Saturday, November 22, 2014

Heathkit RX-1 Recapping

I finished "recapping", i.e. replacing the paper capacitors in the Heathkit RX-1. Some were a little tricky to get at when the unit was assembled.

Here are some of the original caps:



And here is an image after recapping (the news ones are all yellow):



I didn't notice any significant difference after recapping, but it is still a good idea to do. Depending on the circuit location, a leaky capacitor can damage a tube or other expensive component. Below is all the old caps after removal:


Wednesday, November 19, 2014

Heathkit RX-1 Restoration

My latest restoration project is a Heathkit RX-1 "Mohawk" Amateur Radio Receiver.


I've created YouTube video that describes it. This was Heathkit's high end amateur radio receiver of the time, with all the bells and whistles of a radio of the time. It's a large beast, weighing in at about 50 pounds.

It works, but I'm currently in the process or recapping it, to make sure that it is fully functional. I'm replacing all of the wax paper capacitors with new ones, as the original ones tend to become electrically leaky over time. This may fix the operation of the notch filter, which doesn't seem to be fully working. The circuitry around the notch filter uses a lot of paper caps.

Once that is done I will run through the alignment procedure again. As it is quite an involved procedure, that might be suitable for another YouTube video of its own.

Thursday, October 23, 2014

The Visible Monitor

While waiting for my Briel Superboard III kit, I was reminded of a book that I blogged about last year. The Visible Monitor program in that book was written to run on a number of computers of the era, including the Ohio Scientific C-1P or Superboard II.


In preparation for trying it on the Superboard III, I entered the machine code from the book. Back in the day, this consisted of typing in many numbers as BASIC DATA statements. A loader program read the data at run-time and stored it in memory. A simple checksum scheme caught most errors. After a number of sessions I had all the code entered. I was able to save some time by scanning the book pages and using OCR software to convert it to text, however the process was still quite error prone and required a lot of manual corrections.

After fixing any obvious errors, I was able to load the software on an Ohio Scientific computer emulator. The loader program found a number of additional errors that I had made. After correcting those, I made a file suitable for directly loading from the OSI monitor program. Loading it into the emulator, I was pleasantly surprised to see that it ran fine. I'm quite confident that it will also run on the real hardware.

I also entered some of the source code for the monitor with suitable changes to build with the CC65 assembler. I've only entered a small portion of the code so far, and may not complete this as it is a very time consuming task. All of the code can be found here at github.

By coincidence, a lot of vintage books I recently bought on eBay included the book "Top Down Assembly Language Programming for your VIC-20 and Commodore 64". It turns out that this is essentially the same book, but with the Visible Monitor ported to the VIC-20 and Commodore 64 computers.


To be honest, the Visible Monitor seems a little clunky and hard to use and I think my JMON program is better. I plan to port it to the Superboard III.

Thursday, September 4, 2014

Zenith H500 Super Trans-Oceanic

The Zenith Trans-Oceanics were an extremely popular (although expensive) series of shortwave portable radios made by Zenith from the 1940s through 1980s. I own a model H500, the most popular model of the series. Although I restored it almost 10 years ago, I finally got around to making a YouTube video about it.

On the Heathkit front, I just received two more pieces of test equipment that I will be restoring, an IG-18 Sine-Square Audio Generator and an IM-1212 Digital Multimeter. I plan to make YouTube videos about these units as well.


Thursday, August 21, 2014

Ohio Scientific Superboard II

The first computer I owned was an Ohio Scientific Superboard II. Bought in 1980, it was the only reasonably complete computer on the market for under $300.

I learned a lot on that machine, including BASIC and 6502 machine and assembly language programming.

Alas, it was damaged in a flood a number of years ago and had to be thrown out. I recently found this original paperwork which came with the machine:





I am, however, eagerly waiting the Superboard III.  a replica of the Superboard II that is being offered by Briel Computers. It should be fun to see the Superboard powered up again, running BASIC and the really primitive machine language monitor. I might even have some software I wrote on old cassette tapes that can still be recovered.

I'll report back here as the project progresses.

Thursday, July 31, 2014

Quick Hack: A Soldering Ventilation Fan

Here is a quick solution I put together earlier this week. The fumes from solder (more so the flux rather than lead) are not particularly healthy to breathe. I usually solder in a room with decent ventilation but I was meaning to set up some kind of fan. My quick solution was to take a small muffin fan from my junk box, glue it to a heavy block of marble I had (from some old trophies) and extend the wires to go to a bench power supply. Sitting this unit next to the soldering iron or PCB will keep the fumes away while I am hunched over a board during soldering. It only took about five minutes to throw together from junk parts I had lying around.



Thursday, July 24, 2014

Can Heathkit Make a Comeback? Yes, and Here's 10 Reasons Why.

Despite all the reasons I listed in my last blog post on why Heathkit could not successfully reenter the kit business today, I believe they still can. Here are some reasons why, and how, they could do it.

1. Reinvent yourself. Heathkit started as an airplane manufacturer, then got into aviation electronics. Then test equipment, amateur radio, audio, and computers. The company twice lost their president in airplane crashes and had to reinvent itself. The new Heathkit could and probably should be different from the Heathkit during the heyday of the past. There are many opportunities for products different from those that Heathkit traditionally offered. They need to think outside the box and come up with new ideas for product opportunities.

2. Leverage the Internet. The Internet means there is no longer a need for brick and mortar stores. No printed catalogues or advertising. The Internet means global markets. To be successful, Heathkit needs to adapt to the times. As just one example, the large effort to write assembly manuals could be crowdsourced by allowing users to edit and improve the manuals, much like Wikipedia. Support for building kits could be handled by on-line forums. People who are active in helping others in the forums could be rewarded with some type of badges, promotional items, or discounts on kits.

