Newbie Hardware Questions

[Theo Markettos]

On Thu, 27 Jun 2002, Richard Smith wrote:

> Presumuably a 5V linear flash card (definately not ATA) or a SRAM card
> would take the least board hacking.  You'd probably need to disconnect
> D16-31, but apart from that I can see no obvious reason why they wouldn't
> work.  It's certainly an interesting possibility for those of us without
> appropiate EPROM programmers.  A battery backed SRAM card would be ideal,
> since it could be programmed on another PCMCIA device.

As a first step I've opened up my NC OS flash card.  One thing that was
concerning me was that the PCMCIA cards appears to be 16 bits wide, whilst
the RISC OS card has to be 32 bits wide to run RISC OS out of.  The NC OS
card is indeed an Acorn special (Acorn Network Computing 4MB flash card,
2103,004 Issue A says the PCB), with two Intel 28F016SV devices (rated
70ns at 5V or 120ns at 3.3V).  So it might be possible to attach a flash
card, but needs two connecting at once to provide a 32 bit data bus.  It
_might_ be possible to hack up something that reads two 16 bit words from
a card in one bus read cycle, but would probably need faster flash to do
this (I haven't looked at the 7500's timing diagrams to investigate this
though), and at least an 8MB card.

So as usual, nothing is as simple as it might be... :-(

Theo