6 PC card devices

PC Cards have two sorts of hardware. Real - items which are physically present on the card.   Hosted - items which are shared with the host computer. Which devices are which depends on the sort of PC card you have. The keyboard, mouse, floppy and video are hosted for all PC cards. The hard disk usually is, any extra devices like CD-ROMs and sound cards also will be.  On the second processor card everything except the coprocessor is hosted hardware.  On the Expansion card the memory, serial port(s), parallel port, and optionally the coprocessor, and local hard drive are real hardware. We will describe all the hardware options here. Particularly, we describe anything that differs from a typical PC because it is hosted. In general devices can be treated exactly as they would on an equivalent PC, so if there are no specific instructions here, just follow the instructions in your DOS or device documentation.

6.1 PC cards themselves

PC expansion cards

The PC expansion card consists of a 486SLC or 486SLC2 processor, a single-chip PC motherboard, RAM and several peripheral interfaces: IDE connector, serial port, parallel printer port and the Acorn computer interface. Several hardware upgrades are possible; they are discussed below.

Second processor cards

Second processor cards consist of a CPU and an ASIC which includes the functionality of a PC motherboard chipset and the interface to the Acorn Open Bus. It also has level 2 cache RAM on board.  The Mark I Aleph One second processor PC Card uses a Cyrix DX40, DX2/66 or DX2/80 CPU. These CPUs are used in write-back cache mode and operate at 5V. Note that the write-back cacheing is extremely important to the performance of the chip, and other CPUs which do not have this facility will go much more slowly, (an Intel DX2/66 for example will go at about one third the speed of a Cyrix DX2/66). Thus chip upgrades are not possible unless faster 5V write-back cache chips are produced.    The Mark II Aleph One second processor PC card can take a wide range of 3.3-5V processors. Note that processor upgrades must be handled by Aleph One as changes are required to the CPU core voltage, CPU interface voltage, BIOS support, CPU speed, ASIC speed, and a large number of links. Attempts to change processors without a complete understanding of the details is very likely to damage expensive components.

Aleph One Ltd.

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