3. Buy some expertise. Buy out or recruit some successful small kit companies, like Briel Computers, for example, or license their designs. Expand them in size to offer better ordering, distribution, manuals, and packaging than a one person outfit can handle.

4. Fill a size niche. I think there is a gap between the small one-person companies and the large electronics firms that Heathkit could fill and be successful while still remaining small and lean.

5. Crowdfund startup costs. Get initial funding using sites like Kickstarter and Indiegogo. Take one good idea, maybe a new solid-state ham radio transceiver like a redesigned HW-8, that is internally a new design but has the original retro look. Fund the cost of getting it to market and get initial orders using crowdfunding. That revenue could then fund R&D for future products.

6. Steal ideas from successful competitors. The experts said you couldn't offer a kit that competed with commercial amateur radio equipment for price and features. Elecraft did it. They said the market for hobbyists is too small? AdaFruit is doing okay. Learn from the successes of competitors and adopt ideas that worked for them.

7. Partner and contract out. Sell through Amazon. Have someone else do kitting. Avoid the need for a big factory and inventory. Run the company as a virtual distributed organization with staff located world-wide.

8. Link it to education. There is a huge demand for learning materials for electronics hardware and software, as evidenced by products like the Arduino and Raspberry Pi. Leverage Heathkit's expertise in developing training materials and courses (one of the last areas where they were successful).

9. Capitalize on nostalgia. Offer some of the original kits again, even if only on the outside. Consider offering some vacuum tube designs. Make the assembly manuals look like the old ones, possibly offering a printed manual (rather than download) as an extra option when ordering a kit.

10. Build credibility and reward early adopters. Lots of people would like to see Heathkit succeed. Offer incentives to people who pre-order. Reward early purchasers and they will give you free marketing. Be open about plans for the future, and the keep promises you make. As just one example, why not make the legacy Heathkit manuals available as free downloads as a goodwill gesture and a sign that Heathkit is serious about coming back?

In summary, I believe Heathkit could re-enter the kit business if they adopt some of the ideas I've outlined here. It won't be easy, and the clock is ticking as the old Heathkit becomes a faded memory, but it can be done.

Wednesday, July 23, 2014

Can Heathkit Make a Comeback? No, and Here's 10 Reasons Why.

Last year Heathkit announced on their website  that they would be making a return to offering kits, placed an extensive survey on their web site, and held a Q&A session where they presented many ideas for kits that they hoped to offer in the near future. Little or nothing has been heard from them in the last few months. Here are ten reasons why I don't think Heathkit can successfully make a comeback to the electronic kit business.

1. Economics. There is a huge one time cost (often called NRE or Ron-Recurring Engineering cost) to bring a new product like a kit to market. You not only have to design a product that works, but it needs to consistently work when built by customers without sophisticated test equipment, you need to develop the assembly manuals, obtain sources for components, stock the parts, have expensive custom plastics and cabinets manufactured, and put all the right pieces in the kits without making errors. If Heathkit is going to sell a kit for, say, a digital multimeter, it will likely cost a couple of hundred dollars. Meanwhile, I can get an assembled, calibrated, and working meter at Harbor Freight for $5 or free with a coupon. In addition, unlike in the past, almost every product today relies on a software component, something that is very expensive to initially develop and needs to continue to be maintained.

2. Startup costs. Similarly, to get economics of scale to be profitable, you need to set up manufacturing, distribution, and agreements with component suppliers. I don't believe that the new owners of Heathkit have deep enough pockets. Are they going to open dozens of retail stores as in the past? When companies like Radio Shack are going bankrupt?

3. The market has changed. While there has been some resurgence, the hobbyist market (sorry, now it's called the "maker movement") is small. Ham radio users are ageing. Probably Heathkit's most popular kit of all time, the HW-101 transceiver, would not have specs that would interest modern hams other than some nostalgia buffs. No one today wants to build a stereo or TV set from a kit.

4. Changing technology. Most new electronic components are only available as surface mount technology (SMT) devices that the average user cannot solder. And forget about getting vacuum tubes in any quantity. Even if they could assemble it (or it came with SMT parts pre-assembled), the average user doesn't have the test equipment needed to test, calibrate or debug modern equipment.

5. Safety. Most kit companies shy away from anything powered by line voltage. It is too easy for the user to electrocute themselves. In the litigious North American market you can be sued if a customer hurts themselves trying to do something they were not explicitly warned not to do in the instructions, no matter how ridiculous. Many of the original Heathkits required aligning or adjusting the equipment under power. But limiting the products to battery operated or external power supplies will make it impossible to offer some of the most interesting kits. This alone could be a showstopper.

6. Too much competition. The market already saturated with established players like AdaFruit, Elecraft, qrpme.com, etc. Many of these are small, Internet-savvy operations with low overhead. Some are run by a single employee on a part-time, break-even basis.

7. The need to go global. In order to get a decent sized market today you have to expand beyond just North America. But this will introduce even more challenges in distribution. How about the famous Heathkit manuals - can they be economically translated into 30 languages?

9. Lack of goodwill. A number of years ago the Heathkit name carried some cachet, but it is now long past it's expiry date. Heathkit has been out of the kit business since the early 1990s, almost 25 years now. The in-house staff and expertise that Heathkit once had is now long gone (most are retired if they are even still alive). They can no longer rely on the Heathkit name to carry any weight with customers

9. Staffing. It is very difficult and expensive to find good engineering staff, especially those with the specialized knowledge to build kits. Technical writing is also expensive and a specialized task that can't be done by the engineers. It takes a long time to build up an engineering team. And will the best people want to relocate to Benton Harbor, Michigan?

