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Author Topic: Your latest purchase  (Read 107152 times)
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nr Bundaberg, Australia
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Only $11, amazing. I might grab a couple myself.

@CB
Totally unbiased, honest.

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Rob
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Rob Gray aka the GRAYnomad www.robgray.com

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I couldn't pass up one of these:

http://shop.evilmadscientist.com/productsmenu/tinykitlist/375-dcii


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« Last Edit: December 05, 2012, 02:01:43 pm by PapaG » Logged

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Since I believe the Motorola 6809 was the best 8-bit microprocessor ever made, I ordered a couple while they are still available. I ordered a couple of 6821s (PIA) and 6850s (ACIA) while I was at it. I need to find some compatible SRAM and some program storage memory that is relatively easy to program as I have no idea where my EPROM programmer has gotten off to. Any recommendations welcome.
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Does anyone remember the "computer" from 70's made out of long plastic switches and wires and lights?  You stuck pre-printed paper in the plastic in front of the lights.  You stuck wires in the holes.  Each lever switched like 8 switches which were wired in parallel.  I didn't know who else to ask this question to, so I thought I'd try here.  It's related to the post about the gravity powered computer above.
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Wafer connectors from dipmicro.com
Many sizes to play with, yeah!
The kit did't include the box.


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nr Bundaberg, Australia
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6809 was the best 8-bit microprocessor ever made, I ordered a couple while they are still available.
I used to program on a 6809 as well. How about we make a retro dual processor (09/Z80) board smiley

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compatible SRAM and some program storage memory that is relatively easy to program as I have no idea where my EPROM programmer has gotten off to. Any recommendations welcome.
There's plenty of SRAM around these days that will work. As for the EPROM, maybe use flash or just battery-back the SRAM. You could build in a modern micro to act as a programmer.

Another idea is to have an modern micro actually serve the EPROM data.

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Rob
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An ABM Ultrasonic Industrial sensor (used for measuring fullness of large tanks, I think),  .7 - 20ft range, absolutely no idea what to use it for, but won the auction on a 99 cent bid with free shipping. 4- 20ma current loop it says, I'll have to research it a bit.

I love oddball stuff....
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6809 was the best 8-bit microprocessor ever made, I ordered a couple while they are still available.
I used to program on a 6809 as well. How about we make a retro dual processor (09/Z80) board smiley

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compatible SRAM and some program storage memory that is relatively easy to program as I have no idea where my EPROM programmer has gotten off to. Any recommendations welcome.
There's plenty of SRAM around these days that will work. As for the EPROM, maybe use flash or just battery-back the SRAM. You could build in a modern micro to act as a programmer.

Another idea is to have an modern micro actually serve the EPROM data.

______
Rob

I would certainly be willing to work on the 6809 half. smiley I had a Z80 CP/M machine (Big Board) but didn't do much hardware development on the Z80. As I recall though, it was very Motorola like at the bus level so it would be a good match.

I have already started thinking about the memory. Battery backed ram might be the way to go. On the other hand I was thinking about building a programmer for EEPROM that ran off my Raspberry Pi. I have already compiled and tested a cross assembler that runs nicely on the Pi and I thought since the hex files would already be on it it would make sense to use it for the programmer.

How would you propose serving the EPROM data via micro?
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An ABM Ultrasonic Industrial sensor (used for measuring fullness of large tanks, I think),  .7 - 20ft range, absolutely no idea what to use it for, but won the auction on a 99 cent bid with free shipping. 4- 20ma current loop it says, I'll have to research it a bit.

I love oddball stuff....

If it's functional that will be quite a buy as it appears to be an industrial unit and probably cost well north of $1K. First thing to determine if it's a simple loop wired '2 wire transmitter', meaning it has only two terminals to wire to. If so a simple current loop wiring would be a +12 to +24vdc power supply to positive terminal of unit, - terminal of unit to 150 ohm resistor, other end of resistor to negative of the 24vdc power supply. You can then read the analog measurement range as a +1 to +5vdc voltage across the resistor. This is easy to interface to a arduino analog input pin, just wire a common ground from the 24 volt negative to an arduino ground pin and the other end of the 150 ohm resistor to an analog input pin.

