The parameter bank consisted of 3 banks of 18 rows of 16 thumb-wheel switches installed in a sliding tray. Each hardware setting of the spectrometer was determined by reading the first two thumb-wheel codes of each row. If this reading matched the set analytical program on the spectrometer front panel, then the following thumb-wheel codes of that row were read and hardware settings were made to the spectrometer. This coding included a measurement time.
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| Example of BCD thumb-wheel switch |
When the measurement analysis time of that row was completed, the electronics would then move on to find the next analytical program match. If nothing was found after checking all rows / banks, the analysis would then be considered complete and the automated reading process stopped.
The problem with the thumb-wheel switches was poor contacts within the switch due to accumulation of dust as the switches were mounted face upwards. A second problem was the cost to replace the switches. These were specially made BCD coded and not the same "coding" design as other manufacturers. Added to this the spectrometer had reached its "end-of-life" service period (some 15 years of service) and there was a shortage of spares for this instrument. The customer at that time did not have a budget to replace this instrument with a more modern instrument and the analytical department were tasked "to try keep the instrument alive".
After much searching for spares, detail was received from the analytical department of PHILIPS Australia of an upgrade that was done in their country as they had experienced the same problem.
Based on their ideas, it was locally decided that a replacement system be locally developed and tested. We locally had the microprocessor training / skills needed. I took on the task as I was the senior technician at that time.
The replacement system design was based on the use of a Z80 microprocessor training unit and it just so happened that the MicroProfessor MPF-IP was launched as a training unit for students studying electronics. A number of these units were purchased and the purchase included a set of the "optional" development circuit boards which were an EPROM programmer, RS232 interface, a thermal paper printer (5cm width), and an electronic sound / voice synthesizer card.
The problem with the thumb-wheel switches was poor contacts within the switch due to accumulation of dust as the switches were mounted face upwards. A second problem was the cost to replace the switches. These were specially made BCD coded and not the same "coding" design as other manufacturers. Added to this the spectrometer had reached its "end-of-life" service period (some 15 years of service) and there was a shortage of spares for this instrument. The customer at that time did not have a budget to replace this instrument with a more modern instrument and the analytical department were tasked "to try keep the instrument alive".
After much searching for spares, detail was received from the analytical department of PHILIPS Australia of an upgrade that was done in their country as they had experienced the same problem.
Based on their ideas, it was locally decided that a replacement system be locally developed and tested. We locally had the microprocessor training / skills needed. I took on the task as I was the senior technician at that time.
The replacement system design was based on the use of a Z80 microprocessor training unit and it just so happened that the MicroProfessor MPF-IP was launched as a training unit for students studying electronics. A number of these units were purchased and the purchase included a set of the "optional" development circuit boards which were an EPROM programmer, RS232 interface, a thermal paper printer (5cm width), and an electronic sound / voice synthesizer card.
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| MicroProfessor MPF-IP |
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| RS232 development card |
Code for the customer system was written using a Z80 machine code compiler software package that was available for a SHARP MZ80B computer at that time. This was a computer that I purchased about a year before this project. I was at the time busy learning about programming 8080, 8085 and Z80 microprocessors. I still have this computer and have come across a number of websites where information is still been requested. It had 32k ram memory which I increased to 64k with "wire-wrapping" technique, it uses a built-in audio cassette tape unit for loading / saving programs as floppy drives were not yet available. A year later IBM released its first computer with Microsoft DOS, floppy drives, 10Mb hard disc drive and this is now history.
Time has moved on and I have gained a lot more experience in computers, software and many other topics. I am now working for myself and my company name is "Retirement".
Since becoming a licenced Amateur Radio operator, I joined / became a member of a club in a neighboring town. At one of their club meetings there was a request for some assistance in programming some frequencies of some "old radios" which would be used as APRS receivers. APRS audio data from radio operators in the area would be received by these radios and then be processed using a PC. The processed information would be forwarded by the PC to an APRS website via Internet. The website would receive an upload of the decoded APRS audio data and then display the GPS location of the person/s sending an APRS code on a Google street map. A very interesting radio application.
