From: [email protected] [mailto:[email protected]] On Behalf Of Doug W
Sent: Thursday, May 10, 2018 8:20 AM
To: [email protected]
Subject: [BITX20] an open message to those unhappy with the volume of messages #off_topic

?

Whenever I find something not returning the desired results I take that as a sign it is high time to read the fun manual.? Here are some tips I have gleaned to tame this tiger:

/g/BITX20/editsub allows you to select the frequency of email from this group with choices including never and once a day

Accessing the list from?/g/BITX20/topics allows you to read messages grouped by subject like a forum or message board

All incoming email from this list has [BITX20] in the subject.? Set up a rule/filter in your email client to skip your inbox and move messages to a separate folder for perusal at your leisure.

While not all messages use tags, many do.? You can also use your email client to sort tags that are not of interest to you

Lastly, be a good member of this community.? Use detailed subjects and tags so the group knows exactly what you are discussing or need help with.

-- There is nothing surprising in this. If they but knew it, almost all men in their degree, some time or other, cherish very nearly the same feelings towards the ocean with me.

From: [email protected] <[email protected]> On Behalf Of Doug W
Sent: Thursday, May 10, 2018 9:20 AM
To: [email protected]
Subject: [BITX20] an open message to those unhappy with the volume of messages #off_topic

?

Whenever I find something not returning the desired results I take that as a sign it is high time to read the fun manual.? Here are some tips I have gleaned to tame this tiger:

/g/BITX20/editsub allows you to select the frequency of email from this group with choices including never and once a day

Accessing the list from?/g/BITX20/topics allows you to read messages grouped by subject like a forum or message board

All incoming email from this list has [BITX20] in the subject.? Set up a rule/filter in your email client to skip your inbox and move messages to a separate folder for perusal at your leisure.

While not all messages use tags, many do.? You can also use your email client to sort tags that are not of interest to you

Lastly, be a good member of this community.? Use detailed subjects and tags so the group knows exactly what you are discussing or need help with.

-- There is nothing surprising in this. If they but knew it, almost all men in their degree, some time or other, cherish very nearly the same feelings towards the ocean with me.

From: [email protected] [mailto:[email protected]] On Behalf Of Lee
Sent: Wednesday, May 09, 2018 1:34 PM
To: [email protected]
Subject: Re: [BITX20] Removing solder resist.

?

I use a abrasive wheel on my dremel at a slow speed.? It is about the size of a nickel? and looks like rubber with fine abrasive dust molded in.?? I have even cut them in half and rubbed the trace by hand.?? Leaves nice clean shinny copper exposed.

Well, for starters, it's fun.
Got that in common with a uBitx.
Good enough for me.

More to the point, trying to get a uBitx to sit up and do stuff is a challenge
that brings to mind all the tricks we learned when programming these older machines.
Economy and elegance really counts when you have less than 1kbyte of memory to work with.?

Jerry


On Wed, May 9, 2018 at 08:25 pm, Robert Alexander wrote:

Just what does any of this have to do with the bitx or units radios.

?

Just what does any of this have to do with the bitx or units radios.

?

COSMAC ELF,? Built mine back '76.
12 switches, 1 push button, 2 hex digits of led, 256bytes of ram and the 1802, 8 pieces of CMOS logic.
I still pull it out to play.? Runs well on a battery of 8V or more.

Also National SC/MP (both I and II), Texas Inst 9900 in the form of the Technico starter board, 6800D1,
Kim1, TK80, Intersil 6100 Sampler (base PDP-8 in cmos), IMSAI IMP48 (intel8035), Intel SDK85 and
then memory fails me. There is a 6809 in there too.

My favorite is a 16 bitter made from TTL...? I decided I needed to understand how computers
worked at?the gate level. So design and build.? Not very fancy but proved I understood.? Killed
me wirewraping it too. The hard part was getting the carry logic right.? It was sorta PDP-8 /nova
in its origins.?Also proved that once you have a machine... programming happens, mostly by
need as it was unique.??

Allison

On May 9, 2018 at 8:08 PM Paul Wilson <paul@...> wrote:

I can beat that, 40 years ago I worked on a traffic signal controller based on an RCA COSMAC1802 processor. The board had 128 bytes of RAM.

Paul, VA6PW

On 09/05/2018 1:26 PM, Jack Purdum via Groups.Io wrote:

I was part of an NSF Grant to study "Microcomputers In Education" as taught by Larsen and Rony of Bugbook fame. Each of us was given a KIM-1 "microcomputer" as part of the course. It had an 6 digit 7-segment display with 256 BYTES of memory. (Later versions ballooned it to 1K!) Everything was written in 6800 assembler in octal!

Jack, W8TEE

On Wednesday, May 9, 2018, 1:32:29 PM EDT, Roy Appleton <twelveoclockhigh@...> wrote:

Mine was a SWTPC 6800 with 2k to 4k memory upgrade running the Motorola 6800 and MIKBUG ROM bootloader. Later spent another $600?for a 8k memory card to get me up to 12k so I could load a basic interpreter from audio tape with a 300 baud Kansas City "standard" cassette interface. Took 15 minutes from power on to prompt to get everything loaded! Still have it sitting in the attic!

