Looks fine David, two small points: Address inputs to U6 with jumpers JP1 & JP2 should not float if unconnected. Use 1K pull-up on each. Not clear what you have going on with K3 and K4 Also since you have a spare monostable in the LS123, might want to consider separate pulses/display for port inputs and outputs instead of a general single board select. Cute idea using the 123 for board select BTW. John From: n8vem...@googlegroups.com [mailto:n8vem...@googlegroups.com] On Behalf Of David Fry Hi All, I like a number of others on the forum have over the last couple of weeks been starting to learn how to use the KiCad workflow process, I just though it might be interesting to share what I have been doing with the program and get some feedback from other members on the forum. I have been developing another S-100 prototyping board for my own purposes, yes I realise that there are at least 3 others currently available, two of which are dedicated to providing as much prototyping area as possible. This proto board is aimed specifically at I/O port addressed projects and takes a different approach in supplying pre-wired all the necessary S-100 port decode logic and data line buffers/control and presenting all the necessary signals to 3 SIL connectors close to the prototyping area. I am not taking any credit for the design as it is taken directly from the S-100 IDE board I'm just re-cycling the circuitry to make port addressed prototype projects quicker to produce. The board has positions for two voltage regulators, one for the 5v rail, the other can be jumpered for either 12v or 3.3v Regulators have been positioned to allow heatsinks to be fitted as required. Both supply rails and gnd connections run along left hand edge of proto area to facilitate horizontal orientation bussed supply rails Port addressing can be jumpered for 8 or 16 bit I/O port addresses Port address jumpering for a 2, 4, or 8 I/O port window An addition of a Monostable Multivibrator to drive the Board Enable LED Lower 8 bits of address bus buffered for allow further decoding All signals brought to 3 SIL connectors along edge of prototype area My question to all you all is, have I missed anything out with regard to features/signals needed for port I/O based projects ? John, I would be particularly interested in your input I have attached the schematic and a board layout to this post, If there is sufficient interest in the community for this board then I am quite happy (once ironed out) to hand it over to the guys doing pcb production. Regards David Fry -- |