8085 IO ports

Chuck Guzis cclist at sydex.com
Sun Jan 15 12:06:52 CST 2017

On 01/15/2017 09:37 AM, Glen Slick wrote:

> In the EPROM binary dump you posted I see code that is doing IN and
> OUT accesses to the following port locations...

I've seen that technique used to address a device, such as off-chip
EEPROM--basically, rather than employ a separate latch for the address
or map the device into memory space, a block of I/O addresses are used
to directly access the device.   It seems wasteful--and, as the code
points out, rather inflexible, as the 8085 only has the
immediate-operand IN and OUT instructions, but hey, it saves a couple of

So, the first thing that I'd look for is what devices on the board can
be accessed in this fashion.


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