10. Differing expectations. If you poll people it seems like everyone would like to see Heathkit come back, but all for different reasons. Some hams want to see the old kits come back, others want new state of the art kits. Some users want computers, robots, radio controlled equipment, and 3D printers. They all have different expectations, but any one of these markets is too small a niche for a viable business.

Given all that, in my next blog post, I will present ten reasons why Heathkit could re-enter the kit business and be successful.

Wednesday, July 16, 2014

Lil Squall ][ Transceiver kit

My latest kit building project is a Lil Squall ][ from qrpme.com. This is a QRP (low power) ham radio transceiver kit that, like most of their kits, is mounted on a tuna tin.

It is based on the Pixie II transceiver design which has been around for a number of years. It is a very minimalist CW (Morse code) transceiver that uses only three transistors and one IC.

I will be making a youtube video about the kit shortly.

Some pictures are shown below.









Wednesday, June 18, 2014

Lego Curiosity Rover Kit

Lego was my favourite toy as a kid (and my 5-year-old grandson says the same thing). I recently saw that Lego had worked with NASA to develop a model of the Mars Science Laboratory Curiosity Rover. The kits were initially hard to find, but a local toy store got a limited number in stock and my wife bought me one for Father's Day.

It's quite a nice kit, made up of 295 pieces and is recommended for ages 10 and up. I put mine together in less than an hour following the instructions. The manual looks quite thick, but some of the
information is duplicated in seven languages. As well as assembly instructions, it gives a nice overview of the Curiosity Rover and it's mission and capabilities.
Montage of Images During Assembly
The kit seems to use mostly standard Lego parts with a few customer pieces. It even comes with a stand/platform to sit on.

I have followed the missions to Mars including the Curiosity Rover, and was familiar with it, but putting the kit together really helped me visualize what the real rover is like.

Curiosity Rover on Mars (or maybe the backyard)
If you can get your hands on one, I recommend the kit for yourself and/or any Lego or space enthusiast.

Wednesday, June 11, 2014

Abandoned Farmhouse Adventure now in Google Play Store

Back in April 2012, I wrote a text adventure game  as an experiment to try out the CC65 C compiler on the Briel Replica 1 computer  (an Apple 1 replica). Because it was written in C, it also ran under Linux, and any platform that supported a reasonable C compiler. I also ported it  to the Briel Altair 8800 computer running CP/M using the BDS C compiler.

When the Raspberry Pi store opened, I packaged it and submitted it as one of the first applications in the Raspberry Pi store.

Later, I made a GUI version using the Qt Toolkit , which is portable to a number of platforms. I intend to release the Qt version into the Raspberry Pi store, but have not gotten around to doing that yet.

With Qt now supporting Android, I tried building it for Android to run on a tablet, and it worked almost flawlessly without any changes. I made a few small tweaks for Android, and packaged it for the Google Play store. It is now available as a free Android application.

Android Version of The Abandoned Farmhouse Adventure
I doubt that any application before has run on an Apple 1, CP/M, Linux desktop, Raspberry Pi, and Android tablet - devices that span almost 40 years of computing and differences in computing power of several thousand times.

Tuesday, June 10, 2014

Freq-Mite Kit Assembled

Today I received and assembled a Freq-Mite kit. It is a tiny 1.75 inch by 1.25 inch circuit board with a PIC that measures frequency and reports it in Morse code. You typically install it in a radio receiver or transceiver that lacks a digital display and use it to accurately report your frequency. You can program the IF frequency of your radio using jumpers so that it correctly adjusts for the IF offset. It also works with direct conversion receivers.

I ordered a kit, which sells for US$22 in USA and US$30 elsewhere, including shipping, and it soon arrived in my mail box. It has only about 20 components, all through hole, and I was able to assemble it in less than an hour.

The kit comes with all parts.
The assembled board, before inserting the PIC chip and wires.
Powering it up on the bench with a small speaker and RF signal generator, it accurately reported the frequency that was input to it.

Testing it on the bench.
I plan to install it inside one of my QRP rigs, probably the Heathkit HW-8 . I suspect I may have to order another one or two of these for other rigs that I own.

Monday, June 2, 2014

New Retro Computer Kit

Dubbed a Software Defined Computer, the Propeddle  is a new forthcoming computer kit that has a 65C02 processor as well as a Propeller CPU, and is planned to be able to emulate various 6502-based computers by changing the software. The prototype is already able to emulate an Apple 1.

The name Propeddle comes from the Propeller CPU used on the board, and Chuck Peddle, one of the designers of the 6502 microprocessor.

It has similarities to the Briel Replica 1, but aims to be able to be able to emulate different computers.

It looks like a interesting project, and one that I will keep my eye on. Being able to emulate a number of different old computers would be cool. It should be able to emulate, say, a KIM-1, Commodore PET, or Ohio Scientific Challenger by changing the firware. I wonder if it will have the processing power to emulate a more complex machine like the Apple II?

Wednesday, May 21, 2014

Updates: Apple II Monitor Port and GR-64 Video

A couple of updates to recent blog posts: I did a little more work on the Apple II Monitor port to the Apple 1, getting the source code to assemble the version that includes the Woz Monitor at the end. This version can be burned to a ROM (or EPROM or EEPROM) in the Replica 1, so you can have both the original Woz Monitor and Apple II Monitor in ROM from powerup. I confirmed that it does work when programmed into a ROM. It also works in the POM1 Apple 1 Emulator. As before, the Apple II Monitor port can be found here.

