Bridgeport Series 1 CNC problems

"DoN. Nichols" fired this volley in news: snipped-for-privacy@Katana.d-and-d.com:
MC68000.
LS
Reply to
Lloyd E. Sponenburgh
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You can get most of those computers together for under $1000.00 total by now -- unless you are including some mainframes, where the metal scrap value is higher. :-)
Enjoy, DoN.
Reply to
DoN. Nichols
Intersting. That was what powered my first unix box at home. A Cosmos CMS-16/UNX. 8 MHz MC68000. (And later computers at home with the MC68010 and MC68020.)
That would certainly get room for more "feet" of memory (measured in length of punched tape used to store the program, and 10 bytes/inch, or 120 bytes/foot. A lot of the LSI-11's address space was taken up with ROMs for the OS, and not much space left to expand. IIRC, the quad-wide LSI-11 could not address more than 32 K words (64 K bytes) total. The MC68000 could access up to 16 MB. So, assuming that the firmware expanded to a full 64 K bytes (added features), and perhaps to 128 K bytes (less efficient coding or more on-screen prompting text), that still leaves most of the 16 MB for part programs. O.K. 512K for the firmware, and another 512K for the memory mapped I/O ports to leave 15 MB for the part program would translate into 131,072 "feet" of memory, or about 24.8 *miles*. I never did bother measuring how much punched tape a 10-1/2" reel could handle, but I would be surprised to see it holding more than a mile of tape. So there would be no need to fill the entire available address space with RAM. :-)
Oh yes -- and to put it in perspective, my Emco-Maier Compact-5/CNC lathe runs from a single Mostek 6502 -- again 64K bytes maximum address space and a much less capable CPU.
Thanks, DoN.
Reply to
DoN. Nichols
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O.K.
Well ... have you been able to compare the behavior of *all* axes with similar motion commands? Each axis has its own power supply (a single phase from a three phase transformer) and has its own saturable reactor, so you could perhaps be measuring a different axis than you are exercising.
You can command each axis to move a specified distance at rapid move rate from the control pod. I forget the sequence of commands, but you select the axis with a three position rotary switch, the distance 1", 0.1" 0.01" or 0.001" by another rotary switch, and then command the move by pressing one of those switches as a pushbutton (which it can be as well as a rotary switch). This is in manual mode, obviously. And it does not require loading a program.
Does yours have the punched tape reader? Do you have access to something which will punch the tape -- a Teletype ASR-33 will do among other things, since the codes used are ASCII.
Well ... the monitoring really needs a test program performing the moves. You'll find the saturable reactor acting as a reactor at a stop, or at a certain range of slow speeds, but as the step rate gets above a certain threshold, it will go to the saturated mode so you get more voltage from the power supply to the driver transistors.
If yours is a new enough machine, you can probably unplug the axes stepper motors from the hinge-out heat-sink panel (IIRC, down near the bottom), while the really early ones require removing wires one at a time from a terminal strip (again IIRC).
My machine is being converted to servo motors with the EMC program to control it (and I'm hung up on making the replacement belt housing and motor mount for the Y axis). The stepper machines have a recess in the knee for the stepper motor, but the servo motor is much longer and has to pass beside the knee instead, so an angled belt housing and mount instead of straight up and down.
Less than 1K byte. :-) As I just mentioned in another branch of this thread, a "foot" is 120 bytes on punched tape. AFIK, they *still* rate them in feet, even though they don't have punched tape readers any more. :-)
I can't go down and check anything on what is left of mine because I'm in the recover phase from my first cataract surgery, and under rules of "don't pick up anything over twenty pounds". Then there will be a short while when I can pick up heavy things again, and then I'll go in for the second eye. (FWIW, the improvement in the first eye is *amazing*. I had not realized how much I had lost.
Enjoy, DoN.
Reply to
DoN. Nichols
I taught myself assembler on a MC68008 machine and thought it was great, a bit later we covered it at college where we were taught 6502 assembler, that was painful going from byte, word, and long word instructions to byte. For some time I would occasionally use Motorola op codes and wonder why it wouldn't assemble. Did some useful coding on the 6502 but it was arcane compared to the MC68000. The article published by Motorola about the designing of the MC68000 made interesting reading.
Reply to
David Billington
David Billington fired this volley in news:49c6bafb$0$16164$ snipped-for-privacy@news.zen.co.uk:
Heh! The 6502! The Commodore-64! An associate and I wrote the DOS and accessories for the Lt. Kernal hard-disk DOS for the C64 and C128.
LLoyd
Reply to
Lloyd E. Sponenburgh
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And being stuck with index registers which were only 8-bits long, and a stack pointer which was stuck in the second 256-byte page of memory.
I much preferred the 6800, which had true 16-bit index registers, and a true 16-bit stack pointer so you could put the stack wherever you wanted.
The 6809 later had instructions for treating the two 8-bit accumulators as a single 16-bit one, as well as indexing off both stack pointers, both index registers, and the program counter, making position-independent code a lot easier to write. (And OS-9 *required* position-independent code as well as reentrant code.)
:-)
Take a look at the 6809 sometime. It is not a 68000, but is more of a 16-bit processor than the Intel 8088 was. :-)
Enjoy, DoN.
Reply to
DoN. Nichols
Gentlemen
The problems are resolved.
The replacement of the blown fuse, together with manual cleaning and lubrication of the X axis screw and the same with the Z now has the machine running rapids on all axes.
The machine has obviously sat for sometime.
Thanks for all the input.
Richard
Reply to
Richard Edwards
Great!
And now it is going to be used again.
You're welcome, and good luck, DoN.
Reply to
DoN. Nichols

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