lehmann at ans-netz.de
Tue Jun 3 14:18:07 AEST 2008
I don't know if it's usual or not to write an introduction but I'll just
do so by keeping more an eye on the computer system I own.
If you don't care just skip this mail ;)
As my From header states my name is Oliver, I live in germany and right
now I'm 27 years old. That should be enough to my person - now let me
tell you a bit more about the computer system I own ;)
This system was built between 1987 and the breakdown of the former GDR -
the eastern part of germany - 1990. The system itself is split up into
two "towers" connected together. The first tower called "P8000 Computer"
contains a 8Bit system (Z80) and a 16Bit system (Z8001).The 2nd case -
the "P8000 Winchester" - contains a Winchester Disc Controller which runs
with a Z80 CPU and is connected to the 16Bit part of the "P8000
Computer". Up to three MFM drives (all with the same geometry while the
geometry itself can be configured) can be connected to the WDC.
The 8Bit part is built on a single board, has 64KB SRAM, 2 SIOs to
connect up to 4 terminals to it, one PIO to connect a EPROM programmer,
and one PIO to establish a connection to the 16Bit part. It has 2 5.25"
floppy drives with an external connector to connect two further 5.25" or
8" floppy drives. The systemmonitor is loaded from two 2732 EPROMs.
The system originally supported three operating systems while two
survived the time being. I own UDOS which is a Z80-RIO clone and OS/M
which is a CP/M clone. There also was an OS called IS/M which was an ISIS
The more interesting (at least for me) part is the 16Bit part. The 16Bit
part is built on a single board too (6layer) while the DRAM are single
board which can be hooked up onto the mainboard.
The system runs a Z8001 with 3 MMUs and Z80-peripherial ICs (PIO, SIO...)
It also has 2 SIOs for 4 terminal connections, and one PIO to connect the
WDC. The system also has two furhter PIO chips to establish a connection
to the 8Bit system. The system runs with up to 4MB of DRAM but it might
run with more RAM with self-made RAM modules. There exists also a RTC for
the system and an extension to connect an 80286CPU + 1MBRAM to the 16BIT
port to run a x86 OS on it while stearing it from the OS running on the
The Operating-System running on the 16Bit part is WEGA - a ZiLOG ZEUS
To boot WEGA at first the 8Bit system has to be booted up with UDOS (the
Z80-RIO clone) to load a communication software which handles the
communication over the 8Bit-PIO. After this is done the system switches
over to the 16Bit system and the system monitor there gets loaded. The
WEGA-Kernel (most parts are still original ZEUS objects) itself has the
corresponding part for the 8<->16Bit communication interface in it.
This was done to get access to the floppy drives, the EPROM programmer
and the 4 8Bit-terminal connections which are all connected to the Z80
on the 8Bit-system.
To access for example a floppy, the WEGA-kernel has to send the request
using the PIO connection to the 8Bit system which handles it and sends
the results back to the WEGA-kernel on the 16 Bit system. Same goes with
the WDC which is connected through another PIO directly to the 16Bit
system - command codes are sent to the Z80 on the WDC which handles the
codes and sends the results back to the 16Bit system. Not that fast but
it works good.
Pictures and so one are all collected on my homepage
http://pofo.de/P8000/ while most (if not to say all) of original
documents are written in german...
So - what do I do with the system? I use it for learn more about hardware
processes itself, assembler and to get a deeper UNIX knowledge which is
easier to start with there then with todays UNIX systems.
Las project was to get TCP/IP working and I successed by usingg K5JB to
get FTP and ping to work via SLIP. Because the speed was damn slow (and
not just because of the baud rate), I came to the conclusion that a
better performance could be achieved by implementing TCP/IP in the
kernelspace instead of having it run in the userspace.
So my goal is now to get the kernel sources right now to make the
neccessary changes to get TCP/IP running in the kernel. As you might
think now this is not so easy as it sounds. The sources for some objects
of the kernel survied over the time, but many are missing. I'm now
sitting here since a month disassembling the original kernel object and
writing the disassembled code back in C. I've started this by having lets
say nearly-to-zero ASM knowldege and I'm making good progress. Not much
is left, but from time to time the C files are not compiling to
exactly the same object which is in the kernel. Some times other
temporary registers are used for operations, or I can't get to the same C
code doesn't matter of what I'm trying and so on. I'm trying to get 100%
the same object to be 100% sure I have the same code the object was built
with. The compiler on that system should be the same but of course I
can't guarantee that for sure.
I'll put a web page together with my open C<->ASM questions because I
think I can format things better there so asking and reading would be
easier (probably because it is a lot of text)
My progess can be seen here: http://pofo.de/P8000/kernel.php
And the sources I got so far are here:
I hope you can help me a bit with answering the things I can't find an
answer myself ;)
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