DM41X Progs

• from HP343C handbook
• DM41X version uses SOLVE and INTEG from Advantage Pac

1. Create a MYSOLVE wrapper that handles putting the correct SOLVE program name in ALPHA etc
2. Create the program that is to be solved and which has as it's function an integral
3. Create the program that defines the integral

LBL ¬MYSOLVE
¬MOD                    // the label of the program to be solved is put in ALPHA
SOLVE                   // we XEQ SOLVE (the Advantage Pac solver)
RTN

The program to be solved

LBL ¬MOD
¬BESSEL           // We put the name of the program with the integral in ALPHA
STO 00            // We store our current guess for X in R 00 to be accessible by the integral finction
0                 // put upper and lower limits for the integration in Y and X
PI
INTEG             // xeq INTEG from Advantage Pac
ABS               // our current guess, make it positive
X<=Y?             // Y has the Integration's estimate of accuracy - we use this to limit our search
ClX               // if our guess has returned a value from the integral that's less than the inherent accuracy then that's GOOD ENOUGH, we set X to zero and SOLVE completes     
X≠0?              // if we still don't have zero we put back the last guess and SOLVE continues
LastX
RTN

LBL ¬BESSEL
SIN
RCL 00
*
COS
PI
/
RTN

MEMO

By Gary Goodman from HP document collection. Dated 24/3/85

for VIA Tone generator

Needs Ladybug module

The required count is calculated from Φ2 and the audio frequency required.

Count (decimal)

{ Φ₂ / ( 2 x F ) } - 2

for 1000Hz and a 1MHz Φ₂ :

Count = { 1,000,000 / ( 2 X 1000 ) } - 2 = 498

498d → $01F2

Run as XEQALPHATIALPHA

Prompt F for required audio tone frequency.

Enter freq

R/S

Result is the 2-byte value for T1CL & T1CH

e.g.

XEQALPHATIALPHA

1000 

R/S

Result:

$001F2

The Counter should be set to

T1CH = $01
T1CL = $F2

Entered as follows (make sure you're in DECS mode in Ladybug while entering the program - otherwise the 1000000 won't be interpreted correctly). When viewing/editing the program later it will look different!

LBL ¬TI
DECS
WSIZE 20
¬ F
PROMPT
STI 01
1000000
ENTERI
LDI 01
2
x
/
2
-
HEXS
RTN

Butterworth HPF/LPF Filter designer

LBL ¬BFIL
SF 00
¬MHZ ?
PROMPT
1 E6
*
STO 11
¬N
PROMPT
x<0?
CF 00
STO 10
XEQ 06
LBL 01
RCL 12
INT
XEQ 00
FS? 00
1/x
STO IND 12
ISG 12
GTO 01
¬COEFFICIENTS
FIX 3
STOP
ENG 3
XEQ 06
LBL 02
RCL 12
INT
RCL IND 12
RCL 11
2
*
PI
*
/
STO IND 12
ISG 12
GTO 02
XEQ 06
LBL 03
RCL 12
INT
2
/
FRC
FS? 00
GTO 09
GTO 10
LBL 09
¬HPF
x=0?
GTO 05
GTO 04
RTN
LBL 10
¬LPF
x=0?
GTO 04
GTO 05
RTN
LBL 04
RCL IND 12
50
*
STO IND 12
ISG 12
GTO 03
RTN
LBL 05
RCL IND 12
50
/
STO IND 12
ISG 12
GTO 03
RTN
LBL 06
RCL 10
ABS
1000
/
1
+
STO 12
RTN
LBL 00
2
*
1
-
180
*
RCL 10
ABS
2
*
/
SIN
2
*
RTN
END

XEQALPHABFILALPHA

MHZ ? 

5 R/S

N

Order/poles = N

Positive for HPF

Negative for LPF

5 pole LPF = -5

5CHSR/S

COEFFICIENTS
0.618

(at this point you can RCL 01 etc. up to RCL 05 to see the calculated Butterworth Coefficients)

• R01 : 0.618
• R02 : 1.618
• R03 : 2.000
• R04 : 1.618
• R05 : 0.618

R/S

LPF
393.5 -12

The calculated component values are now in Reg 01 - Reg 05

• R01 : 393.5pf
• R02 : 2.575uH
• R03 : 1.273nF
• R04 : 2.575uH
• R05 : 393.5pF

XEQALPHABFILALPHA

MHZ ? 

1 R/S

N

Order/poles = N

Positive for HPF

Negative for LPF

7 pole HPF = 7

7R/S

COEFFICIENTS
2.247

(at this point you can RCL 01 etc. up to RCL 07 to see the calculated Butterworth Coefficients)

• R01 : 2.247
• R02 : 0.802
• R03 : 0.555
• R04 : 0.500
• R05 : 0.555
• R06 : 0.802
• R07 : 2.247

R/S

HPF
17.88 -06

The calculated component values are now in Reg 01 - Reg 07

• R01 : 17.88uH
• R02 : 2.553nF
• R03 : 4.416uH
• R04 : 1.592nF
• R05 : 4.416uH
• R06 : 2.553nF
• R07 : 17.88uH

Page created Thu May 26 18:35:00 2022 by John Pumford-Green

Page last updated: 14/02/26 11:14 GMT

— John Pumford-Green 24/04/23 16:07