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Memory Allocation, Limitations and Problems

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Aleph One Recommendations.
Memory Limits
  • Including memery limitations with the Kinetic.
Configuration
Problems

Aleph One Recommendations

PC software is very memory-hungry and because memory is so cheap we suggest that you fit the maximum amount of memory that your PC card or podule can use.

Also remember that the Acorn host will require enough memory to operate correctly. If you wish to use third party software like Acorn's PC Exchange you will need additional free RISC OS memory for this to function, especially for large file transfer on the fly.

Memory Limits

PC card and the Acorn RiscPC Hosting System

All modern PC cards can only be fitted into Acorn RiscPC's. The hosting RiscPC can have as much as 256MB of memory fitted to the mother board. Although adding a Kinetic card can add another 128Mb, the PC card can only use the memory on the main mother board.

The PC card is allocated memory from the host system memory using !PCconfig, to an upper limit of 32MB, set by the design of the ASIC mounted on to the PC card. First and second generation PC cards (Gemini I and Gemini II) have the same limitation. After allocating some of its main memory for use by the PC card you must have at least 4Mb of free memory remaining, but 8Mb or more is better if you do not have a Kinetic card fitted.

Due to the demands of PC software allocating 32Mb of memory is recommended. You may need to install more mother board mounted memory in the host RiscPC to achieve it. You must remember that even if you have a Kinetic card you can only allocate memory to the PC card from that which is mounted on the mother board and not the Kinetic.

Acorn 3.11 RISC OS System

All PC podule cards will only work with older Acorn RISC OS systems. The designed memory limit of the host is 4MB which is sufficient for the host, as the podules have their own on board memory. There is a 3rd party hardware upgrade for the host that will allow a maximum of 8MB, but it is not required for the podules to function.

Elvis (Second generation podule cards)

These podule cards have use SIMMs all of them can use 8Mb but many need a modification to enable them to use the maximum 16MB SIMM. The modification can be done by anybody capable of using a fine soldering iron. Modification diagram download.

Diva (First generation podule cards)

These have the older ZIP type of RAM chips with a maximum of 4Mb.

Memory Configuration Window


Memory Config Window. This screen display shows the Memory configuration window for the PCPro 3 version, now on sale.


The memory configuration window shows the amount of memory fitted in the host system, together with the amount of free memory available and the setting for the amount of memory that will be allocated to the PC card when it starts. It also displays, and allows you to alter, how much of that PC Card memory will be used by the screen display.

PCPro3.xx Configurations only


The "Lower limit for display memory" should be set as high as the VRAM fitted in the host Risc PC. This is subtracted from the memory allocated to the PC card when and if the "Include VRAM for VESA 2.0/DirectDraw support" has been selected. This option is required for the more up to date display drivers. If the "Lower limit for display memory" is set too low, high colour modes can take some time to display.

Problems


If you have a StrongARM and any version of the PCPro prior to !PC 2.13 you will get a memory allocation error if you try to access more than 24MB. You need the free upgrade to 2.13 to overcome this problem and raise the maximum allocation to 32MB.

Some users have had difficulties with SIMMs purchased from differing suppliers, when the PC card is used. This is because blocks of memory larger than usual for RISC OS applications get allocated, and slight inconsistencies in the memory can prevent it working correctly. One large single SIMM is better than two individual SIMM's. This insures that the memory allocated to the PC card is all from one SIMM.

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