I was told the "old radios" had "PROMS" that needed to be programmed.
Well, I decided to assist and found I had to go back in time to some of my past skills. This required some serious reading however it all slowly started to come back in my mind. Found my EPROM programming unit and all the other items to go with it. First had to replace the rubber belts in the audio cassette unit and then sort out the recording switch.
I then tried to capture the data as audio file using a computer sound card however this process had its problems. The sampling speed that was used for "digital capture" of an analogue audio signal created some interference resulting in loss of data bits. Other speeds were tried and problem remained.
I finally decided to try the KISS approach (Keep It Simple Simon). There was sufficient spare RAM (200 bytes) in the MicroProfessor MPF-IP memory to write some Z80 software code. This code was created using a Z80 compiler software package obtained via internet. Similar to the one I used for my SHARP MZ80B however worked in Windows XP environment. Very nice package as it included a debugger facility. The code was written for recording / reading back EPROM data to / from my desktop computer. Data was saved / read as a simple text file using the MPF-IP RS232 interface and RS232 interface of the desktop.
I chose the "INTEL Hex" transfer format as it provided a software mechanism for the checking of successful transfer / storage of strings of data on both the processor and desktop computer. Data capture on my desktop was done using a receiving program written using the software package "BASIC".
The "INTEL Hex" method, and derivations of it, are still used in modern day computer communication.
Once successful and fully tested, a new EPROM for the MicroProfessor MPF-IP was programmed and then installed. The function change simply replaced use of an audio cassette as a storage device.
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| SHARP MZ-80B |
Time has moved on and I have gained a lot more experience in computers, software and many other topics. I am now working for myself and my company name is "Retirement".
Since becoming a licenced Amateur Radio operator, I joined / became a member of a club in a neighboring town. At one of their club meetings there was a request for some assistance in programming some frequencies of some "old radios" which would be used as APRS receivers. APRS audio data from radio operators in the area would be received by these radios and then be processed using a PC. The processed information would be forwarded by the PC to an APRS website via Internet. The website would receive an upload of the decoded APRS audio data and then display the GPS location of the person/s sending an APRS code on a Google street map. A very interesting radio application.
I was told the "old radios" had "PROMS" that needed to be programmed.
Well, I decided to assist and found I had to go back in time to some of my past skills. This required some serious reading however it all slowly started to come back in my mind. Found my EPROM programming unit and all the other items to go with it. First had to replace the rubber belts in the audio cassette unit and then sort out the recording switch.
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| MPF-1P EPROM programmer |
I then experienced some problems getting the MicroProfessor MPF-IP and audio cassette unit to talk to each other correctly. The audio tapes were problematic as I could not successfully record / read back 2 kilobytes of data from an EPROM dump !!!
I then tried to capture the data as audio file using a computer sound card however this process had its problems. The sampling speed that was used for "digital capture" of an analogue audio signal created some interference resulting in loss of data bits. Other speeds were tried and problem remained.
I finally decided to try the KISS approach (Keep It Simple Simon). There was sufficient spare RAM (200 bytes) in the MicroProfessor MPF-IP memory to write some Z80 software code. This code was created using a Z80 compiler software package obtained via internet. Similar to the one I used for my SHARP MZ80B however worked in Windows XP environment. Very nice package as it included a debugger facility. The code was written for recording / reading back EPROM data to / from my desktop computer. Data was saved / read as a simple text file using the MPF-IP RS232 interface and RS232 interface of the desktop.
I chose the "INTEL Hex" transfer format as it provided a software mechanism for the checking of successful transfer / storage of strings of data on both the processor and desktop computer. Data capture on my desktop was done using a receiving program written using the software package "BASIC".
The "INTEL Hex" method, and derivations of it, are still used in modern day computer communication.
Once successful and fully tested, a new EPROM for the MicroProfessor MPF-IP was programmed and then installed. The function change simply replaced use of an audio cassette as a storage device.