Programming volatile memory boards in older Icom Rigs and radio upgrades

[Radio Tech]

Hello all.
Some of the older Icom HF radios use a RAM board that holds the factory memory like the IC-745 and IC-751.  When the battery goes dead on these boards the factory program is lost and your radio becomes a brick.  The battery has a life of about 7 years but can be changed out. If not done correctly you lose the memory, again you end up with a brick.

A few folks have made a non volatile replacement board to solve this problem. Cost around 70 bucks US or so. Not bad no?

Anyway years ago I was able to read the memory out of one of these boards for the IC-745, This was by using the N2CBU DIY programmer.  This was a dos base programmer that using the parallel port on you old pc.  The programmer uses a CD4040, a 7805 regulator and a couple of caps.  It worked OK for reading the content of the ram. I never tried programming the unit.

What this is all about?
I am not the best when it comes to designing programmers. But I like to build something that is modern to work with today's computers.  I like to build a programmer that would be able to plug into a usb port, read the content of the ram then save it. And the ability to send the data back to the chip.

Perhaps someone with a bit more knowledge of modern programming can point me in the right direction. I am attaching the old files used to do this.

[martinator]

You can use something like the FM16W08 to replace your sram. You need to buy a soic28 to dip adapter to make programming easier,rearrange the address and data pins to match whichever application you have in mind and make a little circuit that pulses the chip enable after every address has been set up. Then you can read and write it like an eprom with a normal eprom programmer. I have also read out battery backed srams as eproms. You need to make adapters of course.You shouldn't need to build any special equipment, just buy a half decent eprom programmer.

[Radio Tech]

You can use something like the FM16W08 to replace your sram. You need to buy a soic28 to dip adapter to make programming easier,rearrange the address and data pins to match whichever application you have in mind and make a little circuit that pulses the chip enable after every address has been set up. Then you can read and write it like an eprom with a normal eprom programmer. I have also read out battery backed srams as eproms. You need to make adapters of course.You shouldn't need to build any special equipment, just buy a half decent eprom programmer.

From what I read is replacing the chip on the original board with a FM16W08?
That does not solve the problem. We still have to have a ram dump from the original chip. It cannot be removed from the board due to the memory is held there by the battery back up.  So still have to build the interface to read this memory.
If this is what you are saying. Remember, I am no programmer.

[German_EE]

From what I have found there are two different versions of this board. The old version uses a 1K x 8 SRAM together with a HD7432 IC but the new version uses a 2K x 8 SRAM and not much else. Are schematics of these RAM boards available because I have no idea what the HD7432 is doing?

As for reading the chip, apply 5V and ground to the right pins and monitor the four data lines. A binary counter or a set of eleven switches can be used to step through all 1024 addresses as you write them down. Before you start though you REALLY need to establish the function of pin 8 J17, is (WR) a write pin or write protect?

[AF6LJ]

Over on the Icom 745 Yahoo group someone published a memory dump of the contents of the ram chip. For those who don't know radios like the IC-745, 751, IC-R70 and a few others contain set up information in volital ram that is battery backed-up...
A couple of decades ago the folks over at PIEXX built and still market a replacement memory board that works in all these radios. One board that contains the microcode for all the Icom radios that used this module. https://www.piexx.com/?main_page=product_info&products_id=26

It should be possible to build an adapter that will allow the contents of the ram board to be dumped into one of those old school E-Prom programmers.
I have a couple of those RAM boards around here and it has been my experience the battery lasts for better than fifteen years.

[albert22]

Here:
https://www.qrz.ru/schemes/contribute/technology/icom751/english.shtml
you will find a diagram of the board, the programmer, and the binaries.
There are a couple of replacement boards that include a RAM and an EPROM. One made by PIEEX and another by IK2RND.
I didnt find any info on the memory map to differentiate what goes into the ram and what goes into the eprom.
Does anyone have the schematics for ram+eprom boards or info on how to manage the CS and address signals ?

Edit: while I was typing some posted similar data.

[Radio Tech]

From what I have found there are two different versions of this board. The old version uses a 1K x 8 SRAM together with a HD7432 IC but the new version uses a 2K x 8 SRAM and not much else. Are schematics of these RAM boards available because I have no idea what the HD7432 is doing?

