To the 2901 bit slicers out there

[Jon Elson]

> On 28.12.2017 05:35, Randy Dawson via cctalk wrote:
>> What about the coding tools?  ADASM? Looks long gone, how 
>> do you do microcode today?
>>
>
>
Oh, I first started out with an assembler macro hack, but it 
was insanely cumbersome, due to the limits of the macro 
capability of the Z-80 assembler I was using.

I then wrote a micro-assembler in Pascal.  It was better, 
but still pretty cumbersome.  There's a good chance that if 
I actually had gotten to writing the full 360 microcode I 
would have come up with improvements.

Here's a little test program for the old asm macro-based 
assembler:

;DIM LIGHT PROG FOR MICRO ASSEMBLER
     MACLIB    UASM
     INIT
;  DEFINE 2 CONSTANTS IN SCRATCH PAD
SPONE    DEFCON    1
SP4096    DEFCON    4096
;  END OF CONSTANTS
DIM    REGS    GPR0,GPR0,GPR0        ;CLEAR GPR0
     FUNC    ZERO
     CTRL    CONT
     GEN
     REGS    ACONST,GPR1,GPR1    ;COPY SPONE TO GPR1
     DEST    PASSWRT
     FUNC    APLUSCY
     CONST    SPONE
     CTRL    CONT
     GEN
     REGS    ACONST,GPR3,GPR3    ;COPY SP4096 TO GPR3
     DEST    PASSWRT
     FUNC    APLUSCY
     CONST    SP4096
     CTRL    CONT
     GEN
BIGLP    REGS    GPR0,GPR0,GPR0        ;INC GPR0, MOVE TO 
COUNTER
     DEST    PASSWRT
     FUNC    APLUSCY
     CY    ONE
     CTRL    LDRCONT
     NA    0,I            ;CBUS => CTR
     GEN
HILOOP    REGS    GPR2,GPR2,GPR2        ;ALL ONES TO CBUS
     DEST    PASSWRT
     FUNC    ALLONE
     CTRL    REPLNA
     NA    HILOOP

The GEN command generates one micro-instruction word from 
all the keywords above it.


Here's what my 2nd gen Pascal micro-assembler code looked like :
     CODE
;    TITLE    muldiv
;This program does multiply and divide on 2903/2904 32 bit CPU
; UNSIGNED MULTIPLY 32 X 32 => 64
; CLEAR R0 FOR MS PRODUCT
; MULTIPLICAND IN R1, MULTIPLIER IN R2
; PRODUCT IN R0 (MS) AND R1 (LS)
     ORG    0
UMULT    R=GPR0,GPR0,GPR0,F=ZERO,D=W        ;CLEAR GPR0
     R=GPR2,GPR2,GPR2,D=LDQ&W,F=A+CY,Q=LDRCONT,N=31    ;mOVE 
MPLIER TO Q REG
                         ;#MPLY CYCLES -1 => CTR
UMLP    R=GPR1,GPR0,GPR0,D=MPYUSG,F=SPEC,Q=REPLNA,N=UMLP
;*****    SHFT    USGMPY
     R=GPR1,GPR1,GPR1,F=Q+CY,D=W        ;COPY LS PROD IN Q TO R1
UWAIT    D=PASS,F=ZERO,Q=JUMP,N=UWAIT        ;hang for user 
to check result
; END OF UNSIGNED MULTIPLY
;
;
; SIGNED MULTIPLY 32 X 32 => 64
; CLEAR R0 FOR MS PRODUCT
; MULTIPLICAND IN R1, MULTIPLIER IN R2
; PRODUCT IN R0 (MS) AND R1 (LS)
SMULT    r=GPR0,GPR0,GPR0,F=ZERO,D=W        ;CLEAR GPR0
     r=GPR2,GPR2,GPR2,D=LDQ&W,F=A+CY,Q=LDRCONT,N=30 ;mOVE 
MPLIER TO Q REG
                             ;#MPLY CYCLES -2 => CTR
SMLP    r=GPR1,GPR0,GPR0,D=MPY2CM,F=SPEC,Q=REPLNA,N=SMLP ;2S 
COMPL MPY
;*****    SHFT    MPY2CM
     r=GPR1,GPR0,GPR0,D=MPY2LST,F=SPEC    ;2S COMPL MPY LAST 
CYCLE
     r=GPR1,GPR1,GPR1,F=Q+CY,D=W        ;COPY LS PROD IN Q TO R1
SWAIT    D=PASS,F=ZERO,Q=JUMP,N=SWAIT        ;hang for user 
to check result
; END OF UNSIGNED MULTIPLY
     END

This tests the multiply functions on the 2903.  The tab 
formatting got messed up pasting this here,
it looked better in the original form.

Jon