Bob Bishop’s Apple 1 Trade In Deal – and just when did Apple II’s first ship

November 17th, 2014

Apple 1 and Apple II programmer, Bob Bishop recently passed away. Though I didn’t know Bob Bishop, I did exchange a few emails with him in June of 2013. From the few emails I exchanged with him, I got the impression that Bob was a good guy, and I feel it’s unfortunate that I never got to meet him in person.

Back in June of 2013, while refining the Apple 1 Registry, I noticed that at one time, that Bob had an Apple 1. I sent him an email, asking if he still had his unit. Bob replied, saying that he had traded it in. This was about the time that Fred Hatfield’s Apple 1 was sold at auction. There was much in the press about Fred’s Apple 1, which included a letter from Jobs, offering a trade in deal. This was a deal which Fred had refused. Bob was a little concerned that the trade he made, wasn’t as good as what Fred and others were offered.

Here is the story of that trade in, in Bob’s words. The article he mentions, was a New York Times article that included some mention about how aggressively Apple pursued the Apple 1 trade in program.

When I read that article, I was a little upset (and said so on my weekly radio show) to discover that the company had “an aggressive trade-in program, offering Apple II’s and sometimes cash incentives in exchange for Apple-1’s.” When I wanted to do MY trade-in, I had to go to apple and ask THEM if they would be willing to do it. They said YES… but only if I paid THEM some additional money! But I guess that was before they had fully started their trade-in program. So it may be that I have the dubious distinction of having been the very first person to trade-in my Apple-I for an Apple-II (since the serial no. of the Apple-II that I got was 0013). :)

But now that you’ve showed me the original letter from Fred, It looks like the NY Times article may have gotten their information a little mixed up. According to the letter, it appears that Fred had to pay THEM the $400 — and not the other way around (just as in my case).

I don’t remember exactly how much I had to pay when I made my trade-in, but I think it was about the same amount ($400). And I made the trade-in around late June of 1977, but Apple didn’t ship the computer to me until July. (I remember that they said it would be delivered to my home in the next few days. So on July third, I sat around anxiously waiting for delivey. The next day was going to be the Fourth of July, and if it didn’t come today, I would have to wait two more days to get it! Well, it didn’t come… so I had a very miserable Fourth of July that year. But around 10AM on July fifth, it finally arrived! :)

– Bob -

By the way, surviving evidence indicates that though Apple 1 trade ins occurred, it wasn’t a real great deal. Several surviving Apple 1’s that came through the hands of early Apple employees, were probably trade-in’s, but there aren’t that many of them. The only person that I know of, that actually acknowledged that he traded in an Apple 1, was Bob Bishop.


November 14th, 2014
diode in copper

diode in copper (crop of image by Jack Rubin)

Last Friday, I thought I froze the layout for the final time. I took a few looks at it, checking for correctness over the last week, finding nothing to fix or improve upon. Today, I planned on kicking off the build, after doing a final check. However, during this “last” check, I noticed that the diode symbols were missing on the front copper layer. The are not obvious, as they are obscured by the actual diodes. I’ll have to add them in, recheck the layout, regenerate the Gerbers and do some final checking (yet again). Hopefully the PCB will be ready to order by Monday. After that, it will take about four weeks, plus or minus, to be manufactured, shipped, built and tested.

Amateur Radio General License Exam

November 13th, 2014

In the USA, there are currently three classes of amateur radio licenses, Technician, General and Extra. Each advancement in class gives the license holder additional broadcast privileges.

Yesterday, I passed my Amateur Radio (AKA HAM) General License exam. This gives me permission to broadcast RTTY data on a number of additional frequencies over the Technical License that I already held. Though I’m not entirely set up with the software and the hardware I need for RTTY, getting the General License is another step toward getting “on the air”.