As for reading the chip, apply 5V and ground to the right pins and monitor the four data lines. A binary counter or a set of eleven switches can be used to step through all 1024 addresses as you write them down. Before you start though you REALLY need to establish the function of pin 8 J17, is (WR) a write pin or write protect?

Yes they were the a board and b board.  I have several of these boards here in the shop that still work.
I never had problems doing this with DOS base computers in the 80's. When you get old the mind does not see things in this modern day in age.

Over on the Icom 745 Yahoo group someone published a memory dump of the contents of the ram chip. For those who don't know radios like the IC-745, 751, IC-R70 and a few others contain set up information in volital ram that is battery backed-up...
A couple of decades ago the folks over at PIEXX built and still market a replacement memory board that works in all these radios. One board that contains the microcode for all the Icom radios that used this module. https://www.piexx.com/?main_page=product_info&products_id=26

It should be possible to build an adapter that will allow the contents of the ram board to be dumped into one of those old school E-Prom programmers.
I have a couple of those RAM boards around here and it has been my experience the battery lasts for better than fifteen years.

I found a few dumps on the web over the past few moths for the 745 and 751. I still have my original dump I made years ago. 
I am looking at the information albert22 posted below now. This really should not be that hard to do. But I could be wrong.
Sue you have taught me a lot about the old 745 over the years.   

[Radio Tech]

Here:
https://www.qrz.ru/schemes/contribute/technology/icom751/english.shtml
you will find a diagram of the board, the programmer, and the binaries.
There are a couple of replacement boards that include a RAM and an EPROM. One made by PIEEX and another by IK2RND.
I didnt find any info on the memory map to differentiate what goes into the ram and what goes into the eprom.
Does anyone have the schematics for ram+eprom boards or info on how to manage the CS and address signals ?

Edit: while I was typing some posted similar data.

You are correct. I just installed one of each board in two different IC-745. Both boards work great. They both have a small problem and that is the foot print is not perfect on either.  Also the IK2RND board does not allow you to bolt it back to the main board. Minor issues yes.

I do remember seeing the information you posted a while back.  The programmer they used is also parallel port driven.  I do not think out of the 8 pc's I have running now any of them use a parallel port.  My new ones do not even have a serial. All usb.

I am going to look over some of the usb programmers on the market and see if there is a way to interface one to the ram unit.

[AF6LJ]

From what I have found there are two different versions of this board. The old version uses a 1K x 8 SRAM together with a HD7432 IC but the new version uses a 2K x 8 SRAM and not much else. Are schematics of these RAM boards available because I have no idea what the HD7432 is doing?

As for reading the chip, apply 5V and ground to the right pins and monitor the four data lines. A binary counter or a set of eleven switches can be used to step through all 1024 addresses as you write them down. Before you start though you REALLY need to establish the function of pin 8 J17, is (WR) a write pin or write protect?

Yes they were the a board and b board.  I have several of these boards here in the shop that still work.
I never had problems doing this with DOS base computers in the 80's. When you get old the mind does not see things in this modern day in age.

Over on the Icom 745 Yahoo group someone published a memory dump of the contents of the ram chip. For those who don't know radios like the IC-745, 751, IC-R70 and a few others contain set up information in volital ram that is battery backed-up...
A couple of decades ago the folks over at PIEXX built and still market a replacement memory board that works in all these radios. One board that contains the microcode for all the Icom radios that used this module. https://www.piexx.com/?main_page=product_info&products_id=26

It should be possible to build an adapter that will allow the contents of the ram board to be dumped into one of those old school E-Prom programmers.
I have a couple of those RAM boards around here and it has been my experience the battery lasts for better than fifteen years.

I found a few dumps on the web over the past few moths for the 745 and 751. I still have my original dump I made years ago. 
I am looking at the information albert22 posted below now. This really should not be that hard to do. But I could be wrong.
Sue you have taught me a lot about the old 745 over the years.   

I like my 745...
I am thinking you might be better off buying a parallel printer port card and using your old DOS program ether on a Linux box or a box running FreeDos.

Programming could also be done using the same adapter.
....
It wouldn't surprise me to find someone has already built and written up the software to program PROMS using the Linux operating system.

