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PC Card devices

6.4 Numeric coprocessor
Some DOS programs using floating-point numbers will require a numeric coprocessor to run; many others will simply run faster if a numeric coprocessor is fitted. There is no equivalent to the Floating Point Emulator for DOS programs, so you may have to have one of these chips to run certain programs at all. 

Coprocessors are automatically detected by the software and you need take no action to ensure their use.

PC expansion cards

 
 
 
 

An optional 387SX numeric coprocessor may be added simply by plugging it into the vacant socket on the PC card. It must be inserted in a static-free environment and in the correct orientation – you should therefore ask your dealer to do this for you if you are in any way uncertain about the procedure. 
  • If you perform this upgrade for yourself be warned that Aleph One will not entertain warranty claims for incompetent fitting. 
Be sure to use a 387SX numeric coprocessor rated at no less speed than the main 486 processor; this will normally be 25MHz but a 33MHz or 40 MHz chip will also work.These speeds will also work with the clock-doubled 486/50 card, because the PC Card speed is still 25MHz. 

Check carefully that the bevelled corner of the chip mates with the same corner of the socket before pushing it home: once fitted, a special tool is required to remove it.

Second processor cards

The Cyrix DX CPUs have a coprocessor built in (that is the meaning of the DX appellation). There is therefore no need to add an extra chip to perform this function.

6.5 PC memory
It is useful to understand the the various areas of memory involved in the PC card. There is the memory that the PC thinks it has – the PC RAM. This is the biggest block by far. Then there is the memory used in the host by the !PC application, and supporting items such as video modes and device support modules (Directparallel, etc). 

The PC RAM is described below. 

The !PC application itself uses about 420K in the host. VideoRAM is a minimum of 256K, rising with big modes and space reserved for blitting. See Allocating RAM for video modes on page 44 for details of the VideoRAM allocation.

PC expansion card memory

The PC Expansion card does not share its PC memory with the host computer. It has its own on board which can only be used by the PC Expansion card. 

The PC expansion card uses RAM in the form of a single 32-bit SIMM. This must have the following general characteristics in order to operate correctly: 
 

  • 72-pin SIMM format

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  • 32- or 36-bit memory width (either will work, 32-bit is cheaper)

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  • access time of 70nS or less

    •  
  • Memory capacity of 512K¥32 (2MB), 1MB¥32 (4MB), 2MB¥32 (8MB) or 4MB¥32 (16MB). 

    •  
  • 8MB SIMMs must be of the 16- or 20- chip variety. More modern 4-chip SIMMs cannot be used.
It is recommended that you fit at least 4MB in order to run Windows and applications.

To change memory, first remove the existing SIMM by freeing the retaining clips at either end and prying up the SIMM. Now alter the memory jumpers next to JP15 so that jumpers are fitted in the combinations in the diagram above. 

Note that some SIMMs which have ICs mounted on both sides may require the jumper posts to be trimmed down with side cutters to allow the jumper to clear the rear of the SIMM. 

You may prefer to have memory upgrades performed by your dealer. If you perform the upgrade yourself you should take great care to avoid static electricity and not to damage the SIMM or the PC Card. 

Thus a PC card with 4MB RAM, using video mode x800y600c256 with an extra 250K for blitting will use: 

         420K for !PC application 
         + 472K for PC screen 
         + 250K for screen blitting 
         = 1142K host RAM 
         and 4096K RAM on the PC Card itself

Memory and second processor cards

The second processor cards do not have their own RAM. Use the PCRAM option in !PCconfig to specify how much of the host machine's RAM the PC card can use. This value does not include any host or video memory.

Thus a PC card with 4MB RAM, and using video mode x800y600c256 with an extra 250K for blitting will use: 

           4,096K for PC RAM 
           + 420K for !PC application 
           + 472K for PC screen 
           + 250K for screen blitting 
           = 5,238K of host RAM.
The PCRAM setting is used to define how big the memory of the PC is. Enter a value in Mbytes – do not enter the M on the end).  Typical values are 4, 8, 12, 16. 

You can specify any value you like, but the PC card can only handle a limited number of chunks of memory so the number must be rounded to the nearest achievable value, and it always rounds down. The smallest possible memory is 1 (1MB), and the largest is 32(32MB). Given these criteria the possible sizes of actual memory are: 

  • 1MB, 2MB, 3MB, 4MB, 5MB, 6MB, 7MB, 8MB.
  • 10MB, 12MB, 14MB, 16MB, 20MB, 24MB, 28MB, 32MB.
Of course, the host machine must have enough RAM to supply the PC card’s requirements. 
 

Aleph One Ltd. 50-53

 
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