Tuesday, May 13, 2014

Apple II Monitor Running on Briel Replica 1

As a followup to my previous blog post, here is a transcript of running some Apple II Monitor commands on the Briel Replica 1. You can find documentation on the Monitor commands in a number of places, including here. The commands typed by the user are in bold.


Monitor prompt:

*

Dump memory:

*1000.100F
1000- A2 10 EA CA D0 FA 60 BE
1008- 00 00 4A 83 00 00 75 D7

Change memory:

*1000:01 02 03

*1000.100F
1000- 01 02 03 CA D0 FA 60 BE
1008- 00 00 4A 83 00 00 75 D7

Move Memory:

*1000<2000 .2fffm="" b="">

Verify Memory:

*1000<2000 .3000v="" b="">
3000-FF (00)

Disassemble:

*FF00L
FF00-   D8          CLD   
FF01-   58          CLI   
FF02-   A0 7F       LDY   #$7F
FF04-   8C 12 D0    STY   $D012
FF07-   A9 A7       LDA   #$A7
FF09-   8D 11 D0    STA   $D011
FF0C-   8D 13 D0    STA   $D013
FF0F-   C9 DF       CMP   #$DF
FF11-   F0 13       BEQ   $FF26
FF13-   C9 9B       CMP   #$9B
FF15-   F0 03       BEQ   $FF1A
FF17-   C8          INY   
FF18-   10 0F       BPL   $FF29
FF1A-   A9 DC       LDA   #$DC
FF1C-   20 EF FF    JSR   $FFEF
FF1F-   A9 8D       LDA   #$8D
FF21-   20 EF FF    JSR   $FFEF
FF24-   A0 01       LDY   #$01
FF26-   88          DEY   
FF27-   30 F6       BMI   $FF1F

Mini-Assembler:

*7666G

!1000:LDX #$10
1000-   A2 10       LDX   #$10
! NOP
1002-   EA          NOP   
! DEX
1003-   CA          DEX   
! BNE 1000
1004-   D0 FA       BNE   $1000
! RTS
1006-   60          RTS   

Call Monitor to Disassemble:

!$1000L
1000-   A2 10       LDX   #$10
1002-   EA          NOP   
1003-   CA          DEX   
1004-   D0 FA       BNE   $1000
1006-   60          RTS   
1007-   BE 00 00    LDX   $0000,Y
100A-   4A          LSR   
100B-   83          ???   
100C-   00          BRK   
100D-   00          BRK   
100E-   75 D7       ADC   $D7,X
1010-   00          BRK   
1011-   00          BRK   
1012-   F8          SED   
1013-   87          ???   
1014-   00          BRK   
1015-   00          BRK   
1016-   B5 F6       LDA   $F6,X
1018-   42          ???   
1019-   00          BRK   

Go back to Monitor:

!$7F65G

Single step:

*1000S
1000-   A2 10       LDX   #$10
 A=10 X=10 Y=7D P=70 S=CA
*S
1002-   EA          NOP   
 A=10 X=10 Y=7D P=70 S=CA
*S
1003-   CA          DEX   
 A=10 X=0F Y=7D P=70 S=CA
*S
1004-   D0 FA       BNE   $1000
 A=10 X=0F Y=7D P=70 S=CA
*S
1000-   A2 10       LDX   #$10
 A=10 X=10 Y=7D P=70 S=CA
*

Display 6502 Registers:

*^E
 A=10 X=10 Y=7D P=70 S=CA

Hex arithmetic:

*12+34
=46
*FE-12
=EC

Go to BASIC:

*^B
>LIST

Sunday, May 11, 2014

Apple II Monitor Ported to Apple 1

As announced here,  a cassette tape was found that contains a port of the Apple II Monitor to the Apple 1. It was done by Winston Gayler. Additional work was done by Wendell Sander, who posted documentation, cassette tape sound files and Woz Mon binaries here .

I've tested the code on a Briel Replica 1 and it works quite well. The only issue I found on the Replica 1 is that the commands that require Control keys do not work as the Replica 1 does not emulate Control keys when using a PS/2 keyboard. They will work if entered from the serial port.

This weekend I went a little further adapted the original monitor source from the "Red Book" to build under the CA65 assembler, then applied the changes for the Apple 1. The result is code that can be assembled from source and easily relocated.

References:

  1. www.apple1notes.com/old_apple/Monitor_II_on_1.html
  2. www.applefritter.com/content/apple-ii-monitor-ported-apple-1
  3. github.com/jefftranter/6502/tree/master/asm/Apple%5D%5BMonitor


Thursday, May 8, 2014

Heathkit GR-64 Restoration

My latest radio restoration project is a Heathkit GR-64 Shortwave Receiver. This was a low-end receiver made from 1964 to 1971 and originally selling for $39.95. It covers AM and shortwave in four bands and utilizes four tubes.


This one was acquired on eBay. Other than the usual scratches and small cracks around the plastic front panel, it looked to be in pretty good shape. It had suffered a bit in shipping with some tubes and the power transformer coming loose, but there did not seem to be any damage. It appeared to be complete, and when powered up it picked up several AM stations.

The shortwave bands didn't seem to be working well, if at all, and the S-meter was always off scale.

