Conversion Confusion!
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Posts: 46,084
I am now deep into serial communication formatter issues and I am
lost as usual! here is my question
I have a variable value I receive from one serial device that I want
to convert into hex and then send it to another device. Here is how
I want it to work:
inData var byte
outData var byte
SerIn deviceIn,baude,[noparse][[/noparse]dec2 dataIN] 'incoming value ranges up to 99
dataOut = the hex value of dataIn ' not sure how to do that
serOut deviceOut,baud,[noparse][[/noparse]dataOut] ' the reciever expect string
like "2F" which works fine from Hyperterminal
I would like to know :
1- how to convert a variable from decimal to HEX?
2- which modifier to use (Hex or Dec) when sending a dataOut which
is in hex now?
Hope to hear from you.
Al
lost as usual! here is my question
I have a variable value I receive from one serial device that I want
to convert into hex and then send it to another device. Here is how
I want it to work:
inData var byte
outData var byte
SerIn deviceIn,baude,[noparse][[/noparse]dec2 dataIN] 'incoming value ranges up to 99
dataOut = the hex value of dataIn ' not sure how to do that
serOut deviceOut,baud,[noparse][[/noparse]dataOut] ' the reciever expect string
like "2F" which works fine from Hyperterminal
I would like to know :
1- how to convert a variable from decimal to HEX?
2- which modifier to use (Hex or Dec) when sending a dataOut which
is in hex now?
Hope to hear from you.
Al
Comments
(indicated by leading $) and binary (indicated by leading %). When doing
conversions from and to serial streams, the following formatters are used:
DEC, HEX and BIN.
1) You can't change the internal representation of a variable, just how it
gets presented to the world.
2) Use the HEX modifier (some version of it) to send a variable to a serial
data stream in the hexadecimal format. For example:
SEROUT pin, baud, [noparse][[/noparse]HEX2 someVar]
BTW ... this stuff is pretty thoroughly covered in our manual that can be
downloaded free of charge.
-- Jon Williams
-- Parallax
In a message dated 1/12/2003 4:07:22 PM Central Standard Time,
brownstamp@y... writes:
> I am now deep into serial communication formatter issues and I am
> lost as usual! here is my question
>
> I have a variable value I receive from one serial device that I want
> to convert into hex and then send it to another device. Here is how
> I want it to work:
>
> inData var byte
> outData var byte
>
> SerIn deviceIn,baude,[noparse][[/noparse]dec2 dataIN] 'incoming value ranges up to 99
>
> dataOut = the hex value of dataIn ' not sure how to do that
>
> serOut deviceOut,baud,[noparse][[/noparse]dataOut] ' the reciever expect string
> like "2F" which works fine from Hyperterminal
>
> I would like to know :
> 1- how to convert a variable from decimal to HEX?
> 2- which modifier to use (Hex or Dec) when sending a dataOut which
> is in hex now?
>
> Hope to hear from you.
[noparse][[/noparse]Non-text portions of this message have been removed]
In a previous thread with Tracy (By the way thanks for the help Tracy, your
BCD explanation was stunning), she explained that when talking to the
DS1302, it uses BCD, using the $ modifier.
eg. hours =$15 (3 PM)
I have come up with a somewhat cumbersome code solution converting decimal
to bcd, but just don't know how to do it properly (my solution is somewhat
lengthy)
Problem goes something like this (shortened):-
' get decimal time data from another stamp
serin [noparse][[/noparse]hours]
serin [noparse][[/noparse]days]
serin [noparse][[/noparse]minutes]
'*****convert variables containing decimal to bcd here**
'set the ds1302
shiftout [noparse][[/noparse]hours]
shiftout [noparse][[/noparse]days]
shiftout [noparse][[/noparse]minutes]
Can you help me at all please?
Regards,
Dwain.
Original Message
From: <jonwms@a...>
To: <basicstamps@yahoogroups.com>
Sent: Monday, January 13, 2003 9:28 AM
Subject: Re: [noparse][[/noparse]basicstamps] Conversion Confusion!
