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Inter-Office MellloranduIll

To Alto Maintainers Date January 27, 1975

From Ed McCreight location Palo Alto

Subject Reserved AI to Memory Locat ions Organ i zat ionCSL

/\ . 1\

I have resisted this memo as long as possible. However it now seems that
without it programs will soon begin stepping on each others' private special
reserved Alto memory locations. This memo purports to list the entire set of
I 0 cat ion s w11 i c h are bel i e \' edt abe pre s e r v e d a c r 0 S S sub s y s t e'm c a lIs, a l' wh i c h
dre held to be special by hardware or microcode. If you know of other
locations which should be in this list, please let me know. The czar carries
the heavy burden bf adjudicating.territorial disputes,for which h~ hopes h-
will not need the wisdom of Solomon.

Page 0:
UO - #17: Set to #77400 (SWAT - Morris)

'Page 1:
11420: Display List Header (Std. Microcode - Thacker)
11421: Display Interrupt Hitword (Std. Microcode - Thacker)
11422: Interval Timer Stored Quantity (Std. Microcode - Thacker)
11423: Interval Timer Bi,tword (Std. Microcode '- ,Thacker)
#424: Mouse X coordinate (Std. Microcode - Thacker)
#425: Mouse Y coordinate (Std. Microcode - Thacker)
#426: Cursor X coordinate (Std. Microcode - Thacker)
11427: Cur s 0 r Y coo r d i 11 ate (S t d. Mi c ,r 0 cod e - Thac k e r )
11430: Real Time Clock (Std. Microcode - Thacker)
/1431 - 11450: Cursor' bitmap (Std. Microcode - Thacker)
11452: Interrupt,wakeups waiting (Std. Microcode - Thacker)
#453: Active interrupt bitword (Std. Microcode - Thacker)
#'157 : a (extension of Mask Table) (Lisp Microcode - Deutsch)
11460 - #477: Mask Table for Convert (Std. Microcode - Thacker)
11500: Saved interrupt PC (Std. Microcode - Thacker)
U501 - #517: Interrupt Transfer Vector (Std. Microcode - Thacker)
#511: SWAT Interrupt (SKAT - Morris)
11521: Disk command block header (Std. Microcode - McCreight)
#522: Disk status (Std. Microcode - McCreight)
11523: Disk address of latest command (Std. Microcode - McCreight)
11524: Disk sector interrupt bitword (Std. Microcode - McCreight)
11525: I n t e r v a.l t i rile r tim e (S t d. M c roc 0 d e - Thac k e r )
11527: Trap saved PC (Std. Microcode - Thacker)
#530 - #567: Trap vector (Std. Microcode - Thacker)
11567: SKAT Breakpoint Trap (SWAT - Morris) ,
11572 - 11577 : T i III e r so f twa r e ( boo t s h 0 u I d n 't dis t u r b) ( De u t s c h)
11600: Ethe r net po s t I 0 cat ion' (S' t d. Mi c roc 0 d e - ~I etc a 1f e )
/1601 : Ethernet interr~pt bit mask (Std. Microcode - Metcalfe)
IIG02: Ethernet EDT count (Sid. Microcode - Me,tcalfe)
11603: Ethernet load location