More PDP 11 hacking (help!)

[Pete Turnbull]

On Feb 8 2005, 16:10, Vintage Computer Festival wrote:
> On Tue, 8 Feb 2005, Pete Turnbull wrote:

> > If it helps, I can give you an annotated copy of the RXV21
bootstrap.
> >  I've posted it here before, but I can do it again.  I've got other
> > noddy toggle-in programs, for example one that prints out all the
valid
> > addresses in the I/O page, and I have a listing of the standard
> > addresses and what uses them.
>
> All this information would be highly useful to me, and posting it
here to
> the list will probably help someone else down the road, so please do
post
> it.

Ok, here are a couple, starting with the RXV21 bootstrap.  The rest are
on my website, at http://www.dunnington.u-net.com/public/ODT/Listings/
In the directory above that, you'll find some other useful things, like
an opcode list, and a list of common I/O addresses and device
registers.

     1 000000           ; RXV21_boot     From Microcomputer Interfaces
Handbook 1983-84, page 484 (corrected)
     2 000000           ;                Use ODT to enter, then set
RS=340, R6=1000, R7=1000, then P
     3 000000           ;
     4 000000                      ORG      O1000
     5 001000           ;
     6 001000 012700               MOV      #O100240,R0
     6 001002 100240
     7 001004 012701               MOV      #O177170,R1       ; RXCSR
     7 001006 177170
     8 001010 005002               CLR      R2
     9 001012 012705               MOV      #O200,R5
     9 001014 000200
    10 001016 012704               MOV      #O401,R4          ; track
1, sector 1
    10 001020 000401
    11 001022 012703               MOV      #O177172,R3       ; RXDBR
    11 001024 177172
    12 001026 030011               BIT      R0,(R1)
    13 001030 001776               BEQ      $-4               ; wait
for DONE or ERR
    14 001032 100437               BMI      O1132             ; branch
to HALT if ERR set
    15 001034 012711               MOV      #O407,(R1)        ; set
DDens, Read, Go
    15 001036 000407
    16 001040 030011               BIT      R0,(R1)           ; wait
for TransferRequest or ERR
    17 001042 001776               BEQ      $-4
    18 001044 100432               BMI      O1132             ; branch
if ERR set
    19 001046 110413               MOVB     R4,(R3)           ; give
sector number
    20 001050 000304               SWAB     R4                ; swap
track and sector
    21 001052 030011               BIT      R0,(R1)           ; wait
for TR or ERR
    22 001054 001776               BEQ      $-4
    23 001056 110413               MOVB     R4,(R3)           ; give
track number
    24 001060 000304               SWAB     R4                ; swap
sector and track
    25 001062 030011               BIT      R0,(R1)           ; wait
for DONE or ERR
    26 001064 001776               BEQ      $-4
    27 001066 100421               BMI      O1132             ; branch
if ERR set
    28 001070 012711               MOV      #O403,(R1)        ;
EmptyBuffer (DDens) command
    28 001072 000403
    29 001074 030011               BIT      R0,(R1)           ; wait
for TR or ERR
    30 001076 001776               BEQ      $-4
    31 001100 100414               BMI      O1132             ; branch
if ERR set
    32 001102 010513               MOV      R5,(R3)           ; set
word count=128
    33 001104 030011               BIT      R0,(R1)           ; wait
for DONE or ERR
    34 001106 001776               BEQ      $-4
    35 001110 100410               BMI      O1132             ; branch
if ERR set
    36 001112 010213               MOV      R2,(R3)           ; set
address=0
    37 001114 060502               ADD      R5,R2             ;
increment...
    38 001116 060502               ADD      R5,R2             ;
...address
    39 001120 122424               CMPB     (R4)+,(R4)+       ; bump R4
by 2
    40 001122 120427               CMPB     R4,#3             ; sectors
1 and 3 get done
    40 001124 000003
    41 001126 003737               BLE      O1026             ; loop if
not finished
    42 001130 012700               MOV      #0,R0
    42 001132 000000
    43 001134 005007               CLR      PC                ; go to
address zero


    1 000000           ; > ECHO tests console by echoing characters
     2 000000           ;   Uses polling to check UART is free
     3 000000           ;
     4 000000                   ORG     O1000
     5 001000 033727    GET:    BIT     @#O177560,#200  ; test RCSR -
bit7 set=char rec'd
     5 001002 177560
     5 001004 000310
     6 001006 001774            BEQ     GET
     7 001010 013701            MOV     @#O177562,R1    ; get character
     7 001012 177562
     8 001014 033727    SND:    BIT     @#O177564,#200  ; test TCSR -
bit7 set=ready
     8 001016 177564
     8 001020 000310
     9 001022 001774            BEQ     SND
    10 001024 010137            MOV     R1,@#O177566    ; send
character
    10 001026 177566
    11 001030 000763            BR      GET             ; repeat
continuously


-- 
Pete						Peter Turnbull
						Network Manager
						University of York