Sinclair QL-SD, Руководство пользователя

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QL-SD User Manual 24
12.1. The Address Map
QL-SD uses a quite a bit of address space in the QL:
$FEE0 - $FFFF QL-SD Hardware register space
$C800 - $FEE0 QL-SD on-board ROM (driver)
$C000 - $C800 Unused by QL-SD (Expansion port ROM & I/O)
$0000 - $C000 Minerva 1.98
It is obvious from the above address map that QL-SD is not compatible with any other QL
extension that uses the 16k ROM slot addresses ($C8000-$FFFF)
12.2. The Hardware
QL-SD’s hardware consists mainly of the Lattice Mach 4000 CPLD, a pretty modern (and fast - it
runs at 50 MHz) reprogrammable logic chip. The CPLD does the address decoding for the various
QL-SD hardware registers that it provides and for the QL-SD EPROM.
The CPLD provides background SPI (Serial Peripheral Interface - The standard used to access SD
cards) transfer to and from the SD card. In its normal mode, the CPLD acts as a serial-to-parallel
converter clocking the 8 bits of one byte directly in and out of the SD card without the need of
further intervention from the QL. (There is, however, SPI mode 0 which allows the QL to directly
access the data and clock lines of the SPI bus - Which is obviously much slower and only used
during driver startup)
As QL-SD lives in ROM space, there is actually no direct way for the QL 68008 CPU to write
access the QL-SD registers. A write of one single byte to QL-SD is thus initiated by a read acess to
a specific QL-SD register bank offset by the value of the byte to be written to QL-SD - The CPLD
translates this into a write into its data register.
13.
Known Issues
13.1.
Hardware
It is (at least at the moment) not recommended to use QL-SD with the SuperGoldCard.
Instabilities have occurred on some of such systems.
QL-SD together with the normal (especially older) Gold Cards might also work
unreliably.
There have been reports of at least one Gold Card user (me, unfortunately) where
QL-SD would not work.
QL-SD will most probably not work with other hardware that uses I/O addresses in the range of
$c800 to $ffff (the ROM slot area) or copy-protected software that wants to see its ROM in this
area (The Eidersoft ICE and mICE suite of programs are known examples)
13.2.
Driver
The QPAC Files Thing may not work.
Partitions that require group sizes larger than 8 degrade performance and have caused
problems on some systems. Group sizes 64 and 128 were affected, but the exact
circumstances of these problems were not known at the time of writing. Please test large
partitions thoroughly on your system before using them for important data. Best stick to