> The BASIC Stamp "knows" three numeric systems: decimal (default),
hexadecimal
> (indicated by leading $) and binary (indicated by leading %). When doing
> conversions from and to serial streams, the following formatters are used:
> DEC, HEX and BIN.
>
> 1) You can't change the internal representation of a variable, just how it
> gets presented to the world.
>
> 2) Use the HEX modifier (some version of it) to send a variable to a
serial
> data stream in the hexadecimal format. For example:
>
> SEROUT pin, baud, [noparse][[/noparse]HEX2 someVar]
>
>
> BTW ... this stuff is pretty thoroughly covered in our manual that can be
> downloaded free of charge.
>
> -- Jon Williams
> -- Parallax
>
>
> In a message dated 1/12/2003 4:07:22 PM Central Standard Time,
> brownstamp@y... writes:
>
> > I am now deep into serial communication formatter issues and I am
> > lost as usual! here is my question
> >
> > I have a variable value I receive from one serial device that I want
> > to convert into hex and then send it to another device. Here is how
> > I want it to work:
> >
> > inData var byte
> > outData var byte
> >
> > SerIn deviceIn,baude,[noparse][[/noparse]dec2 dataIN] 'incoming value ranges up to 99
> >
> > dataOut = the hex value of dataIn ' not sure how to do that
> >
> > serOut deviceOut,baud,[noparse][[/noparse]dataOut] ' the reciever expect string
> > like "2F" which works fine from Hyperterminal
> >
> > I would like to know :
> > 1- how to convert a variable from decimal to HEX?
> > 2- which modifier to use (Hex or Dec) when sending a dataOut which
> > is in hex now?
> >
> > Hope to hear from you.
>
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>
>
dwainsworld@e... writes:
> In a previous thread with Tracy (By the way thanks for the help Tracy, your
> BCD explanation was stunning), she explained that when talking to the
> DS1302, it uses BCD, using the $ modifier.
>
>
Tracy is a he. Boy, wait until the Women's Network hears about this!!!
Sid
[noparse][[/noparse]Non-text portions of this message have been removed]
>serin [noparse][[/noparse]hours]
>serin [noparse][[/noparse]days]
>serin [noparse][[/noparse]minutes]
>
>'*****convert variables containing decimal to bcd here**
hours = hours/10 * 16 + (hours//10)
days = days/10*16+(days//10)
minutes = minutes/10*16+(minutes//10)
' example: hours = 23 in decimal
' 23/10 = 2 integer arithmetic, drop the remainder
' 23/10*16 = 32 or in hex, $20
' 23//10=3 is the remainder that was dropped, ones digit
' 23/10*16+(23//10) = 35 in decimal, but $23 in BCD!!!
' that is what you need to set the clock to "23"
>
>'set the ds1302
>shiftout [noparse][[/noparse]hours]
>shiftout [noparse][[/noparse]days]
>shiftout [noparse][[/noparse]minutes]
Sid, my wife's name is Teri, so we are always confused around here,
but the Women's Network has nothing to do with it!
-- regards,
Tracy Allen .
electronically monitored ecosystems
mailto:tracy@e...
http://www.emesystems.com
Bwahaha
Original Message
From: "Tracy Allen" <tracy@e...>
To: <basicstamps@yahoogroups.com>
Sent: Sunday, January 12, 2003 4:50 PM
Subject: Re: [noparse][[/noparse]basicstamps] Conversion Confusion!
> >' get decimal time data from another stamp
> >serin [noparse][[/noparse]hours]
> >serin [noparse][[/noparse]days]
> >serin [noparse][[/noparse]minutes]
> >
> >'*****convert variables containing decimal to bcd here**
>
> hours = hours/10 * 16 + (hours//10)
> days = days/10*16+(days//10)
> minutes = minutes/10*16+(minutes//10)
>
> ' example: hours = 23 in decimal
> ' 23/10 = 2 integer arithmetic, drop the remainder
> ' 23/10*16 = 32 or in hex, $20
> ' 23//10=3 is the remainder that was dropped, ones digit
> ' 23/10*16+(23//10) = 35 in decimal, but $23 in BCD!!!