A check of the components showed that most resistors had drifted up in value, as is normal for the old carbon composition type. I replaced a few were 20% off or more. I figured that was the likely case of the S-meter problems, as it uses some resistors as a voltage divider to compare the AVC voltage to a reference value.


However, that did not fix the problem. I spent considerable time poking around, checking components and wiring. I tried swapping some of the tubes with known good ones from a Heathkit AR-3.

After lifting several resistors in the AVC circuit, there was still a resistance of about 60K to ground that should not be there and I could not account for.


The printed circuit board really had a lot of rosin flux residue on it. On a hunch, I scraped some of it off, and the mysterious resistance to ground went way up. After cleaning the board with alcohol to remove the flux, the resistance became too high to measure. The S-meter also started reading on scale. Lesson learned - flux residue can cause problems in high impedance circuits. Obviously this flux was there since the kit was built but whether it caused a problem from day one or only later, who knows.

The next problem was that it was dead on bands other than AM. Actually band D was working (poorly). There was no local oscillator activity at all on bands B and C. All the coils looked good. But I was seeing a low resistance between the local oscillator tuning capacitor and ground on bands B through D that should not be there, according to the schematic. The local oscillator frequency on band D was also way off.

After a bit of tracing of the circuit I found the cause: two wires that crossed were touching where there was insulation missing and were shorted. One was the antenna lead and the other was from the local oscillator. After pulling them apart, the local oscillator started running on all bands.

I did a full alignment and it all went well -- I could align each band on each end of the dial. Because of the low 455 KHz IF frequency you have to watch out that you don't align to the image frequency that is only 910 KHz away from the correct one. The manual mentions this in the procedure, but I almost did this on one band and thought at first that I could not get it to align correctly.


Restoration is now almost complete. The S-meter is still off scale for no signal, so I expect to have to tweak some of the resistors in the circuit.

The limited testing I have done indicate that the radio is reasonably sensitive and can pick up lots of shortwave broadcast signals with a decent antenna. It would not be very suitable for amateur radio, as bands like the 40 meter ham band only take up a small portion of the dial. The BFO is also hard to use as it is not very stable and interacts with other controls, so it could be used for strong CW signals but would be frustrating for SSB.

I plan to make a YouTube video on this radio as I have done for the other models I own, so watch for that in the coming weeks.

Wednesday, May 7, 2014

Toroidal Inductors

I was reading through my 80th anniversary reproduction of the first  Radio Amateur's Handbook, published in 1926. At the back are advertisements from electronics companies.


An ad from Cardwell Condensors lists some of the contributions the company made to radio and electronics, such as "the first commercial Neutrodyne". One of them caught my eye:

"The first Toroid (abandoned due to inherent electrical defects in this type of coil, impossible to overcome!)"


Those of us who have been around electronics probably think of toroidal inductors as a relatively new phenomenon. When I started in the 1970s and 80s most inductors were wound on cylindrical cores, and back in the 1920s and 30s the most common was air wound inductors, often featuring exotic methods of winding and ways to shield or arrange coils to minimize interference with each other. But for the last couple of decades, the doughnut-shaped toroidal inductors have been the most popular type for RF use. It is interesting that someone explored toroidal inductors back in the 1920s, and a mystery why they concluded that it was not a feasible design. Perhaps the core materials available to them at the time were a factor (modern toroids use ferrites and powdered iron cores). I'd be interested in hearing anyone's ideas or theories.

The company is still in business, so maybe I will ask them about it.

More information on toroidal inductors can be found in this Wikipedia article.

Monday, April 21, 2014

Building the Softrock Ensemble II Software Defined Receiver

A recent hardware project of mine was to build a Softrock Ensemble II kit. This is a Software Defined Radio amateur/shortwave radio receiver. Software Defined Radio, or SDR, is a relatively new trend in radio technology that utilizes software running on a computer to perform much of the processing of the radio signals. In the case of the Softrock, it uses a PC and sound card for signal decoding and playback.


Details of the Softrock series of radios are well covered in many articles. I'll just mention some of my experiences constructing the kit.

Overview

The kit comes with all parts other than cables and power supply. There is a very nice optional case available which I opted for.

While it is a small board, there are many components to install, both through-hole and surface mount, on both sides of the PCB.

I assembled my unit over a period of about ten days, working an hour or two most evenings. I encountered no major problems. A few assembly details I had to confirm on Internet postings. I have only briefly tested it with a PC so far, but was able to pick up quite a few amateur radio signals just using a short piece of wire for an antenna (while I was building it my amateur radio antenna was down to do roofing work).

Having built the kit, I can offer a number of suggestions and advice to other kit builders.

Suggestions

There are a significant number of parts on the kit. Take an inventory of them all and check them off against the parts list. The board is built in functional blocks. Either separate all the parts for each functional block, or do so when you start working on a block.


Take your time with assembly. I like to make a hardcopy of assembly instructions rather than reading them off of a computer screen. This allows me to check off the steps and make notes.

Check the parts carefully. I generally built no more than one functional block in a session, as per the assembly instructions. Because there are HF and LF versions, there are differences in construction and you will have some extra parts left over. Make sure you use the correct set of instructions for the model you are building. The on-line instructions are good but there are some minor typos. Some potentially confusing instructions are related to PCB changes and coil winding. Some modifications described are no longer applicable to the latest revision of PCBs, so watch out for this.


The SMD soldering may look daunting, but it can be done with a steady hand. Use a small tip and small diameter solder. Use a magnifier and inspect you work carefully for good joints and no solder bridges. Watch some of the SMD soldering videos on the Internet. The only trouble I had was with some solder bridges around the oscillator module. It has extra pins that should not be connected and they got bridged. Liquid solder paste may be helpful when soldering, but I did not have any when I built mine. I did clean the tracks first with a soft eraser. If the assembly is beyond your comfort level you can buy the radio assembled. Or you may want to build the simpler and lower cost single band Softrock Lite II version.

