This folder contains the MITS Programming System II monitor updated to use the
2nd port on an 88-2SIO (12h/13h) for cassette I/O instead of the standard 88-SIO
port at 6/7 used by the Altair Cassette Interface. This update includes the
bootstrap loader, the checksum loader on the tape, and the cassette I/O routines
within the PS2 monitor.

To load the PS2 monitor, use the LDR4K32 bootstrap loader present in this folder.
Turn on switches A15, A11, A10, and A9. This specifies port A on the 88-2SIO as
the console and port B on the 2SIO as the "cassette" load port.

You can also load this tape with Martin Eberhard's enhanced version of the MBL
PROM, "MBLe" (the original MBL PROM won't work). Note also that AMON on the
88-2SIOJP has the equivalent of MBLe at its standard address of FE00. To load
the PS2 monitor, set A15-A12 to 0001 to use port A on the 88-2SIO as the console
and set A11-A8 to 0110 to select port B as the load port (cassette). After about
30 seconds of load time has passed, changes the sense switches so that only A11,
A10, and A9 are on.

Martin Eberhard's MBLe PROM can be found here:
https://deramp.com/downloads/altair/software/roms/custom_roms/M%20Eberhard%20Improved%20ROMs/

The PS2 editor, assembler, and debugger are loaded from cassette (the "AC" device)
via the PS2 monitor in the normal fashion. These files are unchanged for this
88-2SIO "cassette" version.

You can write the PS2 tape and files to cassette using the WRTAPE utility on
the "MITS Tapes" CP/M disk image found in the "CPM Utilities for Altair Cassette"
up two folder levels from this folder.