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Fri, 10 Apr 2009
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Years ago, I built a simple PIC programmer that I use for programming the micros I use for my various projects. Recently, I was playing with a simple PIC18F4455 based board that had FORTH in rom. Just my cup of tea. Unfortunately, the programmer let me down by not correctly writing into the EEPROM. Having consulted the Microchip programmers manual, I have modified the devices.cfg file that is used so it correctly reads and writes EEPROM. Attached is a zip file containing the software, as well as the schematic for the programmer. It is placed here as a backup in case the originals go away. If you are the rights holder, and you want them gone, then just let me know
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Having said many months ago that I would post the doco and binaries online - and having now received 2 requests in as many months, I have decided to upload them here. Attached to this post are copies of the 65FRx Development ROM (for a 2764), and a PDF file containing the original articled that described the forth board - Which I purchased from Energy Control in the mid 80's.
One minor Note - The rom I have here is v1.5, and there is an anoying issue with the floppy disk routines - prior to use, the disk buffers are located in a memory area that is outside of real RAM on the RSC board, therefore you MUST execute the following command before any disk routines will work. HEX 1800 MEMTOP If you are the copyright owner, and you are sadened that I have posted this information online, then I would appreciate it if you were to email me. Happy to remove the data - but, please keep in mind that I suspect that this is probably the final resting place for this information, and I am confident that there are individuals who would appreciate it if you were to make it available.
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After what seems like forever, I have finally obtained all of the silicon and associated hardware to build my very own ELF computer. What is an ELF you may ask - Well - it is a single board trainer that first appeared ina magazine called "Practical Electronics" in about 1976. It is based on a RCA microprocessor called an 1802, has about 256 bytes of memory, and uses switches to manipulate the address and data busses to load software. I first saw one about 15 years ago, and decided that it simpy wasn't practical to obtain the parts to build one - Well, thanks to the power of e-bay I obtained the hex displays, memory and CPU. A bit of scrounging around in my various parts bins nettwe me the rest of the components I needed, and a couple of evenings of effort later, and - Here it is. My first program was a program to turn on and off the 'Q' LED based on the state of the input button - Gosh, Wow - Gee wizz. Hmmm - Can I get an OO language for it
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A while ago, I completed a PS/2 Keyboard logger using a simple PIC 16F84, and a NVRAM chip. It was a ton of fun to complete, and still needs a little work. Here are a couple of photos of the device. All it needs now is some heatshrink to protect it. The next step, is to do the same task for USB, but I suspect that it will be more complex, as the USB bus is quite a bit faster than the PS/2 Bus.
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Hmmm,
I just saw a new toolcase that turned up at work. It was a small black binder, containing an assortment of parts that would be usefull for working on PC equipment. The best bit was: ----- That it contained a DIP insertion, and DIP extraction tool, kind of like those we would have used back when memory was in the form of a 16 pin DIP package. Gosh !!!! I haven't seen those parts in years. The bit that scares me is that somewhere in China, a factory is producing these things in bulk.. When Will IT END (tm)..
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What an old machine! My first job was a summer job working for the School of Biochemistry at the ANU, writing a program for a Toshiba T-300 that controlled a Microplate reader, read the results from the plates, and plotted them. All the code was written in Basic. Essentially, the researcher would fill a tiny sample plate that contained 12 rows of 8 wells with stuff, and the machine would robotically move each cell (under computer control) to an absorption measurement device that would record the transmission characteristics of the sample at a specific wavelength. The data would be shipped off to a computer, and the process repeated for 96 cells. I don't remember the chemistry of what was occuring, but I do remember that the team ws trying to find a mechanism to seperate X and Y chromosome markers in Cow semen, so that a farmer could purchase a test tube containing only cows, instaed of bulls. Interestingly, this research was in 1986, and I saw on the news recently that a major commercial breakthrough had occurred and this technology is now commercailly viable. As a summer project, it was pretty cool, and the most interesting part of the problem wasn't writing the serial code to do the controll, instead, it was writing the plotting software to deal with abritrary scales on the data. The job was finished, and the final payment was a cheque to the value of a Shiny new TRS-80 Model 100 (with 32K of RAM). The ANU could not purchase a machine for me due to asset control problems, but they could make out a cheque. I remember depositing the cheque in mu parents bank, and marching into the Tandy shop, and having to attract the attention of the sales guy, as I surely wasn't really going to make a purchase.(Remember I wasn't 18 yet...) It wasn't long before I discovered that the internal modem only worked in the USA (Using Bell 103 tones, instead of the CCITT standard we use here). I spent the time to understand how the op-amp based bandpass filters worked to calculate new resistor values for the CCITT tones. The mod to the modem chip was trivial (change the mode pin from Bell to CCITT, but the bandpass filters caused me grief for a couple of weeks. The second mod was to allow the device to supply (or recieve power) along the serial cable (using pin 13 from memory), so I didn't have to carry around extra cables. And finally, I modified the light pen interface on the side to accept an Atari joystick, and replaced the proprietary Expansion ROM connector to allow me to use normal JEDEC standard parts. Those were the days - You could get the rom dumps, and make the changes yourself. I have also found my TRS-80 PC1 - Never did any hardware hacking with it, as the doco wasn't available, but have found that he full doco is available now. Just don't have the time available now days!
