Notes on OSI ROMS
by Mark Spankus

BASIC1.ROM    - image of 1st 2K basic rom 
BASIC2.ROM    - image of 2nd 2K basic rom
BASIC3.ROM    - image of 3rd 2k basic rom
BASIC4.ROM    - image of 4th 2K basic rom
OSIBASIC.ROM  - combined 8K image of basic at $A000
CEGMON.ROM    - C2E replacement monitor rom (uses nonstandard mapping)
CHARGEN.ROM   - character generator for OSI540 board
OSI_IBM.ROM   - IBM character set in OSI540 compatible format
OSIHIRES.ROM  - block graphics character set for plotting
SYN600.ROM    - OSI monitor rom for multiple systems

SYN600 Notes:
The 3 of the 8 256 byte pages in this rom are mapped into 3 areas
of the computers, $FD00, $FE00, and $FF00.  Different pages are
used depending on the system. (Tape based, Disk based, model etc.)
The $FD00 page is for the polled keyboard. The $FF00 page sets the
IRQ, NMI & RST vectors and does the initial startup, the $FE00 page
contains part of the tiny monitor & tape I/O etc.

page 000 'H/D/M'   maps to $FF00 for a C2/C4 disk system
page 100 keypoller maps to $FD00 for a C2/C4 system
page 200 monitor   maps to $FE00 for a C2/C4 system
page 300 'C/W/M'   maps to $FF00 for a C2/C4 tape system
page 400 ??
page 500 keypoller maps to $FD00 (for a C1 system?)
page 600 monitor   maps to $FE00 (for a C1 system?)
page 700 'D/C/W/M' maps to $FF00 for a C1 system

On a C2/C4 system:
ACIA is at $FC00-FCFF
Keyboard at $DF00-DFFF
Video $D000-D7FF, Color at $E000-E7FF
Disk PIA, ACIA $C000-C0FF
Basic ROM $A000-BFFF

On a C1 system: (not sure if correct)
ACIA at $F000
Disk Prom at $F800
Keyboard at $DF00-DFFF
Video $D000-D3FF