Since passing the General test, allows you free attempt at the Extra test in the same test session, I gave it a try. Out of 50 questions, I had 29 correct, 8 short of what I needed to gain an Extra license. Since I’ve gone this far, and am apparently pretty close to knowing enough to obtain an Extra license, I figure I might as well continue studying for a couple more months and see if I can obtain the Extra license.

Memory Test for the 8008 Posted on my 8008 Software Page

November 2nd, 2014

This was ported to the 8008 from my 6502 memory test program by Mark Arnold. I have made some modifications to his port, so any problems are solely my fault.

It contains a couple of enhancements over the 6502 version.

  • It does not stop on error
  • It keeps a running count of errors that is displayed every pass

    By the way it’s been running for the last hour, checking out the 12K of memory installed on my reproduction 8B, without reporting any errors.

    I suppose someone who needed a good 8080 memory test could port it to the 8008 or Z80 without too much trouble.

    Woz’s take on the Apple 1’s noisy -5 volt supply

    October 30th, 2014

    There was a recent thread about the Apple 1’s noisy -5 volt supply on Applefritter, so I asked Woz the following:

    One thing a number of us have noticed while working with reproductions of the Apple 1, is the amount of noise that exists on the -5 volt supply. The stabiliy of the -5 volt rail appears to be affected by the edges of the -12 volt clock that is used to control the video shift registers. Usually it’s not a problem, but I’ve run across a few cases where it affected DRAM reliability. Adding additional decoupling to -5 near the shift registers and the -5 regulator seems to clean things up considerably.

    I was wondering if any of you remember noticing that noise on the -5 volt supply and if that ever was an issue back “in the day”.

    I recieved the following reply from Woz:

    I am sure that what you describe is valid, although I personally wasn’t aware of it.

    I did the prototype of the Apple I and debugged the PC board version but didn’t look into such aspects. I’m sure you are quite correct. We knew that this was a low volume product since we were demonstrating the Apple II before shipping the first Apple I. Hence, we did not have many to become aware of issues like this. Part of the problem was that my time was being spent on the Apple II completion.

    The ‘productizing’ of the Apple I came under Steve Jobs. I always optimized my prototypes for short distance wiring, but the PC board introduced longer power traces. Please forgive me. I never looked closely at this aspect. I certainly over-minimized in bypassing decoupling capacitors throughout the chips and RAM. I did worse too that was probably copied over to the PC board, like not having pullup resistors on unused TTL inputs. Still, had we at Apple been aware of such an issue while selling maybe 150 Apple I’s, we could and would easily and quickly have rectified it. But we didn’t test fully a product that was a temporary place-holder before the big product. We did try to buy back every Apple I in exchange for Apple II’s.

    We had more luck than anyone deserves with things working out just enough to suffice and do what we did.

    I will tell you that I and others did observe the power lines and did not notice noise or spiking. And, as I said, it was never a problem that was called to our attention, or at least to my attention. We could have put out an errata sheet for owners to fix the problem themselves, since this was very much a maker product (local stores could modify things to use 16K RAM’s, for example, and they did.

    I am totally interested in hearing such things even after all these decades. I awoke one night in Quito, Ecuador, this year and came up with a way to save a chip or two from the Apple II, and a trivial way to have the 2 grays of the Apple II be different (light gray and dark gray) but it’s 38 years too late. It did give me a good smile, since I know how hard it is to improve on that design.


    Marconi 2018A Signal Generator

    October 27th, 2014
    Marconi 2018A

    Marconi 2018A

    I recently picked this up off of eBay for less than $200, including the cost of shipping. Though ebay is a crap shoot, this time, I think I scored. It seems to work perfectly with the frequency and power output exactly matching my Kenwood TS-530S. The seller listed it as having an intermittent keyboard problem. I haven’t see any sign of that, but did notice in the manual that if reverse power exceeds a certain level that it will lock up the keyboard until power cycled. I’m guessing that this is what happened to the previous owner. There is a calibration sticker on the front that says “CALIBRATION LMITED to Residual FM <10Hz 01-16-2013 TECH 057", so it seems that it had some sort of calibration, just last year. This unit has seem a lot of use, as the lettering on some of the keys has worn off, but I can live with that.