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I thought I would put up a couple of pictures of a computer system I constructed in about 1987. A company in Queensland called 'Energy Control' distributed a single board development card based on a Rockewll FORTH chip (65F11 / 65F12). Essentially the development system had all of the required support components to support develpment (even a FDC). I constructed my unit is a small enclosure, and originally installed a 720K 3.5" drive that I borrowed from tech. Tech wanted their drive back after a couple of months, so I installed a 80 track 5.25" drive. 4 years ago, I decided to replace the 5.25" drive with a 3.5" unit. The 65F11 is an interesting device. It had a 6502 core, and all of the forth primitives in mask rom, as well as I/O controllers all on chip. Many fun hours were spent developing forth code on this system, and I eventually used it to develop my multi radio controller as a tech project. It used the 65F12, which had tons of I/O. I still have all of the doco rom Rockwell, as well as the binary images for the Rockwell forth development ROM, If anybody is interested, I'll post them online.
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I was cleaning the workshop the other day, and found my old acoustic coupler from the mid 80's. Those were the days, collecting dial up numbers for systems that would answer. The cut and thrust of guessing passwords, and trying standard admin accounts (especially on VAX boxes.) From memory, I received my first formal warning when the system admin of our school looked at the teletype records that were printed whenever anybody dialed up (yep, I didn't know about that *early* logging technology.) All at the blistering speed of 300 baud. At least it was battery powered, so the whole thing was portable. Those of you with a clue may ask 'But the TRS-80 Model 100 was well known for it's internal modem... Why did you have to resort to an acoustic coupler? ' Well, 1) Originally the internal modem of the TRS-80 was set for Bell 103 tones, not CCITT (The component changes hapened later on, and yes, it worked a treat, and 2) The acoustic coupler worked a treat in public phone booths..
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I saw an interesting thing this morning when an authorised Dell service engineer turned up to do some waranty work on one of the stuffed laptops. The laptop in question had a faulty DVD drive, and the PCMCIA eject button had fallen off. We logged the service call yesterday, so the service is extremely prompt, and the tech that arived was friendly enough. He had all of the appropriate spares. The faulty laptop was then disassembeld in it's entirety to replace the motherboard, on the coffee table... WITH NO ANTI STATIC PRECAUTIONS. The tech was wearing a large wollen trenchcoat, and was probably charged (it's a dry environment here..). When I were a lad, we used wrist straps, and everything was grounded. Either (1) things are no longer static sensitive, or (2) he was slack. We should know in a couple of months. |
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In August 1981, the IBM PC was launched into the unsuspecting marketplace. The major claim to fame of the design was that it was tried and tested (remember that the 8088 was released in about 1978), and it is probably fair to say that the design on the IBM PC was extremely conservative, as it was a rapid development project to provide IBM with the capability to compete against Apple Computer.
In the olden days, memory was a big deal. It was expensive and complex to manage in hardware. The IBM PC did not use the latest available memory technology when it was introduced; instead, it used 4116 chips from about 1974. 1974! I hear you say. Yes, the original IBM motherboard had the capacity to be shipped with 16Kb installed on the motherboard (expandable to 64Kb), using exactly the same memory chips used in the TRS-80 Model 1 from 1974. The original motherboard could support 64K on the motherboard, and could also support three 64K expansion memory cards, providing 256Kb in total. Remember that in that era, 256Kb was a big deal . the motherboard also had a cassette interface to allow data to be recorded onto tape. Because the IBM PC used 4116 (16 Kbit x 1 bit) dynamic memory devices, a -5v power rail was required to provide a bias current for the memory chips. A suitable power supply was specified that provided +5v, -5v, +12v and -12v for the system to cater for the memory requirements. Here is where it gets silly - We stopped using the -5v rail after 4164 chips (64kb x 1 bit) were common, but the brain dead, thoughtless, engineering involved in duplicating the IBM PC didn.t notice. Modern ATX power supplies still provide a -5v supply rail for these obsolete memory devices. But what about analogue cards you may say? In those cases, they use a -5v regulator off the -12v rail. All of those components being installed into boards, to supply a function that is not required. All because the original design was .conservative., as IBM wanted to get to market quickly! What a waste! |
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I have just loaded up the RS485 controller PCB I designed a couple of years ago.