> ' that is what you need to set the clock to "23"
>
> >
> >'set the ds1302
> >shiftout [noparse][[/noparse]hours]
> >shiftout [noparse][[/noparse]days]
> >shiftout [noparse][[/noparse]minutes]
>
>
> Sid, my wife's name is Teri, so we are always confused around here,
> but the Women's Network has nothing to do with it!
>
> -- regards,
> Tracy Allen .
> electronically monitored ecosystems
> mailto:tracy@e...
> http://www.emesystems.com
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
full beard is actually a guy ?
http://www.emesys.com/EMEmore.htm
--- In basicstamps@yahoogroups.com, Newzed@a... wrote:
> In a message dated 01/12/2003 19:14:15 Eastern Standard Time,
> dwainsworld@e... writes:
>
>
> > In a previous thread with Tracy (By the way thanks for the help
Tracy, your
> > BCD explanation was stunning), she explained that when talking to
the
> > DS1302, it uses BCD, using the $ modifier.
> >
> >
>
> Tracy is a he. Boy, wait until the Women's Network hears about
this!!!
>
> Sid
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
Sure, I'm happy to help ... and I still think that spending some time with
the manual will do you some good.
Okay, you present a different request than last time. There is a difference
between straight decimal format and BCD (binary coded decimal). BCD numbers
(one byte) contain the tens digit (0 - 9) in their high nibble, the ones
digit in the low-nibble.
Assuming you can get your decimal numbers, you can convert to BCD like this:
bcdHours = (hours / 10 << 4) + (hours // 10)
Of course, you can use the same variable, but you'll have to keep track of
what format it currently holds.
Try this to see what I mean:
hours = 13
DEBUG DEC2 hours, CR
hours = (hours / 10 << 4) + (hours // 10)
DEBUG DEC2 hours, CR
DEBUG HEX2 hours, CR
Your output will be:
13
19
13
I'll leave it to you to figure out why. It will be a good learning tool.
The hex indicator ($) or modifier (HEX) works becase hex numbers are similar
to BCD in that each nibble is used to hold one digit -- the difference being
that valid HEX digits are 0 - 9, A - F.
-- Jon Williams
-- Parallax
In a message dated 1/12/2003 6:13:56 PM Central Standard Time,
dwainsworld@e... writes:
> I too am still in the conversion confusion stage John!
>
> In a previous thread with Tracy (By the way thanks for the help Tracy, your
> BCD explanation was stunning), she explained that when talking to the
> DS1302, it uses BCD, using the $ modifier.
>
> eg. hours =$15 (3 PM)
>
> I have come up with a somewhat cumbersome code solution converting decimal
> to bcd, but just don't know how to do it properly (my solution is somewhat
> lengthy)
>
> Problem goes something like this (shortened):-
>
>
> ' get decimal time data from another stamp
> serin [noparse][[/noparse]hours]
> serin [noparse][[/noparse]days]
> serin [noparse][[/noparse]minutes]
>
> '*****convert variables containing decimal to bcd here**
>
> 'set the ds1302
> shiftout [noparse][[/noparse]hours]
> shiftout [noparse][[/noparse]days]
> shiftout [noparse][[/noparse]minutes]
>
> Can you help me at all please?
>
> Regards,
>
> Dwain.
[noparse][[/noparse]Non-text portions of this message have been removed]
Original Message
From: <Newzed@a...>
To: <basicstamps@yahoogroups.com>
Sent: Monday, January 13, 2003 11:19 AM
Subject: Re: [noparse][[/noparse]basicstamps] Conversion Confusion!
> In a message dated 01/12/2003 19:14:15 Eastern Standard Time,
> dwainsworld@e... writes:
>
>
> > In a previous thread with Tracy (By the way thanks for the help Tracy,
your
> > BCD explanation was stunning), she explained that when talking to the
> > DS1302, it uses BCD, using the $ modifier.
