ROSUNCR.DOC vers 1.0  11jan88
by W. Brimhall  Z-Node 52  (602)996-8739

ROSUNCR.LBR contains the files used to add uncrunch support to my 
ROS 3.4 CP/M 80 system. It was put together in a quick effort to 
share the information with others that do not want to wait for a 
more refined future release.

The main obstacle in uncrunching a file under ROS is the need for 
a 24k free memory buffer. The only solution I could come up with 
was to chain to a separate Turbo pascal .CHN file to perform the 
uncrunch then chain back to the main ROS program. 

For this scheme to work it is necessary to save the present state 
of ROS on the heap during the chain. I was disappointed to find 
that Turbo Pascal does not normally preserve the heap when 
chaining. A wasted 15 min call to Borland technical support 
verified that the heap gets destroyed and provided no help in 
solving the problem. After several hours hours of debugging and 
disassembly I came up with the solution which is detailed in the 
TPHEAP.DOC file. 

The actual UNCREL.Z80 uncrunch subroutine was provided by Steven 
Greenberg. I made many unsuccessful attempts using ZAS vers 3.0 to 
assemble this into the UNCREL.INC format for use with Turbo 
Pascal. I finally discovered that ZAS had a bug with the Turbo 
include mode which prevented it from assembling correctly. I was 
able to patch the assembler to fix the problem and I notified Al 
Hawley who has removed the bug in ZAS vers 3.05.  

For the Pascal uncrunch program to work it must have 24k of free 
memory between the end of its program code and the start of the 
ROS heap. Even on my TurboDOS system with 63k of tpa there was 
not enough free memory. To increase the free memory size it was 
necessary to reduce the heap size of ROS. This was accomplished 
by modifying ROS to read the SECTION.BB# file data directly from 
disk as it is needed instead of storing it in the heap at 
initialization. (The additional access time is hardly 
noticeable.) Free memory space is still a big problem for small 
tpa systems. You must have at least 58k of tpa to run this 
version of ROS. Hopefully some future optimization will reduce 
this figure.

Several of the ROS modules had to be modified to implement the 
uncrunch scheme. The modifications are all documented within the 

than I expected and overall I'm quite pleased with it. Next I'm 
planning to further reduce the tpa requirements and add support 
for .ARC files to allow logging into them just like libraries.

A couple of the .INC files in the ROSUNCR library have also been 
modified for use with TurboDOS. You will most likely want to undo 
these modifications if you are running under CP/M. (These 
modifications are also documented within the files.) 

Good luck and give me a call if you have any questions.