Here is the link http://www.drj-electronics.com/projects/articles/4in-4out/index.html |
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Cool,
An IMSAI 8080 is going on Ebay. Looks like quite a nice system: http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=8804809289 It will be interesting to see what it goes for. Traditionally, these fetch USD$2500+ on US auctions. UPDATE: Well, it's been a couple of days and nothing has hapened on this auction. Either (1) nobody knows, or (2) there are many people waiting in the wings to snipe at the last second Final - It sold for slightly over $1500 AUS - Very surprising - The Australian market is quite diferent to the US. |
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I have come across an interesting story being run by the BBC that indicates that the EU will be mandating battery recycling.
The flow on effects on this are very interesting. Manufacturers will be required to ensure that batteries are accessible to allow removal for recycling. This potentially means that they will then be replaceable, so it may wipe out the throw away attitude. While that would be nice, I suspect that the manufacturers will design the battery removal facility such that it will damage the casing, and make re-assembly impossible. Let's wait and see. The story is here http://news.bbc.co.uk/2/hi/europe/4969544.stm |
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I have also updated the temperature datalogger.
The circuit diagram is now there. http://www.drj-electronics.com/projects/articles/templog/index.html |
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I have updated the project page for my PIC based LED Dice project.
It can be found here. No more dead links. http://www.drj-electronics.com/projects/articles/leddice/index.html |
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Hmmm Having spoken to Icom, they are unable to get me a new microprocessor for my stuffed IC-2SAT. They do, however, have a replacement 'logic' PCB - Logic Unit PCB Assembly 8888800115 in stock $270 I have emailed them, suggesting that the $270 is slightly outlandish, given the fact that a new dual band radio is available for not much more than that. They are yet to respond.... On a happier front, checkout the http://www.alinco.com web site. Their devices dont cost that much, and sure are feature packed. I suspect that I may give up, and part with about $200 or so shortly, just to secure a decent frequency agile UHF handheld. My Motorola HT220 is crystal bound, and it appears as though the Canberra Ginin repeater is no longer on 438.525. |
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Lots has been hapening that I haven't entered. So the next few entries will be out of order. I purchased an Icom handheld cheaply the other week. It was sold as being faulty. It arived on Friday, and I have spent the last couple of nights working out the problem. I have downloaded the service manual (for the IS-2SET) which is equivalent. So far:- 1) I am getting older. The 1mm x 2mm components are very small - tricky dick sold me a really neat magnifier to sort that out. 2) The PSU is shot. The +5V rail drops to 2.4v when it is on. Truns out to be a shorted diode DA114 and Open Circuit Collector on a PNP transistor - 2SB798 in the PSU. I have substituted normal sized components in the short term, and the PSU voltages come up fine. 3) The Microprocessor oscilator is not running. It's either a) The micro is held in reset, b) the micro is stuffed, or c) the ceramic resonator (800kHz) is stuffed. A couple of quick measurements has confirmed that the device is not in reset, so I will work on the last option. - The interesting measurement is the both of the resonator leads (from the micro) are held at approximately VCC...(4.7 and 4.2v). I was expecting one to be high, and one to be low.... 4) Mouser electronics in the US http://www.mouser.com/ is my friend. They have all of the spares in stock. 5) ICOM Australia is not my friend. They came back to me with some very interesting information - They can provide all of the silicon (except the CPU) at only a couple of dollars each. They can not provide a resonator, nor can they sell me a new microprocessor. (Peter - No, I will not develop a PIC controller for it...) Pleasingly enough, they can provide me with a new micro board for a mere $280.00 Hmmmm. Let me see now, what's a new dual band handheld worth...... No.  We will wait for the new parts to get here from mouser. |
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All this working with old handhelds has reminded me that I have a Kenwood TH-205 with a stuffed VHF amplifier brick (M57732L). Unfortunately, that part costs a fortune ($80USD) A quick web search showed that it has been replaced with a new brick called RA08H1317M which is smaller, cooler, etc, etc. I found a NZ Company (http://glyn.co.nz) who will supply them for $20AUS each. Just ordered 2. Wo Hoo, another handheld working |
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I finally have pictures of the Silicon that my sister Suzy designs for a living. She works for the National Telescope, and her most recent toy is a CMOS 400 - 1700Mhz receiver that fits on a tiny wafer. Check it out at: http://www.atnf.csiro.au/people/Suzy.Jackson/NTD_chip_with_match.jpg |
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I spent last night building an antenna as per the instructions in http://www.wireless.org.au/~jhecker/helix/
Hmmm.... It didn't work too well. Further research discovered that the design presented there didn't factorthe dielectric effects of the PVC, and incorrectly labeled the pipe size. 1. I used pressure pipe 2. I used piped marked as being 40mm dia. This was the worst problem, as it's OD is closer to 50mm.... Anyway, I am off to the hardware store with my tape measure to find some pipe that is about 35mm diameter, and we will see where that takes us. I'll connect to your network next door Mikal, just wait!!! |
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Projects - Some of my projects
DRJ-Consulting - A site focused on saving energy. Dougs Word Clocks - I make my own clock that tells the time using words. we Just Dont Talk About That - A site for sharing funny family stories. Megan's weblog Email me at doug@stillhq.com |
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