> >
> >
>
> Tracy is a he. Boy, wait until the Women's Network hears about this!!!
>
> Sid
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>
>
Original Message
From: <davemucha@j...>
To: <basicstamps@yahoogroups.com>
Sent: Monday, January 13, 2003 12:44 PM
Subject: [noparse][[/noparse]basicstamps] Re: Conversion Confusion!
> You mean Dr. Thomas Tracy Allen, the woman in the red life jacket and
> full beard is actually a guy ?
>
> http://www.emesys.com/EMEmore.htm
>
>
>
>
>
> --- In basicstamps@yahoogroups.com, Newzed@a... wrote:
> > In a message dated 01/12/2003 19:14:15 Eastern Standard Time,
> > dwainsworld@e... writes:
> >
> >
> > > In a previous thread with Tracy (By the way thanks for the help
> Tracy, your
> > > BCD explanation was stunning), she explained that when talking to
> the
> > > DS1302, it uses BCD, using the $ modifier.
> > >
> > >
> >
> > Tracy is a he. Boy, wait until the Women's Network hears about
> this!!!
> >
> > Sid
> >
> >
> > [noparse][[/noparse]Non-text portions of this message have been removed]
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>
>
as well. I know that I ask a lot of dumb questions, but maths just aint my
forte im afraid. (Beer is!!)
Regards,
Dwain.
Original Message
From: <jonwms@a...>
To: <basicstamps@yahoogroups.com>
Sent: Monday, January 13, 2003 12:56 PM
Subject: Re: [noparse][[/noparse]basicstamps] Conversion Confusion!
> Dwain:
>
> Sure, I'm happy to help ... and I still think that spending some time with
> the manual will do you some good.
>
> Okay, you present a different request than last time. There is a
difference
> between straight decimal format and BCD (binary coded decimal). BCD
numbers
> (one byte) contain the tens digit (0 - 9) in their high nibble, the ones
> digit in the low-nibble.
>
> Assuming you can get your decimal numbers, you can convert to BCD like
this:
>
> bcdHours = (hours / 10 << 4) + (hours // 10)
>
> Of course, you can use the same variable, but you'll have to keep track of
> what format it currently holds.
>
> Try this to see what I mean:
>
> hours = 13
> DEBUG DEC2 hours, CR
> hours = (hours / 10 << 4) + (hours // 10)
> DEBUG DEC2 hours, CR
> DEBUG HEX2 hours, CR
>
> Your output will be:
>
> 13
> 19
> 13
>
> I'll leave it to you to figure out why. It will be a good learning tool.
>
> The hex indicator ($) or modifier (HEX) works becase hex numbers are
similar
> to BCD in that each nibble is used to hold one digit -- the difference
being
> that valid HEX digits are 0 - 9, A - F.
>
> -- Jon Williams
> -- Parallax
>
>
> In a message dated 1/12/2003 6:13:56 PM Central Standard Time,
> dwainsworld@e... writes:
>
> > I too am still in the conversion confusion stage John!
> >
> > In a previous thread with Tracy (By the way thanks for the help Tracy,
your
> > BCD explanation was stunning), she explained that when talking to the
> > DS1302, it uses BCD, using the $ modifier.
> >
> > eg. hours =$15 (3 PM)
> >
> > I have come up with a somewhat cumbersome code solution converting
decimal
> > to bcd, but just don't know how to do it properly (my solution is
somewhat
> > lengthy)
> >
> > Problem goes something like this (shortened):-
> >
> >
> > ' get decimal time data from another stamp
> > serin [noparse][[/noparse]hours]
> > serin [noparse][[/noparse]days]
> > serin [noparse][[/noparse]minutes]
> >
> > '*****convert variables containing decimal to bcd here**
> >
> > 'set the ds1302
> > shiftout [noparse][[/noparse]hours]
> > shiftout [noparse][[/noparse]days]
> > shiftout [noparse][[/noparse]minutes]
> >
> > Can you help me at all please?
> >
> > Regards,
> >
> > Dwain.