Measure all parts with an ohmmeter and cap meter if you have one (e.g. in your DMM). While parts are unlikely to be bad, it is easy to misread the colour codes and install the wrong part (particularly for resistors). As I have a digital LC meter, I also measured the inductance of the toroids after winding them just to double check.


Some people don't like winding toroidal inductors. This kit has a lot (12 coils and three transformers), but most of them are straightforward single winding coils. Assembly is not too hard, although some of the cores are quite small. The coils use larger gauge wire than the transformers, which is easier to strip without breaking the wires.

Follow all the tests for each stage. This can be done with a DMM, although an oscilloscope is nice to have. A frequency counter, if you have one, is also helpful.


For power, use a decent regulated power supply, not a "wall wart". I found this low cost supply [picture] on Amazon that is switchable for different voltages and comes with all the common power connectors, and is regulated.



I recommend ordering the optional case. It makes the unit look professional and protects it. Join the Yahoo Softrock discussion group. Expect to spend a lot of time setting up and learning the software side. There are several software packages to choose from.


I have only done some preliminary testing of the unit hooked up to a computer, but it seems to be working fine. I will probably post more updates here after I have played with it some more.

References
  1. Five Dash Inc - source for Softrock Radio Kits
  2. WB5RVZ.ORG - KITS' Documentation Home Page
  3. Softrock-40 Yahoo Interest Group


Saturday, April 19, 2014

Running dBASE II on CP/M

A viewer of my YouTube video on running various CP/M applications on the Briel Altair 8800 kit suggested I look at dBASE II. dBASE II was one of the first database management systems for microcomputers. I'm not particularly interested in databases, but I thought I would give it a try.

I downloaded dBASE 4.1 from www.retroarchive.org. I unzipped it, copied the files to an SD card, booted up CP/M, and copied all files to an empty CP/M B: drive.


While it runs out of the box, running INSTALL will let you configure the terminal type and use it in full screen mode. From the install program, you pick a VT-100 terminal type that should work with the Briel Altair's display. A session is shown below.

B>install

dBASE II INSTALLATION PROGRAM  VER 3.0

ARE FULL SCREEN OPERATIONS WANTED (Y/N)? y

  dBASE II INSTALLATION PROGRAM  VER 3.0
                 MENU #1

A -ADDS VIEWPOINT   M -HP 2621
B -ADM-31           N -INTERCOLOR
C -ADM-3A           O -KAYPRO II
D -APPLE ///        P -NEC PC-8000/1
E -APPLE II 40 COL  Q -NS ADVANTAGE
F -CROMEMCO 3102    R -OSBORNE I
G -DIALOG 81        S -PERKIN ELMER 11
H -EAGLE AVL        T -SANYO MBC 3000
I -GNAT-SYSTEM 10   U -SOROC
J -HAZELTINE 1500   V -SPERRY UTS 40
K -HEATH 89         W -SUPERBRAIN
L -HP 125                          

     X - MENU #2
     Y - MODIFY PREVIOUS INSTALLATION
     Z - USER SUPPLIED TERMINAL COMMANDS

SELECT TERMINAL TYPE: X

   dBASE II INSTALLATION PROGRAM  VER 3.0
               MENU #2

A -TELEVIDEO                   
B -TOSHIBA T100                
C -TOSHIBA T250                 
D -TRS-80 (FMG)                 
E -TRS-80 II (P&T)              
F -TRS-80 III                   
G -VECTOR GRAPHICS              
H -VISUAL-100                   
I -VPD-80                       
J -VT-100                       
K -XEROX 820                   

     X - MENU #1
     Y - MODIFY PREVIOUS INSTALLATION
     Z - USER SUPPLIED TERMINAL COMMANDS

SELECT TERMINAL TYPE: J

CHANGE MACRO, DATE, ETC. (Y/N)? N

TYPE "Y" TO SAVE, ANY OTHER KEY TO ABORT INSTALL
Y
SAVING INSTALLATION PARAMETERS

B>

Running DBASE will start the application. The HELP command will display general information on the application and more details on each command. Below is a short session.

B>dbase

ENTER TODAYS DATE  OR RETURN FOR NONE 
 (MM/DD/YY) :04/19/14

Copyright (C) 1982 RSP Inc.

***  dBASE II     Ver 2.4  1 April, 1983

 Type 'HELP', 'HELP dBASE', or a command  

. help dbase

       HELP TEXT FILE DBASEMSG.TXT VERSION 1.12 FOR dBASE II v2.4
                Copyright 1983 Ashton-Tate and RSP, Inc.

        written by Wayne Ratliff, Jim Taylor, and Howard Dickler

                         INTRODUCTION
     
     This entry is intended to give you on-line information about your dBASE 
II  Database  Management  System.   It  explains the  disk  files  you  have 
received,  and  gives suggestions on tapping the power now available to  you 
for  data  management.   Using  the on-line HELP in  conjunction  with  your 
Manual,   you will soon be creating databases and writing command procedures 
to do your work. 