    The manual for this device lists a copyright date of 1984, so the design has been around a while. The METRICTEST.COM website says that the manufacturer list price in the US was $5,995 for the 2018. Here is a little more about the specifications of this device.

    Performance Characteristics:
    Minimum Frequency: 80 kHz
    Maximum Frequency: 520 MHz
    Frequency Resolution: 10 Hz
    Time base stability: 0.1 /mo
    Minimum Output Power: -127 dBm
    Maximum Output Power: 13 dBm
    Power Resolution: 0.1 dB
    Output Accuracy: 1 dB
    Output Impedance: 50
    Ohm Maximum Single-Side-Band Noise: -130 dBc/Hz
    Harmonics (noise): -30 dBc
    Non-harmonics (noise): -60 dBc
    Modulation: AM, FM, Phase

    What am I going to do with this unit? Well besides confirming that my Kenwood TS-530S is in tune, I’ll also be able to test out the HAL ST-6 and use it to develop the software I need to successfully receive RTTY messages with my vintage computers.

    What is SCELBI’s MEA

    October 21st, 2014

    Like so many other things in the SCELBI world, it’s best to let the creators describe it for you.


    Here is the cover of the manual, which can be found at

    SEA cover page

    SEA cover page

    This development environment, which was available in 1975, was quite an achievement for the time. The environment was “robust” enough that Mark Arnold used it to develop SCELBAL. Few other “personal” computer systems available in 1975 had such capabilities built in. For instance, Microsoft BASIC for the 8080/Altair was developed in emulation on a PDP-10.

    Also at is a intel hex file of the contents of the PROM card. This version of the contents was painstakingly reconstructed by Mark Arnold from an object listing that was sent from Nat Wadsworth to Mark when Mark started experiencing problems with the EPROMs on his system back in the old days. It’s very fortunate that Mark saved this listing.

    Start of MEA Listing

    Start of MEA Listing

    The listing was just a raw dump and where it was folded the data was illegible. Mark and Cameron Cooper managed to get MEA up and running in emulation and used the emulator to help reconstruct the missing data, so they believe the hex file at is correct.

    MEA listing with missing line

    MEA listing with missing line

    The version they have, is set up for the TTY interface. So far, we haven’t been able to find a surviving version of the oscilloscope drivers that would replace the TTY drivers on page 76. I think it’s rather unlikely at this point that we will be able to find the oscilloscope version, so that version will most likely have to be rewritten from scratch.

    We have the TTY version of the MEA program and I have already done the TTY interface card, so we are getting close to having reconstructed a complete SCELBI 8B running MEA. After completing the PROM card, my next efforts will be to do the cassette interface, which will allow running the MEA system as it was intended on real hardware.

    In order to get MEA working in my OS/X emulator, I’ll need to enhance the terminal support to act more like a real TTY as CR and LF are separate functions and I’ll also need to figure out how to support backspace. I also intend to add cassette interface emulation support to my emulator to allow complete support of MEA in emulation.

    New Toy

    October 17th, 2014
    Kenwood TS-530S

    Kenwood TS-530S

    This is another new toy of mine. It is a early 80s vintage HF transceiver that will be used as critical piece of the new aspect of my Vintage Electronics Hobby that was previewed by a post showing another device. This Kenwood TS-530S was purchased as working with new tubes. Like many things on ebay, the reality of the condition wasn’t quite up to advertisement. First power up revealed an issue with intermittent operation. Investigation on the web shows that there are frequent problems with the band switch with these units. I found a couple of tutorials online and preceded to tear it apart.

