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RE: [N8VEM-S100:2306] Next board?

Joe, Andrew and I have been working on a V2 System Monitor Board for some time.  Already have done one prototype but another is needed and is in the works.  FYI I am attaching a schematic.

The issue is mainly how much can you get on one board.


The current V2 has the following:-


Display 24 address lines with either a HEX display or Bar LED’s (cheaper)

Display 8 or 16 bit data lines coming into the current bus master in halt/single step mode

Set a hardware (24 switches) breakpoint anywhere in the current masters 24 bit address space so once the CPU accesses that location it halts and can be single stepped from there.

A Single step function.

Lower any combination of the 4 TMA(DMA) S100 lines so that in theory, up to 16 CPU’s could control the bus.

555 Timer generated (long) signals for reset and slave clear.

All address lines are now  latched so fast CPU’s like an 80386 can display valid data on the HEX display.

LED (stretched) light flashes and status signals for the major S100 bus status/control signals, (pWR*, SOUT, MWRT etc.).  These remain valid during single step mode.

A few other tweaks.


The only major IMSAI function not included is “deposit” and “deposit next”.  These were too difficult to add in a generalized manner independent of CPU speed (i.e. no single shots)  and can easily and better done via the current master/CPU monitor.


We are just doing a second prototype version and hope to have it in a few weeks.  I don’t anticipate any further issues but did not want to go for a final “production” run because there were numerous small changes on the previous prototype.   Should have it running in say a month. Stay tuned and keep an eye on this forum.






From: n8vem...@googlegroups.com [mailto:n8vem...@googlegroups.com] On Behalf Of Joe Herdler
Sent: Wednesday, February 5, 2014 8:32 AM
To: n8vem...@googlegroups.com
Subject: [N8VEM-S100:2306] Next board?


Hi Andrew and everyone else,


I was just wondering what the next board to be made available for pre-order will be. I received my Z-80 V2 board early last week, and now I am starting to populate it with components.  I am really getting into this project as well as Sergey's Xi 88 machine.


One thing that I am really curious about, and that is a front panel display. I think that it would be really cool to have the IMSAI type array of switches and lights.


As far as Pay-Pal issues, I would be willing to wire transfer money for boards via Western Union or Money Gram.





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Attachment: Printing S100_SMB V2-Rerun 3-sch.pdf
Description: Adobe PDF document