info-cpm (12/06/82)
>From vortex!lauren@Lbl-Unix Mon Dec 6 13:52:15 1982
To: ELIOT@Mit-Mc
Cc: INFO-CPM@BRL
Via: Lbl-Unix; 6 Dec 82 6:49-EST
Via: Brl; 6 Dec 82 6:53-EST
Via: Brl-Bmd; 6 Dec 82 7:00-EST
Lessee. Currently, the non-overlayable portion of the kernel
is around 14.5K bytes. On my system here, which has a monstrous
hard disk/floppy disk BIOS, I usually have around 46K free for user
programs. I have found this to be large enough for all my work, including
compiling and running my UUCP and mailsystem code. Oh yes, I lose another
couple of K in my system due to reserved space for the MARC BYE program
which supports dialup access to UUCP and the like, so 48K is probably
a more realistic figure for my big BIOS when *not* running in dialup
mode. The CP/M emulator is around 2K bytes, but it only loads when
you need it (when you try to run a program which has the CP/M "tag"
bit set [the same bit used as the "sticky" bit under UNIX]).
Note that user programs under MARC tend to be smaller than under CP/M, since
much terminal and disk I/O code that is duplicated in almost every CP/M
program is unnecessary under MARC, since the MARC kernel provides much
more advanced facilities in those areas than does CP/M.
The kernel is written in 8080 assembler. Investigation showed a trivial
size decrease for conversion to Z80 code, and would have locked out the
people with fast 8085's, so conversion was not attempted. Utility
programs are a mixed bag. Some of them are in assembler and some
(particularly the more recent/complex ones) are in BDS C.
I can only say that during all the work I do here at vortex, I haven't
found the amount of free memory to be a problem. I'm looking into the
issues of putting the kernel in a separate bank of memory, but this
will clearly not happen until after the basic MARC is out and I have some
reason to believe it will be accepted in the marketplace.
--Lauren--info-cpm (12/07/82)
>From ELIOT@Mit-Mc Mon Dec 6 22:29:12 1982
To: vortex!lauren@Lbl-Unix
Cc: INFO-CPM@Mit-Mc
Via: Mit-Mc; 6 Dec 82 19:30-EST
Via: Brl; 6 Dec 82 19:37-EST
Via: Brl-Bmd; 6 Dec 82 19:45-EST
Thanx for the prompt reply. It is not as Big is i had expected it to be.
You continue to talk about a modified BDS-C that comes with MARC (what does
MARC stand for?). Is this modified BDS-C a modification of the most recent
version of BDS-C (V1.5 i think)? You mentioned that some of the utilities
are mixed bag z80 and 8080, are you using a Z80 library for BDS-C? Is there
a Z80 library available for your modification to BDS-C?
How often do YOU use the CPM emulator? It would seem that there is SO much
software for CPM that one might find it hard to go without? How much
is already available (Public Domain) for MARC right NOW?
-Eliot at Mit-DM