    Band Switch

    Band Switch

    Though I was a bit intimidated at first by the number of discrete components, the more I worked on pulling this device apart, the less concerned and more intrigued I became. The red arrows show the 7 boards that contain wipers and contacts that are rotated by the bandswitch. I pulled each of them out and checked for connectivity in each position. I found a couple of the wipers were not making any contact at all. I also smelled what I thought probably was tuner cleaner, so someone probably already tried to rectify the issue by cleaning contacts, but based on what I found, that approach had no chance of success. I corrected all the issues that I found and re-installed everything and now it appears the bandswitch probably is working correctly. One thing I did in addition to the normal instructions was measure each of the spacers with a dial micrometer so I was sure I could replace them correctly, should I accidentally mix them up. In case someone else has an issue on a TS-530S, the measurements of each spacer, starting from the front are .1″, .6″, .6″, .2″, .25″, .5″, .35″, .2″, .25″, .15″, .2″, .2″. I was a bit surprised that the measurements of this Japanese made device were in thousands of an inch, but maybe that is because PCB layouts are frequently done in that measurement system.

    I’m not 100% sure that all is well. I haven’t done any transmitting and I decided I need to align/recalibrate the entire transceiver before declaring success and moving on. I have most of what I need to do this, but I do need to build a dummy antenna load and find a signal generator. Oh boy, an excuse for more gear. Stay tuned for new adventures in this new aspect of my vintage electronics hobby.


    Reproduction SCELBI 8B now running SCELBAL

    October 11th, 2014

    This has been a very long time coming and I’m super excited to see it finally running.

    Here is a very poor quality video of it in action.

    Note that the versions of SCELBAL found on the net require 12K because they include all the available features and options. In order to run in a 8K system, the array feature is going to have to stripped out.


    October 11th, 2014

    I’m calling a SCELBI 8H that includes a 4K memory card from a SCELBI 8B a SCELBI 8H-B. See the original 8H-B here.

    Attaching a single 4K memory card to an 8H is easily done because of the way that SCELBI memory cards are addressed. While reading the following description, keep in mind that on a SCELBI, a bank of memory is considered 256 bytes.

    On a SCELBI 8h, there are 4 bank select lines connected to each slot for a total of 16 bank select lines. This provides addressing for 4 banks or 1K per slot and 16 banks or 4K for the entire system. The are 4 bank select lines connected to each of the 4 slots at different points as can be seen in this image of part of the 8H backplane.

    8H backplane bank selects

    8H backplane bank selects

    On a SCELBI 8H 1K memory card, each of the four banks available on the 1k card, is connected to the backplane at four different points. In the picture below, the line for the first memory bank on that card is highlighted in green.

    1KSRAM 1st bank select

    1KSRAM 1st bank select

    Depending upon which slot the card is plugged into, it will pick up the 4 bank selects for that slot, thus automatically providing a different address range for each slot, without requiring extra decoding logic on a memory card.

    The SCELBI 8B memory design is a little different in that the memory expansion card decodes 16 banks for each slot (4k) and a total of 64 banks (16K) for the entire system. This image shows the 64 bank select lines going to the 4 memory slots on a SCELBI 8B backplane.

    8B memory selection

    8B memory selection

    The 4K memory card is also different, with the 16 bank lines all feeding into the on board circuitry separately.

    4K memory selects

    4K memory selects

    This design also requires extra complexity on the memory card. The 16 bank selects on the back plane must be demultiplexed into 4 chips selects, each of which selects one of the four rows of memory chips.

    So how do you connect a 4K SCELBI memory card to the 8H? A few of you may have already deduced how to do this. You simply jumper all 16 banks selects available on a 8H backplane to a single slot, making sure you leave the other slots empty. This still leaves you a 4K system memory capacity, but will significantly reduce the cost of creating a 4K SCELBI 8H.

    The SCELBI 8B memory addressing architecture is unique in my experience. I think it was deliberately designed to allow use of a single 4K memory modules in a SCELBI-8H. Perhaps Nat and Bob were considering a cost reduced 5 slot SCELBI 8H backplane that would take advantage of this architecture.