Oh on the AM mod...
I have hesitated doing that mod, I have felt there is an easier way to do the mod and get good high quality audio out of the radio.

[Radio Tech]

I like my 745...
I am thinking you might be better off buying a parallel printer port card and using your old DOS program ether on a Linux box or a box running FreeDos.

Programming could also be done using the same adapter.
....
It wouldn't surprise me to find someone has already built and written up the software to program PROMS using the Linux operating system.

Yes they are decent radios and good receivers.
Now that sparked an interest.  I had already thought about getting a card and plugging it in. but then I remember from way back that dos programs do not run that good (or at all) on today's computers. I have not thought about Linux and emulation. This could work.  May run by Best Buy this afternoon and pick one up. I do have a pc that is about mid 2000 that runs Linux. I am sure someone has already written it yes. I think you may just have hit the nail on the head Sue.   

Oh on the AM mod...
I have hesitated doing that mod, I have felt there is an easier way to do the mod and get good high quality audio out of the radio.

I agree, just looks like a lot of work to switch  it to transmit AM. Why would Icom do that? And they looked like it was done on a word processor from the 80's lol.
I guess I will give it a go just to see.
Thanks Sue.

[AF6LJ]

it will be interesting to see how your progress goes.

[Radio Tech]

it will be interesting to see how your progress goes.

I have forgotten all about Linux. I did a bit of reading this morning at 4am.  From what I have read Using Dosbox in Linux will emulate dos running at 386 speeds. I cannot find my old programmer so just going to build a new one.  Only need a CD4040 chip so will order a few of them today. This has me a bit excited.

I know the point of doing this is really mute, since you can buy to modern day replacements.  But how are we to know how long these folks will keep producing them? Plus old school is cool.  And just like to be able to program them for the fun of it.

[AF6LJ]

it will be interesting to see how your progress goes.

I have forgotten all about Linux. I did a bit of reading this morning at 4am.  From what I have read Using Dosbox in Linux will emulate dos running at 386 speeds. I cannot find my old programmer so just going to build a new one.  Only need a CD4040 chip so will order a few of them today. This has me a bit excited.

I know the point of doing this is really mute, since you can buy to modern day replacements.  But how are we to know how long these folks will keep producing them? Plus old school is cool.  And just like to be able to program them for the fun of it.

Good deal, sounds like you are well on the way.

[Co6aka]

From what I have read Using Dosbox in Linux will emulate dos running at 386 speeds.

You can configure the processor emulation and speed in the Dosbox config file, BUT the plain-vanilla Dosbox does not support the parallel port (unless something has recently changed) due to (infantile, IMHO) philosophical issues the developers have with old DOS games not needing parallel ports therefore Dosbox not having a need to support them. There are forks that do though, so you'll have to look for one that does.

And AFAIK the Winderz version should also work fine; you don't have to run Linux. (Disclaimer: I run Linux, not Winderz, so me-no-test-myself.)

Me-also-no-test, but you might be better off with QEMU plus FreeDOS on a machine with a parallel port.

[Radio Tech]

From what I have read Using Dosbox in Linux will emulate dos running at 386 speeds.

You can configure the processor emulation and speed in the Dosbox config file, BUT the plain-vanilla Dosbox does not support the parallel port (unless something has recently changed) due to (infantile, IMHO) philosophical issues the developers have with old DOS games not needing parallel ports therefore Dosbox not having a need to support them. There are forks that do though, so you'll have to look for one that does.

And AFAIK the Winderz version should also work fine; you don't have to run Linux. (Disclaimer: I run Linux, not Winderz, so me-no-test-myself.)

Me-also-no-test, but you might be better off with QEMU plus FreeDOS on a machine with a parallel port.

 
Oh well, we will have to try something else then.
Finding old computers that still work can be a chore.  Not giving up yet.  Going to ask some of my old Linux friends if they have anything.
Thanks for your time.

[Radio Tech]

Sue,
You ever heard of this?
I find it interesting but I do not see how this works.
See below...

