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RE: [N8VEM-S100:1783] IMSAI/Altair Front Panel Mini project

Hi Leonard,


The SMB see (http://www.s100computers.com/My%20System%20Pages/SMB%20Board/S100%20Bus%20SMB.htm) does some of what you wanted.  It does not have the deposit, deposit next capability, but you can single step, read data and address bus and set a hardware breakpoint (anywhere in the 16MG address space).   Frankly I always found a ROM monitor is easier and more powerful to fill, examine or change RAM. 


The issues with the original IMSAI/Altair front panel boards is they use single shots etc and do not reliably work with bus clocks past about 4MHz.   The circuits will have to be different for 10-12MHz CPU clocks we have in our newer boards.


FWIW I will soon be doing with Andrew a Version II of the above SMB.  It will be better suited for higher speeds, but in particular allow better handling of master/slave switching of multiple different CPU’s on the bus.  (i.e. decode the TMA0*-TMA3* lines).


I considered the deposit/deposit next functions, however the 20 address line switches and up to 16 data line switches would leave little room on the board for anything else.


The only other way is to use a FPGA chip with lots of I/O bits directly to the bus  and a serial connection.  However that to my mind is almost the same as using a Z80 line monitor.










John Monahan Ph.D

e-mail: mon...@vitasoft.org

Text:    mon...@txt.att.net



From: n8vem...@googlegroups.com [mailto:n8vem...@googlegroups.com] On Behalf Of Andrew Lynch
Sent: Friday, August 09, 2013 8:45 AM
To: n8vem...@googlegroups.com
Subject: [N8VEM-S100:1783] IMSAI/Altair Front Panel Mini project


Hi Leonard

Well, interesting you should say that...



We've already designed such a critter.  However it seems to have run into significant technical problems.


I'll let Don Caprio, Rich Cini, and John Monahan get into the technical specifics but as I recall it would require major redesign to be a "general purpose" S-100 front panel.


Maybe it could be done?  There were at least a couple rounds of prototype boards built.  It seems a shame to let it gather dust now though after all the sunk cost and effort that went in to it.  Blood, sweat, and tears (mostly tears at the end...)


I still support the project but it may require some super-human effort to fix it.  Not a challenge for the meek...


Thanks and have a nice day!


Andrew Lynch


From: lcyoung <lcy...@bellsouth.net>
To: n8vem...@googlegroups.com
Sent: Friday, August 9, 2013 9:56 AM
Subject: RE: [N8VEM-S100:1782] IMSAI 8080 CPU card replacement




This may not quite be the right thread, but...

How about some sort of front panel or ability to perform the Imsai/ Altair front panel functionality (ss, set address, run, stop, etc)?

Either on board the CPU or daughter board, or even a semi look-alike front panel? Just a thought. Front panels are cool and useful at times!

Thanks for all your hard work, as well as the great efforts of others.


Leonard KS4RN



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