commercial use as per prior work's license.