USER 23 hours ago (edited)
start the IC745 with a known good RAM module. in the meantime, change the battery on the dead module. Now, remove the good RAM module from the transceiver, WHILE it's up and running. Put the dead RAM module in it, change the frequency a few times and the bands. Turn off the transceiver. Turn it back on, and the dead RAM module should be OK and programmed now.?
Reply  · 2
      
 ?
#148 More Icom IC 745 Repairs
 
The Radio Shop 2 hours ago
That is very interesting information.  Have you tried this? As you are the first person I ever seen mention this.  Details please.?
Reply  ·
      
 ?
 
USERi 1 hour ago
the CPU reads the data from the RAM at power on, and writes the data in the RAM when it's powering off, or band change, or frequency change. When you're swapping the RAM module, make sure you don't touch the VFO knob. I did this many times recovering swappable faulty computer BIOS-es. It's the same principle.?
Reply  ·

[AF6LJ]

Sue,
You ever heard of this?
I find it interesting but I do not see how this works.
See below...

USER 23 hours ago (edited)
start the IC745 with a known good RAM module. in the meantime, change the battery on the dead module. Now, remove the good RAM module from the transceiver, WHILE it's up and running. Put the dead RAM module in it, change the frequency a few times and the bands. Turn off the transceiver. Turn it back on, and the dead RAM module should be OK and programmed now.?
Reply  · 2
      
 ?
#148 More Icom IC 745 Repairs
 
The Radio Shop 2 hours ago
That is very interesting information.  Have you tried this? As you are the first person I ever seen mention this.  Details please.?
Reply  ·
      
 ?
 
USERi 1 hour ago
the CPU reads the data from the RAM at power on, and writes the data in the RAM when it's powering off, or band change, or frequency change. When you're swapping the RAM module, make sure you don't touch the VFO knob. I did this many times recovering swappable faulty computer BIOS-es. It's the same principle.?
Reply  ·

I haven't heard that before, but it is worth a try.
The author is banking on the CPU board writing all the band and mode data back to the RAM board.
Here is what we know...
1. Memory data is stored when memories are loaded with data.
2. The last band and mode we were on is stored on the RAM board.
3. The last modes and frequencies stored seen by the radio are also stored. .

I think it is worth a try...
Sadly the Icom IC-745 service manual doesn't have a detailed power up / power down description in the circuit theory section.

[Radio Tech]

I haven't heard that before, but it is worth a try.
The author is banking on the CPU board writing all the band and mode data back to the RAM board.
Here is what we know...
1. Memory data is stored when memories are loaded with data.
2. The last band and mode we were on is stored on the RAM board.
3. The last modes and frequencies stored seen by the radio are also stored. .

I think it is worth a try...
Sadly the Icom IC-745 service manual doesn't have a detailed power up / power down description in the circuit theory section.

First I ever heard of this before. And like you said he is seeing this from the way a computer works.
And from what we know from your 3 steps above he may be onto something.
I am curious that there is no boot strap or boot loader involved in this.  May be over thinking it a bit.

Well the good thing is I have 3 of the original ram boards here that work.  I an sacrifice one in the name of testing.  But before I do I want to break out the logic analyzer and look at the data being sent on turn on, vfo movement, mode change, and band change.  My logic device has 8 channels. Been wanting a good excuse to use it in some debugging.  This should solve our missing details from the SM as you mentioned.
Also if what he is saying then you could possible use a working ram board as a stand alone unit  to program a dead one.

This may get interesting.

Schematic below.

[AF6LJ]

I haven't heard that before, but it is worth a try.
The author is banking on the CPU board writing all the band and mode data back to the RAM board.
Here is what we know...
1. Memory data is stored when memories are loaded with data.
2. The last band and mode we were on is stored on the RAM board.
3. The last modes and frequencies stored seen by the radio are also stored. .

I think it is worth a try...
Sadly the Icom IC-745 service manual doesn't have a detailed power up / power down description in the circuit theory section.

First I ever heard of this before. And like you said he is seeing this from the way a computer works.
And from what we know from your 3 steps above he may be onto something.
I am curious that there is no boot strap or boot loader involved in this.  May be over thinking it a bit.

There is no need for a boot strap program, but there is the need to save some information regarding IF frequencies and such to make the display agree with where you are operating.
With that said and having spent time thinking about this, there is a large chance this won't work, but it is worth a try.
There is a slim chance the logic board writes data back to the ram module such as the first IF frequency (in Hex) If it reads it and for some unknown reason writes it back to the Ram Module you might be in luck, otherwise you will be building a programmer to load those modules after they have had the batteries replaced.

