Ideas for a simple, but somewhat extendable computer bus

Jim Brain brain at
Sun Nov 19 00:48:43 CST 2017

On 11/18/2017 1:46 AM, emanuel stiebler wrote:
> On 2017-11-17 18:11, Jim Brain via cctalk wrote:
>> I'm currently working on a single board computer system, designing 
>> from scratch partially as an education experience, and also as 
>> something that might be of interest to others.
>> I've laid out the first version of the SBC, and I realize it would 
>> cost nothing to add an edge connector on the PCB, allowing expansion 
>> options.  As well, assuming the design has any merit, I can see 
>> creating one of these SBcs for each family (8080/Z80, 65XX, 68XX, and 
>> maybe even 16 bit options like TMS9900, 68K, etc.)
> You know this projects?

Looking at the schematic for the ECB, I cannot find any description of 
the signals BAI, BAO, IEI, and IEO.  Can anyone shed some light on the 
function of these signals?


Jim Brain
brain at

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