Might this be the datasheet? http://www.abmsensor.com/pdf/2010092wire-sanit.pdf


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Yep, looks like it.  I believe it is the version without the RS-232 or 485 interface, it's NOS surplus from a PLC reseller. 

Should arrive tomorrow or Wednesday..
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Does anyone remember the "computer" from 70's made out of long plastic switches and wires and lights?  You stuck pre-printed paper in the plastic in front of the lights.  You stuck wires in the holes.  Each lever switched like 8 switches which were wired in parallel.  I didn't know who else to ask this question to, so I thought I'd try here.  It's related to the post about the gravity powered computer above.

That doesn't ring any bells at all!
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nr Bundaberg, Australia
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As I recall though, it was very Motorola like at the bus level
IIRC (it's bee a few years) there were a couple of fundamental differences, the 68xx chips had a R/W signal and a CS signal and everything is memory mapped. The Z80 has separate WR and RD signals plus separate select signals for memory and IO.

However it was easy to make them compatible with a couple of AND gates or whatever.

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I was thinking about building a programmer for EEPROM that ran off my Raspberry Pi.
Unless you plan to remove the chip for programming you have to dual port the memory chip, easy enough but adds several chips. I had an EPROM emulator on the market that plugged into the EPROM socket and used SRAM with the dual porting added.

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I thought since the hex files would already be on it it would make sense to use it for the programmer.
Easy, if you have a valid HEX file you can easily load it into the target memory subject to the above.

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How would you propose serving the EPROM data via micro?
Well these old chips weren't very fast eh? Maybe connect the AVR (or whatever) up with pins the same as an EPROM and monitor the CS/RD signals, when you see an active select you use the address to index into an array and provide the data.

This was proposed by somebody here quite some time ago, originally I poo-pooed the idea but it may have legs. Especially if you can control the target CPU's clock.

Adding dual-ported RAM would be easier but uses a few chips, this idea only needs a single chip.

Or build an FLASH emulator for development and drop a chip in when finished, just like we used to do but without the UV light smiley

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Unless you plan to remove the chip for programming you have to dual port the memory chip, easy enough but adds several chips. I had an EPROM emulator on the market that plugged into the EPROM socket and used SRAM with the dual porting added.
I had though to remove the chip for programming but I see there are I2C bus expanders with tristate outputs so I'd probably use those to dual port the memory.
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Well these old chips weren't very fast eh? Maybe connect the AVR (or whatever) up with pins the same as an EPROM and monitor the CS/RD signals, when you see an active select you use the address to index into an array and provide the data.

This was proposed by somebody here quite some time ago, originally I poo-pooed the idea but it may have legs. Especially if you can control the target CPU's clock.
The NMOS version of the 6809 couldn't tolerate a stopped clock but you could certainly stretch it. If the AVR supplied the clock, it would be pretty easy to do what you suggest, I imagine. An interesting exercise.
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Adding dual-ported RAM would be easier but uses a few chips, this idea only needs a single chip.
Albeit one with lots of I/O. smiley
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Or build an FLASH emulator for development and drop a chip in when finished, just like we used to do but without the UV light
I had two big EPROM erasers running full time. I'll never forget the smell of conductive foam exposed to UV light! smiley
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nr Bundaberg, Australia
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I'll never forget the smell of conductive foam exposed to UV light!
It's funny how you remember such things.

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I had two big EPROM erasers running full time.
That's why I built the emulator, got sick of swapping chips.

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Rob
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I'll never forget the smell of conductive foam exposed to UV light!
It's funny how you remember such things.

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I had two big EPROM erasers running full time.
That's why I built the emulator, got sick of swapping chips.

______
Rob
Memories are coming back. I, too, had a ROM emulator later on. Very handy. smiley
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