Roy

WA0YMH

On Wed, May 9, 2018, 10:03 AM Jerry Gaffke via Groups.Io <jgaffke=[email protected]> wrote:

Like the PDP8 and Imsai 8080.
Back before EEPROM or fuse link ROM or Flash.

The alternative was to build enough memory by hand to boot the machine
using an array of diodes, a diode wherever you needed a zero bit.
But a row of switches on the front panel was cheaper, and the hourly rate for
an operator to flip switches every morning was pretty cheap too.
If the operator did it enough, they could key in the boot sequence from motor memory
while thinking about some coding problem to be tackled that day.

I had a friend who spent enough time around a PDP8 and ASR-33 that he could?
look at the holes in punched paper tape and know what was being said.

Jerry


On Wed, May 9, 2018 at 07:36 am, Jack Purdum wrote:

OMG! I built one of the Altair's for a friend and had to program it to test whether I had built it correctly. For those who don't know, those switches are for setting the binary bits for each byte of the program. When you had that byte set, you hit a "Deposit" switch which moved that byte into RAM. You could tell early Altair programmers by the "binary blisters" on their index finger!

Jack, W8TEE

?

From: [email protected] [mailto:[email protected]] On Behalf Of Jerry Gaffke via Groups.Io
Sent: Wednesday, May 9, 2018 7:33 PM
To: [email protected]
Subject: Re: [BITX20] SWR

?

Regarding that iterative algorithm to convert AD8307 ADC readings into voltsRF:

We only need two calibration constants stored, perhaps the nominal 0.025v/dB and 100vrms full scale.
It's the standard slope+intercept model.
Can be calibrated by taking two readings of two different known power levels into 50 ohms.

Can get by with as few as 2 integer bits for voltsADC (max of around 2.50),
so can have 30 fractional bits there since using 32 bit fixed point math.
(Complicates the flip to negative values when we have no sign bit, but easily do-able.)
The voltsRF could have as few as 7 integer bits if we assume a max of 128 volts rms there,
so 25 fractional bits.? I'm going for maximum fractional bits to minimize rounding errors
from that iterative processes, we can be plenty accurate in that regard.?
But this algorithm will not work with 16 bit fixed point on either voltsRF or voltsADC.

The first loop likely wants the ratio between iterations to be 31/32 rather than 1/2, this makes the
number of passes through the first loop be roughly the same as the passes through the second loop.
Ratio for the second loop can remain at 4097/4096.

Could add an extra loop or two, reducing iteration counts further, but I doubt that's necessary.?
I'll be very surprised if this takes more than a few milliseconds to complete.
Only executes during transmit when nothing much else is going on so doesn't really matter,
and we can check PTT within the loops and abort the computation when it goes away.

Flash usage should be quite minimal, best guess is maybe a couple hundred bytes.

A 10 bit ADC with 5v fullscale reading the AD8307 is marginal but might be useful.
Assuming we really have 10 bits, an LSB change represents? 5v/1024=0.00488v,
and given the 0.025v/dB slope of the AD8307 that's? 0.00488v/0.025 = 0.195 dB.
A power ratio of? ?10**(0.195/10) = 1.046.? So can measure power within 5% or so.

A much better choice would be a 12 bit ADC with a fullscale of 2.5v,
Power ratio for an LSB change is? ?10**(((2.5v/4096)/0.025)/10) = 1.0056,
So within better than 1% if we really have 12 bits.

Ok, I'm going to park this right here for now.?
But I am now convinced that reading a couple AD8307's?and then computing Watts
and SWR should be easy enough on the Nano,?and take up very little flash or RAM.?

Jerry, KE7ER


On Wed, May 9, 2018 at 10:20 am, Jerry Gaffke wrote:

# Those assumptions of? 0.025v, 100vrms, and 2.5v could be calibration

# constants stored in EEPROM for each individual AD8307.

?

?

# The final granularity of 1/4096 was chosen arbitrarily, increasing this?

# value makes it more accurate but increases the iterations required.

# Likewise, the initial granularity of 1/2 was also made arbitrarily.

# I have retained 6 significant digits in the voltsADC adjustment, equivalent?

# to about 18 fractional bits in the proposed 8:24 bit fixed point math.

?

# Those assumptions of? 0.025v, 100vrms, and 2.5v could be calibration

# constants stored in EEPROM for each individual AD8307.

?

?

# The final granularity of 1/4096 was chosen arbitrarily, increasing this?

# value makes it more accurate but increases the iterations required.

# Likewise, the initial granularity of 1/2 was also made arbitrarily.

# I have retained 6 significant digits in the voltsADC adjustment, equivalent?

# to about 18 fractional bits in the proposed 8:24 bit fixed point math.

?

