; AIMesaMc.mu
; Alto 1822 Interface microcode control program

; Larry Stewart
;   Version for scatter/gather
;   Version for Mesa
;   Modified September 1, 1978  5:10 PM
;   This is a short control program containing nothing but 1822 code
;   Last modified September 8, 1978  9:44 AM
;     to include PREncrypt instruction

#AltoConsts23.mu;

; Ram entry vector, for access via Mesa JRAM instruction.
; Note that only Ram locations 400-777 and 1400-1777 are reachable from Rom1.

%7, 1777, 400, SilentBoot;

%7, 1777, 420, SetConPtr, PREncrypt;

; Reserve 774-1003 for Ram Utility Area.

%7, 1777, 774, RU774, RU775, RU776, RU777, RU1000, RU1001, RU1002, RU1003;

; For the moment, just throw these locations away.  This is done only
; to squelch the "unused predef" warnings that would otherwise occur.
; If we ever run short of Ram, assign these to real instructions somewhere
; in microcode executed only by the Emulator.

RU774:	NOP;
RU775:	NOP;
RU776:	NOP;
RU777:	NOP;
RU1000:	NOP;
RU1001:	NOP;
RU1002:	NOP;
RU1003:	NOP;

; Mesa emulator conventions

$next	$L 4400, 0, 0;	Emulator entry point

$stkp	$R16;	Stack pointer (0 = empty, 10 = full)
$stk0	$R60;	Stack (bottom)

; Initialization for putting this code in the RAM, including
    ; 'silent boot' code

!17,20,Emulator,,,,,IMLOOP,,,,,,,,,,;

; **** Emulator Task ****
    ; Degenerate -- just returns control to emulator in Rom1.

Emulator:
	SWMODE;	Switch to Rom1
	:next;	Mesa emulator entry point

; Microcode subroutines are defined and called from Mesa programs
; as shown in the following example:

; silentBootAddr: CARDINAL = 400B;  -- Ram address of SilentBoot microcode --
; SilentBoot: PROCEDURE[bootLocusVector: WORD] =
;   MACHINE CODE BEGIN
;   Mopcodes.zLIW, silentBootAddr/256, silentBootAdr MOD 256;
;   Mopcodes.zJRAM;
;   END;

; SilentBoot[177376B];  -- the call --

; All these routines assume they are called with a clean stack.
; Hence, an invocation such as "SilentBoot[177376B]" must be written
; as a complete statement, not as an embedded expression.
; If the routine returns a value, it must be called in a statement
; of the form "simpleVariable _ Routine[args]".
; This permits the Ram subroutine to access fixed S-registers for
; arguments and return values.  It must still adjust the stack pointer
; appropriately, however.


; SilentBoot: PROCEDURE[bootLocusVector: WORD]
; Sets the Boot Locus Vector and does a silent boot.
; Entry point is Ram address 400.

SilentBoot:
	RMR_ stk0;	Set BLV from arg on stack
	L_ stkp-1,TASK;	stkp_ stkp-1
	stkp_ L;
	SINK_ 100000,STARTF,:Emulator;	Boot the machine

#PREncrypt.mu;

; **** 1822 Task ****

#Mesa1822.mu;
(0,4798)(1,11959)\b14B467b1B27b1B79b1B673b2B38b26B63b8B1053b10B146b22B