Symbolic language data processing system
or the Symbolics patent 4,887,235


a memory
  4k x 40 bits
b memory
  256 x 40 bits

registers

STKP, FRMP, and XBAS - can be used to access a memory

sequencer
	8k x 112bits control store

8 hardware tasks

Task 0 Emulator, Wakeup request is always true.

Tasks 1, 2, 5, 8 Software. Wakeup requests are in a register; bit n can be set by doing a special function. One of these tasks is the background service task for all DMA tasks (set up next address and word count); the others remain unassigned.

Task 3 FEP service (wakeup settable by FEP)

Task 4 Low-speed devices; wakeup request from open-collector bus line.

Task 7 Not used. The task state memory for this task is available for the FEP to clobber for debugging purposes. The only way this can become the current task is by the FEP forcing it.

Tasks 8-15 DMA or I/O tasks. Assigned to devices during boot time wakeup requests come from open-collector bus lines.

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Trap address interpretation:
Bit 12 is the skip bit; Bits 8-11 are the dispatch bits. Bits 0-7 are capable of incrementing. 

---

A-memory map:

0000-1777 stack buffer
2000-2377 variables
2400-2437 CURRENT-STACK-GROUP-DATA
2440-2477 OTHER-STACK-GROUP-DATA
2500-2577 MICROCODE-CONSTANTS
2600-2677 MICROCODE-ESCAPE-ROUTINES
2700-2777 MICROCODE-ESCAPE-CONSTANTS
3000-3377 microcode internal constants allocated by microcode linker
3400-3677 microcode internal variables (allocated by DEFAREG)
3700-3741 function call history (not used)
3742-3777 not used
4000-5777 auxiliary stack buffer (for paging and sequence-break/interrupt code)
6000-7777 reserved

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Headers tagged with DTP-HEADER-P
*HEADER-P-TYPES*
0	%HEADER-TYPE-SYMBOL			Address of pname string
1	%HEADER-TYPE-INSTANCE			Address of instance-descriptor array

Headers tagged with DTP-HEADER-I
*HEADER-I-TYPES*
0	%HEADER-TYPE-COMPILED-FUNCTION
1	%HEADER-TYPE-ARRAY
2	%HEADER-TYPE-NUMBER


compiled-function

4 header words

1:
	The header word, with DTP-HEADER-I, %HEADER-TYPE-COMPILED-FUNCTION
	COMPILED-FUNCTION-TABLE-SIZE 8 0	number of ext refs and constants
	COMPILED-FUNCTION-TOTAL-SIZE 16 8	number of words total
	COMPILED-FUNCTION-SPARE-BITS-1 4 24
	
2:
	a fixnum containing 32 more bits of junk
	COMPILED-FUNCTION-HEADER-WORD-2	The whole fixnum
	COMPILED-FUNCTION-ARGS-INFO 18 0	%ARGS-INFO data, see below
	CCA-CURRENT-DEFINITION-P 1 18
	COMPILED-FUNCTION-SPARE-BITS-2 9 19
	COMPILED-FUNCTION-LANGUAGE-INDEX 4 28
3:
	The third header word, a cons of function name and debug-info a-list.
	Valid keys in the debug-info not yet defined, but "like A-machine"
	All the data not needed during normal execution are in here.
	&QUOTE data will be needed in here, also (unless just &QUOTE &REST)
	COMPILED-FUNCTION-EXTRA-INFO
4:
	The fourth header word; the function cell of the symbol that names the
	function can be relocated to here to optimize working-set size
	COMPILED-FUNCTION-FUNCTION-CELL