Message-ID: <948@psuvax.UUCP>
Date: Wed, 4-Apr-84 13:17:51 EST
Article-I.D.: psuvax.948
Posted: Wed Apr  4 13:17:51 1984
Date-Received: Thu, 5-Apr-84 02:00:40 EST
Organization: Pennsylvania State Univ.
Lines: 119

This article contains information about the monitor commands and the
character set for the video display.


This is a list of the functions provided by the monitor for the Xerox 820.
They are accessable on powerup from the keyboard.

Command	Use
-------	-------------------------------------------------------------
Dump	Dad1 ad2
	Dumps addresses ad1 through ad2.  If ad1 is omitted, dumps
	0000 through ad2.  Output can be held/restarted by hitting
	a key.  2 CR's will stop function and return to monitor if
	you don't want to see the whole dump.

Memory	Mad1
	Prints contents of location ad1, and accepts changes.  To
	change, just type the new value (2 digits), to skip forward
	use CR, to skip backward use '-', any other to exit.

Xtest	Xad1 ad2
	Test for memory errors.  Prints a '+' each time a cycle is
	completed, 256 cycles for every combination to be tested.
	Prints bad addresses if it finds any. Dumb name for command.

Fill	Fad1 ad2 val
	Fills memory ad1 through ad2 with val.  Reads block back to
	check for memory errors and reports any if found.

Copy	Cad1 ad2 ad3
	Copies memory from ad1 through ad2 to memory starting at ad3.
	Compares copy with original and reports any differences to
	check for memory errors.

Goto	Gad1
	Does a CALL to ad1.  Control can be passed back to the monitor
	with a RET instruction.

Read	Runit trk sect
	Reads a sector from disk and prints it in dump format.  If an
	error occurs, it lets you know.  'disk error XX Uaa Tbb Scc'
	is the error where aa=unit number, bb=track number, cc=sector
	number, and XX is the 1771 error code:

	bit	R/W		Seek/Restore/Select
	---	------------	--------------------
	7	Drive not ready	Drive not ready
	6	WR Protected	(not used)
	5	WR Fault	(not used)
	4	Not found	Seek error
	3	CRC error	CRC error
	2	Lost data	Cannot restore
	1	(not used)	(not used)
	0	=1		=0

Boot	B (or A)
	Loads bootstrap loader from disk and jumps to it.  Reads tr0 sec1
	into 0080 and then jumps to 0080.  Loader cannot use bottom 256
	bytes of memory.

Type	T
	Converts millions(?) of dollars in research into an electric
	typewriter.  Reads from keyboard and outputs to printer port.
	Does not output to CRT.

Input	Iport
	Inputs byte from specified port and displays it.  CR will do the
	same for the next port, '-' will do it for the previous port, any
	other exits.

Out	Oport val
	Outputs value to specified port and returns to monitor.  Useful for
	initializing ports.

-----------------------------------------------------------------------------

CRT information

Control characters

Hex	Use
---	----------------------------------------------------------------------
00-07	None
08	Cursor left
09	Horizontal tab (tab stop every 8 postions)
0A	Linefeed
0B	Cursor up (wraps back to bottom of screen)
0C	Cursor right
0D	Carriage return
0E-10	None
11	Clear to end of screen
12-17	None
18	Clear to end of line
19	None
1A	Clear Screen
1B	Escape
1C-1D	None
1E	Home cursor
1F	Print char between 00 & 1F (special characters)

ESC is used for XY cursor positioning.  ESC+'='+rowchar+colchar is the form
where rowchar and colchar is the desired row/col with 32 added to it (20 hex).

The special characters are hidden in the control character section.  To print
a special character, prefix it with 1F.  To print more than one, prefix each
one with 1F.

The character set is standard ASCII from 20-7F.  The character set is repeated
in 80-FF with a blink attribute.  If the cursor is on a blank spot, the 
standard block cursor will be displayed.  If the cursor is on a character, the
blinking version of the character will automatically be displayed.

---
Overall there is a smell of fried onions.  (fnord)

                                 :+: Pat Mancuso
                                 :+: Penn State University
                        Usenet:  :+: ...!psuvax!mancuso
                        Bitnet:  :+: mancuso@psuvax1