                    >>>>> type any key to continue <<<<<
WAITING 

                       HOW TO USE THE 'HELP' FACILITY

     Information about your dBASE  II  system can be obtained by typing 
HELP and any of the following key words: (e.g. HELP NEW )

          UTILITIES      FULL-SCREEN    LIMITS    BACKUP  
          INSTALL        NEW            ERRORS    CP/M
          EXAMPLES       FUNCTIONS      DBASE     HELP       RUNTIME
               (or any dBASE II command)

     dBASE will then look up the entry for the key word and display it.   If 
there is no information on the subject then dBASE will say "NO HELP MESSAGES 
FOUND".   When there is more text to display beyond what's shown,  then  you 
will see the word 

WAITING  (like this)

                   >>>>>  type any key to continue. <<<<<

WAITING 

. list
NO DATABASE FILE IN USE, ENTER FILENAME: invent.dbf

00001  123456 QUIRKY LITTLE QWARK     99.00   230.00   23  100 
00002  258741 PORTABLE POOL          450.00   999.99   20   40 
00003  258963 ELEPHANT COLLAR          3.00    15.00    3   10 
00004  123345 HOUSE WRAPPER           45.00   100.00  200  100 

. display structure

STRUCTURE FOR FILE:  B:INVENT  .DBF
NUMBER OF RECORDS:   00004
DATE OF LAST UPDATE: 03/09/83
PRIMARY USE DATABASE
FLD       NAME      TYPE WIDTH   DEC
001     PRD:NMBR     C    006          
002     PRD:DESC     C    020          
003     PRD:COST     N    007    002   
004     PRD:PRIC     N    007    002   
005     ONHAND       N    003          
006     ONORDR       N    003          
** TOTAL **             00047

. list

00001  123456 QUIRKY LITTLE QWARK     99.00   230.00   23  100 
00002  258741 PORTABLE POOL          450.00   999.99   20   40 
00003  258963 ELEPHANT COLLAR          3.00    15.00    3   10 
00004  123345 HOUSE WRAPPER           45.00   100.00  200  100 
00005  998783 My widget               13.99    24.50   10   99 
00006  988765 Brand new car            0.00     0.00    1  999 

. quit
*** END RUN     dBASE II     ***

Thw screen shot below shows adding new a database record in full screen mode with the APPEND command.



dBASE was quite innovative for its time and was one of the "killer applications" that drove the adoption of early microcomputers for business use. You can learn more from this Wikipedia article. The company behind dBASE is still in business and can be found at dbase.com.

Friday, April 18, 2014

Book Review - The WOZPAK Special Edition

A great book for fans of the early Apples. A bit of everything - some history, software listings, and hardware mods and information. Some material is available elsewhere but there is nothing like having it all in hardcopy in a single volume. The original Apple monitor listing handwritten by Woz - it doesn't get better than this!

It's quite a big book at 8.5" x 11" and over 350 pages, and the binding and print quality is good. Highly recommended for anyone who is interested in the Apple 1 and 2 series or early microcomputers and the 6502 microprocessor.

More information can be found here:

  1. http://wozpak.callapple.org/
  2. http://www.lulu.com/shop/bill-martens-and-brian-wiser/the-wozpak-special-edition-steve-wozniaks-apple-1-apple-computers/paperback/product-21145348.html

Thursday, April 17, 2014

Book Review - Collectible Microcomputers

Collectible Microcomputers by Michael Nadeau
160 pages, published by Schiffer Publishing Ltd, 2002.

I recently bought a new copy of this book. It has been out for some time, but is still relevant if you are interested in old computers.

The book has information and hundreds of pictures of old microcomputers, ranging from the early days of the Apple 1, Altair, and CP/M machines, through to the 8-bit era of Commodores and Apple ][ series, up to the early IBM PC and compatibles. It even covers some rarities like the Hyperion portable which was developed here in Ottawa, Canada.

Reading the book was a trip through memory lane for me, seeing computers that I had used in the past as well as many that I had only heard of.

I was struck by a few things as I looked over the book. First, I don't think many people realize how expensive some of these early computers were when new. For example, the NeXtcube sold for $11,495 in 1990; that's over $20,000 today. In many cases there was little or no commercial software available - you had to write it yourself. You had to be very forward thinking and perhaps a little crazy to invest in something that expensive. No wonder that so many of the early users seemed to be medical doctors.

Second, there used to be a huge variety in computers as far as appearance and operating systems offered. Something was definitely lost when the world moved to the majority of desktops being boring IBM PC compatibles.

Finally, if the price guide is accurate, the value of old collectible computers has soared since this book was published in 2002. The Apple //e, for example, is valued at $2 to $45. With the advent of eBay they now routinely go for hundreds of dollars. The Apple 1 is valued at $12K to $25K, but units have now sold at auction for over $200K.

The book does not have room for detailed specs on each computer, but covers a lot of machines and has some historical material on most of the manufacturers.

It is available, new or used, on amazon.com.

Wednesday, April 16, 2014

My Text Adventure Game Running on CP/M

After a couple more hours of work and I have my Abandoned Farmhouse text adventure game ported to CP/M using the BDS C compiler. The changes were similar to those needed for the Yum game, and included some changes for the available string functions and initialization of some large arrays.

I haven't played the game to completion but it seems to be working well. You can find source code and a CP/M binary here.

Below is a transcript of playing a short game.


B>advent
                      Abandoned Farmhouse Adventure
                            By Jeff Tranter

Your four-year-old grandson has gone missing and was last seen headed in the
direction of the abandoned family farm. It's a dangerous place to play. You
have to find him before he gets hurt, and it will be getting dark soon...