Well the good thing is I have 3 of the original ram boards here that work.  I an sacrifice one in the name of testing.  But before I do I want to break out the logic analyzer and look at the data being sent on turn on, vfo movement, mode change, and band change.  My logic device has 8 channels. Been wanting a good excuse to use it in some debugging.  This should solve our missing details from the SM as you mentioned.
Also if what he is saying then you could possible use a working ram board as a stand alone unit  to program a dead one.

This may get interesting.

Schematic below.

The service manual explains how data is loaded into the PLL board. The Matrix board is the glue logic that allows the Logic Board to talk to the front panel, along with a few other housekeeping bits of logic.

[AF6LJ]

One Other Thing...
The PIEXX module has jumpers for the various Icom radios that use this Ram Module, This implies the same module is used for all the radios and the jumpers on the PIEXX module are used to change the address range depending on which Icom you are using, ...
They load all the data for all the radios in the PIEXX module.

[Co6aka]

(O-Scope) Probe the "WP" pin of the RAM board while powering on and off and see what it's doing. The lower addresses of the RAM are normally write protected, which if I recall correctly is the purpose for the 7432. If "WP" is high then you can write to the lower addresses, and if it's low then you can't; normally it should be low. The interface ties "WP" high so the lower bytes can be written by the computer.

Also, the software SHOULD run on fast CPUs since it reads the hardware timer. The issue is whether or not the OS allows low-level hardware access to I/O ports. If you've got a classic LPT port that supports bidirectional transfers, and can boot DOS, give it a shot. To test without the RAM board, tie the DATA lines in a certain pattern, hex "A" perhaps, and see if you read all "A" and so on. If so, then you should be good to go with the RAM board.

[TheSteve]

This is a very interesting thread. I have an Icom 271H and a 471H - both use the battery backed ram module and have the original factory batteries installed still. A simple replacement that doesn't require the battery would be great.

[CJay]

I think, with a working RAM board and an empty one, it would be possible to make a piggyback adapter that allowed you to copy the contents of the good one to the bad one, no PC necessary.

Interested to know if there's a schematic of the board or at least a parts list (mainly just to know what the transistor is, I suspect a jellybean NPN type but...)

Would be a fun project to use something like a PIC or Arduino to replace the entire board, I think it would be easy enough to find a chip with enough NV storage that it could be a one chip solution.

[AF6LJ]

I think, with a working RAM board and an empty one, it would be possible to make a piggyback adapter that allowed you to copy the contents of the good one to the bad one, no PC necessary.

Interested to know if there's a schematic of the board or at least a parts list (mainly just to know what the transistor is, I suspect a jellybean NPN type but...)

Would be a fun project to use something like a PIC or Arduino to replace the entire board, I think it would be easy enough to find a chip with enough NV storage that it could be a one chip solution.

The idea of replacing the logic board with a modern microcontroller has crossed my mind
You could also replace the matrix board, which not only is in a bad place on the radio but overly complicates the process of reading switches off the front panel.
Remote control could be added.

I do like the idea of cloning a known good Ram board...

[CJay]

I think, with a working RAM board and an empty one, it would be possible to make a piggyback adapter that allowed you to copy the contents of the good one to the bad one, no PC necessary.

Interested to know if there's a schematic of the board or at least a parts list (mainly just to know what the transistor is, I suspect a jellybean NPN type but...)

Would be a fun project to use something like a PIC or Arduino to replace the entire board, I think it would be easy enough to find a chip with enough NV storage that it could be a one chip solution.

The idea of replacing the logic board with a modern microcontroller has crossed my mind
You could also replace the matrix board, which not only is in a bad place on the radio but overly complicates the process of reading switches off the front panel.
Remote control could be added.

I do like the idea of cloning a known good Ram board...

Cloning looks like it might be very simple, just jumper the data and address lines between boards, assert WR on the board to be written to and count through the address space with a simple binary counter?

Will attempt to reverse the board to a schematic and have a think later. Might be a little tricky as i've not got a board or indeed any of the radios the board comes from but it looks fairly simple, I assume the chip under the battery on the board with the larger SRAM is still a 7432?