19 Apr
2007
19 Apr
'07
6:34 a.m.
On Apr 18, 2007, at 4:43 PM, Jules Richardson wrote:
Interesting; did CP/M ship with a range of UART and
FDC drivers
then, so you just tell it what particular ICs you're using and at
what port addresses, and away it goes? Or was it more complex than
that, and realistically you'd have to write your own comms / FDC
driver which exposed some defined interface to CP/M itself?
The CP/M distribution, as shipped only boots & runs on one
particular type of machine: an Intel MDS-800 development system. If
you (or a computer manufacturer, say Kaypro for example) wanted your
machine to run CP/M, and it wasn't exactly like the MDS-800 in terms
of what I/O chips were used and at what addresses, you had to write
the drivers to support your hardware. These drivers form the BIOS.
CP/M was shipped with the intention that users would write their own
BIOS code to support their own systems.
In truth it is really not all that difficult. The BIOS interface
is very simple and well-defined. Under the tutelage of an
experienced mentor, I was writing BIOS code on my Imsai when I was
about fourteen. It's nothing like the complexity of, say, a device
driver system for an implementation of UNIX.
-Dave
--
Dave McGuire
Port Charlotte, FL