| ECB Prototyping Board with I/O decode - ordering new boards [message #89] |
Thu, 26 November 2015 02:40  |
ewout
Messages: 30
Registered: October 2015
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EDIT:
John has designed a new v3 Prototype board.
https://www.retrobrewcomputers.org/forum/index.php?t=msg& ;amp ;th=132&start=0&
{I want to start a new batch run of the 'ECB Prototyping Board with I/O decode' as nobody is listed anymore for that board. If anyone is also interested please let me know in this thread.
Maybe if someone has a preference for the 'ECB C'T Protoboard' please also let me know here. Personally I find the header exposure of the ECB bus lines on the Proto w/IO board a big advantage if I want to do some on board testing with logic analyzers.
Planning to order the boards at Eurocircuits as I have a student discount for small prototype batches though my university. The board will be send from Europe.
According to the board calculator, a eurocard format board (100mm x 160mm) with 2 layers cost €10.08 with an 30 boards batch, with 40 €8.26 and 50 €7.44. Excluding the postage costs of course  . 50 boards brings it on a total of €372~ which I want to consider if enough people get in on it.
The final costs will probably be the same as they take a very complex design as an example.
Current total: 18+ boards
5 myself
5+ Sarah
2 Andrew B
2 computronik
2 crusader49
2 inerlogic
Inventory left: 22}
[Updated on: Sun, 19 February 2017 02:38] Report message to a moderator |
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| Re: ECB Prototyping Board with I/O decode - ordering new boards [message #561 is a reply to message #559] |
Sun, 24 April 2016 09:51  |
jcoffman
Messages: 332
Registered: October 2015
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Caution: if the prototyping board has not been re-ordered, then there is a circuit update needed.
Currently the board will select on IORQ# at a range of 16 selected device codes. For the Z80, this is incorrect. I/O requests are identified not by IORQ# low, but by the combination IORQ# low and M1# high. In an interrupt environment, the Z80 Interrupt Acknowledge operation is identified by IORQ# low and M1# low. Hence, if only IORQ# low is identified, spurious I/O selects can occur on an Interrupt Acknowledge request.
AFAIK, all RetroBrew I/O boards get this I/O qualification correct. The prototyping board should get it right, too.
Since the Z80/Z180 SBC's do not operate in an interrupt environment, this is not an issue. It could be an issue with CPU boards which do operate with interrupts enabled: SBC-188, Mini-M68k, and KISS-68030.
If the board has been re-ordered already, I wouldn't sweat the issue. I've use the old board for successful prototyping on two occasions. The circuit modification can be done as part of the prototype. Just be aware of the oversight.
--John
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