== Technical ==
=== AMSSIO (v1,v2,v3) ===
Connects between Z80 CPU and mainboard. I/O Ports for AMSSIO v1,v2,v3 are:
Observe that the baudrate CLK sources differ for v1,v2,v3. In v3 the CLK is fixed, v1/v2 have different jumper-selectable CLKs. And, the photo shows a different CLK crystal than the schematic. So, don't expect different AMSSIOs to be compatible with each other.
=== AMSSIO----II (v4) ===
'''AMSSIO-II is a newer version, using a 44pin 16C850CJ instead of the 24pin MC6850. Aside from the schematic (v4see below), there is no documentation or source code for AMSSIO-II. I/O base address can be FBE0h or FBF0h (jumper-selectable). Unlike the previous versions, this version also connects to the Z80'''s interrupt input.
AMSSIO-II The "PC" attached to the "16C850CJ" part number (labeled as "16C850CJPC" in schematic) is a newer version, using a 16C850 instead of meant to say that the MC6850chip is wired to "PC Mode" (SEL, Pin 34 = GND). Aside from In the schematic PC Mode, the chip tries to decode PC ISA bus addresses (see belowCOM1-4 = 3F8h,2F8h,3E8h,2E8h), there is no documentation or source code for AMSSIO-II. I/O base some address can be lines are swapped, so the AMSSIO maps to FBE0h or FBF0h (selected by S1 input) whilst the chip "thinks" it is mapped to COM3/COM4 ISA bus addresses (3E8h/2E8h). ''Unclear: the jumperon S1 should change "A8" -selectablebut the schematic is wired as if "A4" changes - which would require a jumper on S2, not on S1 (?).'' * [[Media:XR16C850.pdf ]] - 16C850 Datasheet
== Software ==
== Weblinks ==
[http://www.citystromerzacho.dkorg/CPC/ AMSSIO project <s>lives</s> sleeps here!]
[[Category:Hardware]] [[Category:Peripherals]] [[Category:Serial interfaces]] [[Category:DIY]]