? help
Valid Commands:
Go east/west/north/south/up/down
Look
Use object
Examine object
Take object
Drop object
Inventory
Help
Quit
You can abbreviate commands and directions to the first letter.
Type just the first letter of a direction to move.
? i
You are carrying:
  flashlight
? l
You are at the door to the house.
You see:
  key
  bottle
You can go: east west
? drop flashlight
Dropped flashlight.
? t key
Took key.
? t bottle
Took bottle.
? n
You can't go north from here.
? l
You are at the door to the house.
You see:
  flashlight
You can go: east west
? w
You are in the kitchen.
? l
You are in the kitchen.
You see:
  candybar
You can go: south east down
? t candybar
Took candybar.
? w
You can't go west from here.
? l
You are in the kitchen.
You see:
  nothing special
You can go: south east down
? s
You are in the dining room.
? l
You are in the dining room.
You see:
  stale meat
You can go: north west
? u stale meat
The meat looked and tasted bad. You feel very sick and pass out.
Game over after 7 turns.
Do you want to play again (y/n)? n

B>

Tuesday, April 15, 2014

Yum Game ported to BDS C

I've been playing some more with the Briel Altair 8800 running CP/M.

As a larger test of the BDS C compiler I was able to port the "Yum" game that I originally wrote to run on the Briel Apple Replica 1.

Porting it to BDS C was a few hours of work (mostly spent transferring new versions of the code between my Linux desktop and SD card and compiling on the Altair 8800.

The changes required were not too major. I was impressed by the reasonably complete run-time library included with BDS C. In all, the changes I had to make were the following:

  • Includes changed (BDSC C has everything in stdio.h).
  • sizeof does not work for arrays, so used a constant.
  • Arrays cannot be initialized, but can use initptr() function instead.
  • No bool type, so use int.
  • Function declarations have to use old K&R format.
  • Text supports lower case (original Apple 1 version had to be upper case only).
  • Some text lines (like help) made wider due to 80 column screen.
  • Variables cannot be initialized when declared.
  • No strtol() so use atoi().
  • Remove const qualifiers.
  • Clear screen using ANSI escape sequence.

Below is a partial log of a session playing the game against the computer.



#     # #     # #     #
 #   #  #     # ##   ##
  # #   #     # # # # #
   #    #     # #  #  #
   #    #     # #     #
   #    #     # #     #
   #     #####  #     #


Welcome to Yum!
Do you want instructions (y/n) ? y

This is a computer version of the game Yum, similar to games known as Yahtzee,
Yacht and Generala. Each player rolls five dice up to three times and then
applies the dice toward a category to claim points. The game has 12 rounds
during which each player attempts to claim the most points in each category.

The winner is the person scoring the most points at the end of the game.
This version supports up to three players of which any can be human or
computer players.

Categories are as follows:
1'S through 6'S - dice of same type
Low Straight (15) - 1 2 3 4 5
High Straight (20) - 2 3 4 5 6
Low Score - total 21 or more
High Score - total 22 or more
Full House (25) - 3 of a kind and pair
Yum (30) - 5 dice the same
Bonus of 25 points if upper section is 63 or more.

How many human players (0-3)? 1
How many computer players (0-2)? 1
Name of player 1? Jeff
Press to start the game
Wait a few seconds, and type a CR: 

Jeff's turn. Press to roll 
First roll is: 2 2 2 4 5
Enter dice to roll again or D for dice or S for score: 4 5
Second roll is: 2 2 2 2 2
Enter dice to roll again or D for dice or S for score: 

 1  - 1'S
 2  - 2'S
 3  - 3'S
 4  - 4'S
 5  - 5'S
 6  - 6'S
 9  - Low Straight
10  - High Straight
11  - Low Score
12  - High Score
13  - Full House
14  - Yum

Jeff, What category do you want to claim? (1-14)? 14

Altair's turn. Press to roll 
First roll is: 1 1 4 4 5
Altair keeps: 1 1 4 4
Second roll is: 1 1 4 4 5
Altair keeps: 1 1 4 4
Last roll is: 1 1 2 4 4
Altair plays 1'S

Press to continue 

Score after 1 of 12 rounds:

Roll           Jeff    Altair  
1'S                    2       
2'S                            
3'S                            
4'S                            
5'S                            
6'S                            
Sub-total      0       2       
Bonus          0       0       
Low Straight                   
High Straight                  
Low Score                      
High Score                     
Full House                     
Yum            30              
Total          30      2       

Press to continue 

Jeff's turn. Press to roll 
First roll is: 1 2 2 6 6
Enter dice to roll again or D for dice or S for score: 1
Second roll is: 2 2 4 6 6
Enter dice to roll again or D for dice or S for score: 4
Last roll is: 2 2 6 6 6

 1  - 1'S
 2  - 2'S
 3  - 3'S
 4  - 4'S
 5  - 5'S
 6  - 6'S
 9  - Low Straight
10  - High Straight
11  - Low Score
12  - High Score
13  - Full House

Jeff, What category do you want to claim? (1-14)? 13

Altair's turn. Press to roll 
First roll is: 2 4 4 6 6
Altair keeps: 4 4 6 6
Second roll is: 4 4 4 6 6
Altair keeps: 4 4 4 6 6
Altair plays Full House

Press to continue 

Score after 2 of 12 rounds:

Roll           Jeff    Altair  
1'S                    2       
2'S                            
3'S                            
4'S                            
5'S                            
6'S                            
Sub-total      0       2       
Bonus          0       0       
Low Straight                   
High Straight                  
Low Score                      
High Score                     
Full House     25      25      
Yum            30              
Total          55      27      

Press to continue


I put the source code as well as a CP/M binary here on github.  Next, I plan to try porting my text adventure game.