Greetings, Maarten tur Huurne...
MH>About your CP/M:
>You could consider to make an MSX-DOS1 compatible version.
>From the MSX-DOS2 function call description:
> CPM MSX1 00h - Program terminate
> CPM MSX1* 01h - Console input
> CPM MSX1* 02h - Console output
What do those asterisks ('*') indicate?
I agree, it should be relatively easy to add MSX-DOS functions
to my CP/M-clone, for a hybrid operating system that may run
applications that are otherwise only for MSX-DOS1 or CP/M. And,
ZCPR3 -- which I've already integrated into my CP/M -- provides
some Unix-like features: shells, aliases, i/o redirection, flow
control, search paths, named directories, custom menus, multiple
commands, full online help facilities, etc. (You can find ZCPR3
information from Internet FTP sites, such as oak.oakland.edu.)
I'd like to read opinions from MSX owners who use an ATA/IDE...
Since I've not yet found a satisfactory FDC chip, I'm shelving
my FDC circuit, for now. I'm proceeding with making an ATA/IDE
interface -- first for my Spectravideo, later for my Yamaha.
I'd like to know what MSX owners like, or dislike, about IDEs
they're using now. If I can understand the "good and bad" of
existing IDEs, I might be able to avoid repeating errors, or
maybe even make a good thing better. And, your experiences may
point me towards a good way to implement ATA/IDE for MSX.
Technically, there are numerous ways to go about it -- such as
the traditional approach: A cartridge with ATA circuitry and a
ROM for disk boot and i/o routines. This has the Z-80 do all
the low-level ATA handling. An alternative, that may not have
yet been tried, is a cartridge with a microcontroller which
controls ATA functions -- PIO, sector deblocking and buffering,
DMA, etc. -- and which the Z-80 CPU commands.
Maybe the idea of using a microcontroller seems like too much
trouble, but it depends on development resources. For example,
I'm already developing an 8031 microcontroller circuit for my
SV-328; it takes over the task of scanning the keyboard matrix,
adds buffering, and interrupts the Z-80 only when there's key
data available. The 8031 will interface to a PC keyboard; and,
the 8031 on-board UART can directly accept a serial mouse. This
offloads significant i/o duties from the CPU, giving the Z-80
more computing time, rather than polling extra devices.
Keep in mind that the MSX i/o architecture is effectively a
simplistic polling scheme: It uses the single "Z-80 Mode 1"
interrupt, at a [wasteful] rate of 50 (Europe) or 60 (Canada
and USA) times each second -- polling any and *every* device
that it suspects may (or may not) actually be present!
Your thoughts, Anyone ?
Greg_
http://www.netcom.ca/~telic
98.Sept.11, Toronto, Canada.
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