Don and I have hit a road-block on the board with the one-shots for DEPOSIT and EXAMINE (mostly) which is why there hasn't been much activity on it as of late. Don is going to send one of the remaining prototype boards to Crusty for building and testing. I have a board out with Neil Breeden and I think the feedback is similar to ours, although I'm pinging him again on it to be certain.
The original IMSAI FP of course was designed for the 8080 and I've seen some chatter that it might not work properly with the Z80 without special logic because of the different buss status generation. I have a TDL Z80 board in my IMSAI and it works just fine so maybe there is something unique with the N8VEM/S100 Z80 board that's interfering. I don't know. I've subsequently gotten a Jade Z80 board with FP connector so I might give that a try this weekend. I feel that it's close to working and needs a nudge.
From: lcyoung <lcy...@bellsouth.net>
Reply-To: S100-Post <n8vem...@googlegroups.com>
Date: Friday, August 9, 2013 7:31 PM
To: S100-Post <n8vem...@googlegroups.com>
Subject: RE: [N8VEM-S100:1788] IMSAI/Altair Front Panel Mini project
It was just a thought. I have a SMB, and my (your) monitor works with the dual Serial IO, as well as the Console board. Must put a box together some day, however. Having not much luck finding card guides. I'd make 'em but for the arthritis! It was kind of cool having a front panel, though.
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.
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!
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.
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