On May 9, 2018 at 8:08 PM Paul Wilson <paul@...> wrote:

I can beat that, 40 years ago I worked on a traffic signal controller based on an RCA COSMAC1802 processor. The board had 128 bytes of RAM.

Paul, VA6PW

On 09/05/2018 1:26 PM, Jack Purdum via Groups.Io wrote:

I was part of an NSF Grant to study "Microcomputers In Education" as taught by Larsen and Rony of Bugbook fame. Each of us was given a KIM-1 "microcomputer" as part of the course. It had an 6 digit 7-segment display with 256 BYTES of memory. (Later versions ballooned it to 1K!) Everything was written in 6800 assembler in octal!

Jack, W8TEE

On Wednesday, May 9, 2018, 1:32:29 PM EDT, Roy Appleton <twelveoclockhigh@...> wrote:

Mine was a SWTPC 6800 with 2k to 4k memory upgrade running the Motorola 6800 and MIKBUG ROM bootloader. Later spent another $600?for a 8k memory card to get me up to 12k so I could load a basic interpreter from audio tape with a 300 baud Kansas City "standard" cassette interface. Took 15 minutes from power on to prompt to get everything loaded! Still have it sitting in the attic!

Roy

WA0YMH

On Wed, May 9, 2018, 10:03 AM Jerry Gaffke via Groups.Io <jgaffke=[email protected]> wrote:

Like the PDP8 and Imsai 8080.
Back before EEPROM or fuse link ROM or Flash.

The alternative was to build enough memory by hand to boot the machine
using an array of diodes, a diode wherever you needed a zero bit.
But a row of switches on the front panel was cheaper, and the hourly rate for
an operator to flip switches every morning was pretty cheap too.
If the operator did it enough, they could key in the boot sequence from motor memory
while thinking about some coding problem to be tackled that day.

I had a friend who spent enough time around a PDP8 and ASR-33 that he could?
look at the holes in punched paper tape and know what was being said.

Jerry


On Wed, May 9, 2018 at 07:36 am, Jack Purdum wrote:

OMG! I built one of the Altair's for a friend and had to program it to test whether I had built it correctly. For those who don't know, those switches are for setting the binary bits for each byte of the program. When you had that byte set, you hit a "Deposit" switch which moved that byte into RAM. You could tell early Altair programmers by the "binary blisters" on their index finger!

Jack, W8TEE

?

I was part of an NSF Grant to study "Microcomputers In Education" as taught by Larsen and Rony of Bugbook fame. Each of us was given a KIM-1 "microcomputer" as part of the course. It had an 6 digit 7-segment display with 256 BYTES of memory. (Later versions ballooned it to 1K!) Everything was written in 6800 assembler in octal!

Jack, W8TEE

On Wednesday, May 9, 2018, 1:32:29 PM EDT, Roy Appleton <twelveoclockhigh@...> wrote:

Mine was a SWTPC 6800 with 2k to 4k memory upgrade running the Motorola 6800 and MIKBUG ROM bootloader. Later spent another $600?for a 8k memory card to get me up to 12k so I could load a basic interpreter from audio tape with a 300 baud Kansas City "standard" cassette interface. Took 15 minutes from power on to prompt to get everything loaded! Still have it sitting in the attic!

Roy

WA0YMH

On Wed, May 9, 2018, 10:03 AM Jerry Gaffke via Groups.Io <jgaffke=[email protected]> wrote:

Like the PDP8 and Imsai 8080.
Back before EEPROM or fuse link ROM or Flash.

The alternative was to build enough memory by hand to boot the machine
using an array of diodes, a diode wherever you needed a zero bit.
But a row of switches on the front panel was cheaper, and the hourly rate for
an operator to flip switches every morning was pretty cheap too.
If the operator did it enough, they could key in the boot sequence from motor memory
while thinking about some coding problem to be tackled that day.

I had a friend who spent enough time around a PDP8 and ASR-33 that he could?
look at the holes in punched paper tape and know what was being said.

Jerry


On Wed, May 9, 2018 at 07:36 am, Jack Purdum wrote:

OMG! I built one of the Altair's for a friend and had to program it to test whether I had built it correctly. For those who don't know, those switches are for setting the binary bits for each byte of the program. When you had that byte set, you hit a "Deposit" switch which moved that byte into RAM. You could tell early Altair programmers by the "binary blisters" on their index finger!

Jack, W8TEE

Whatever crazy pattern, it will still just be a random scattering of readings, dependent
on where the audio peaks and troughs are.
Averaging helps.
An easy way to average those RF voltage detectors may be to just make the caps bigger.

On Wed, May 9, 2018 at 03:58 pm, Glenn wrote:

I'm not? a programmer but what if you sample the forward and reverse and then alternate a few times ie reverse and forward, forward and reverse, and average the result.? I imagine this should remove or at least minimise the time difference effects.

?

Hi

I'm not? a programmer but what if you sample the forward and reverse and then alternate a few times ie reverse and forward, forward and reverse, and average the result.? I imagine this should remove or at least minimise the time difference effects.

glenn

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