User's Manual

PMAC Dual-Ported RAM User Manual
2 Dual-Ported RAM Communications
P4
P3
U10
4.19 in (106.4 mm)
3.88 in (98.5 MM)
7.50 in (190.5 mm)
PMAC-PC OPTION 2
DUAL-PORTED RAM INTERFACE BOARD
To install the board, connect the cables as previously stated with the boards removed from your computer.
Next, install both boards, plugging in PMAC first and then the DPRAM board in the slot next to it. Turn
on your computer and establish communication with PMAC using the PMAC Executive software. At the
time of this manual revision, the easiest method of configuring the Dual-Ported RAM is using the
Executive Program.
There are only two hardware configurations (set with jumper E1) for the DPRAM card. Jumper E1
controls whether the DPRAM uses 8 or 16-bit access. E1 should be removed for 8-bit access in a 16-bit
PC bus (AT) slot. Install E1 for 16-bit operation (faster data transfers). All other DPRAM configurations
are done entirely through software programming via PMAC.
Software Setup
The software setup is simply a matter of setting a few register values in PMAC through the normal bus
communications port, and saving these values to non-volatile memory. This should allow the host
computer to have direct access to this memory in an open area of its memory space. Once the setup has
been made successfully, the DPRAM registers can be accessed from the PC side with pointer variables.
The configuration of the DPRAM is done entirely through software. Configuring consists of selecting an
16K block (byte addressing) of unused memory space in your PC. This is not necessarily a trivial task.
Depending on the computer and other accessory cards you may have (such as network cards, graphic
cards, etc. that use conventional memory space and not I/O memory space), the available memory space
location may vary. Think of it as adding a standard memory card to the computer where an address
location must be selected in the memory map that no other device in the computer uses.
If you are unsure about the locations available for DPRAM to use, there is menu option Configure|PC
Dual-Ported RAM under the Configure menu in the PMAC Executive Program which can help find an
available block of memory space. Refer to the PMAC Executive Program Manual for details on how to do
this. In most cases, the available memory space will be found between locations $B0000 and $EC000.
Usually, a system memory map of the PC which is standard for most PCs and compatible is found below.