>
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>
>
>Okay, you present a different request than last time. There is a difference
>between straight decimal format and BCD (binary coded decimal). BCD numbers
>(one byte) contain the tens digit (0 - 9) in their high nibble, the ones
>digit in the low-nibble.
Jon - could you clear up a potential area of confusion, please? My
understanding is that a BCD number contains only 1 digit in the byte (in
the low nibble). The upper nibble is clear. Packed BCD places 2 BCD
digits in the byte (1 digit in each nibble).
What you have described above is packed BCD.
Is this a Stamps thing?
dwayne
--
Dwayne Reid <dwayner@p...>
Trinity Electronics Systems Ltd Edmonton, AB, CANADA
(780) 489-3199 voice (780) 487-6397 fax
Celebrating 18 years of Engineering Innovation (1984 - 2002)
.-. .-. .-. .-. .-. .-. .-. .-. .-. .-
`-' `-' `-' `-' `-' `-' `-' `-' `-'
Do NOT send unsolicited commercial email to this email address.
This message neither grants consent to receive unsolicited
commercial email nor is intended to solicit commercial email.
NOW THE NAMEOLOGY IS REALLY GETTING HARD!!
Original Message
From: "Dwayne Reid" <dwayner@p...>
To: <basicstamps@yahoogroups.com>
Sent: Monday, January 13, 2003 3:03 PM
Subject: Re: [noparse][[/noparse]basicstamps] Conversion Confusion!
> At 08:56 PM 1/12/03 -0500, jonwms@a... wrote:
>
> >Okay, you present a different request than last time. There is a
difference
> >between straight decimal format and BCD (binary coded decimal). BCD
numbers
> >(one byte) contain the tens digit (0 - 9) in their high nibble, the ones
> >digit in the low-nibble.
>
> Jon - could you clear up a potential area of confusion, please? My
> understanding is that a BCD number contains only 1 digit in the byte (in
> the low nibble). The upper nibble is clear. Packed BCD places 2 BCD
> digits in the byte (1 digit in each nibble).
>
> What you have described above is packed BCD.
>
> Is this a Stamps thing?
>
> dwayne
>
> --
> Dwayne Reid <dwayner@p...>
> Trinity Electronics Systems Ltd Edmonton, AB, CANADA
> (780) 489-3199 voice (780) 487-6397 fax
>
> Celebrating 18 years of Engineering Innovation (1984 - 2002)
> .-. .-. .-. .-. .-. .-. .-. .-. .-. .-
> `-' `-' `-' `-' `-' `-' `-' `-' `-'
> Do NOT send unsolicited commercial email to this email address.
> This message neither grants consent to receive unsolicited
> commercial email nor is intended to solicit commercial email.
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>
>
BCD." So I did a bit of research on the Net and found that the accepted
definition of BCD as "represents each of the digits of an unsigned decimal as
the 4-bit binary equivalents" and Packed BCD as "packs two decimal digits
into a single byte."
I've been speaking very generically (a decimal digit held in a nibble) and
your questions always involved bytes and two-digit values. Perhaps it's me
that is confused, but the technical information I gave you was sound.
-- Jon Williams
-- Parallax
In a message dated 1/12/2003 10:41:32 PM Central Standard Time,
dwayner@p... writes:
> Jon - could you clear up a potential area of confusion, please? My
> understanding is that a BCD number contains only 1 digit in the byte (in
> the low nibble). The upper nibble is clear. Packed BCD places 2 BCD
> digits in the byte (1 digit in each nibble).
>
> What you have described above is packed BCD.
>
> Is this a Stamps thing?
>
> dwayne
>
[noparse][[/noparse]Non-text portions of this message have been removed]
For me, the learning process has involved something like this:-
1 See Basic Stamp in Catalogue, maybe I should get one, but it's a bit
expensive in AUS$, and besides that does it really do what it looks like it
does?
2 Got One a year later with a project in mind, still not sure it can do it
3 Skim read manual in a few days, remembering some basic from Commodore64
basic and Z80 days when computers were interesting but lacked purpose
besides an interesting chess game
4 Mess with BS2 until I can get a fuel computer for my boat to roughly
work, I need more program space.
5 Drink Beer (home brew of course)
6 Have ideas for a thousand projects that need micro controlling that just
haven't been done before, or have already been done but are still wayyyyy to
expensive and can be done cheaper.
7 Make some of those idea work
8 Learn how to do stuff to make other ideas work as the need arises.
This group is just damn great for item No. 8. I can often read the manual
and not glean what I want, but the odd question here gets explained in a way
that I can understand.
Keep up the good work.
regards,
Dwain
Original Message
From: <jonwms@a...>
To: <basicstamps@yahoogroups.com>
Sent: Tuesday, January 14, 2003 12:09 AM
Subject: Re: [noparse][[/noparse]basicstamps] Conversion Confusion!
> Maybe it's just my ignorance -- I've never heard or used the term "packed
> BCD." So I did a bit of research on the Net and found that the accepted
> definition of BCD as "represents each of the digits of an unsigned decimal
as
> the 4-bit binary equivalents" and Packed BCD as "packs two decimal digits
> into a single byte."
>
> I've been speaking very generically (a decimal digit held in a nibble) and
> your questions always involved bytes and two-digit values. Perhaps it's
me
> that is confused, but the technical information I gave you was sound.
>
> -- Jon Williams
> -- Parallax
>
>
> In a message dated 1/12/2003 10:41:32 PM Central Standard Time,
> dwayner@p... writes:
>
> > Jon - could you clear up a potential area of confusion, please? My
> > understanding is that a BCD number contains only 1 digit in the byte (in
> > the low nibble). The upper nibble is clear. Packed BCD places 2 BCD
> > digits in the byte (1 digit in each nibble).
> >
> > What you have described above is packed BCD.
> >
> > Is this a Stamps thing?
> >
> > dwayne
> >
>
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>
>
download. If you've got a slow internet connection ... well, what a great
excuse to pop open another beer!
Try these links:
<A
HREF="http://www.parallax.com/html_pages/resources/nvcolumns/Nuts_Volts_Download\
s.asp">
http://www.parallax.com/html_pages/resources/nvcolumns/Nuts_Volts_Downloads.asp
</A>
<A
HREF="http://www.parallax.com/html_pages/edu/curriculum/sic_curriculum.asp">http\
<A
HREF="http://www.parallax.com/html_pages/robotics/books/robo_books.asp">http://w\
ww.parallax.com/html_pages/robotics/books/robo_books.asp</A>
-- Jon Williams
-- Parallax
In a message dated 1/13/2003 7:35:15 AM Central Standard Time,
dwainsworld@e... writes:
> This group is just damn great for item No. 8. I can often read the manual
> and not glean what I want, but the odd question here gets explained in a
> way
> that I can understand.
>
[noparse][[/noparse]Non-text portions of this message have been removed]
assembly. I vaguely remember having a hard time grasping the concept.
Original Message
> Maybe it's just my ignorance -- I've never heard or used the term "packed
> BCD." So I did a bit of research on the Net and found that the accepted
> definition of BCD as "represents each of the digits of an unsigned decimal
as
> the 4-bit binary equivalents" and Packed BCD as "packs two decimal digits
> into a single byte."
>
> I've been speaking very generically (a decimal digit held in a nibble) and
> your questions always involved bytes and two-digit values. Perhaps it's
me
> that is confused, but the technical information I gave you was sound.
> I think the packed decimal comes from the old IBM 360/370 mainframe
> assembly. I vaguely remember having a hard time grasping the concept.
IBM's packed decimal was a piece of cake to read in a dump -
each 4-bit nibble represents 1 decimal digit (0-9) with a sign
indicator in the last nibble of either 0xF for possitive or 0xC
for negative, all right justified with a leading 0x0 nibble if
required to pad out to a full byte.
Now, IBM's own floating point format (before IEEE 754).... THAT
was confussion!