Characterising Am9511A-1 APU

I’ve built a Z180 based board, supporting the AM9511A APU. Partly for historical enjoyment. Partly because the AM9511A-1 is actually still faster at arithmetic than “modern” Z80 devices. For example, from the Am9511/Am9512 Floating Point Processor Manual by Steven Cheng, we have comparison tables. On average the Am9511A APU (at 1.966MHz) produces a hardware floating […]

8085 Software

This covers creation of software support for the 8085 CPU within the framework of the z88dk and also with MS Basic 4.7. Specifically, the 8085 undocumented instructions will be covered, and some usage possibilities provided. Future work is to build a re-entrant IEEE floating point library specifically using the stack relative instructions found in the […]

Three Rings for the Z80

Over the past few years I’ve implemented a number of interfaces for Z80 peripherals based on the principal of the interrupt driven ring buffer. Each implementation of a ring exhibits its own peculiarities, based on the specific hardware. But essentially I have but one ring to bring them all and in the darkness bind them. […]

Yet Another Z180 (YAZ180 v2)

Testing on the YAZ180 v1 , shown below, is now complete. I don’t want to use it for further driver and platform development, because the PLCC socket for the 256kB Flash is becoming worn-out. It will continue to operate as an augmented Nascom Basic machine, with an integrated Intel HEX loader (HexLoadr) supporting direct loaded assembler or […]

Yet Another Z180 Project (YAZ180)

I’m thinking about a new project, something a little unusual but still with a rich history of information upon which to base the build. On Tindie, I found the RC2014 project which is a build of a Z80 platform but based on some modern components. That got me thinking. My next project must be a Z80 […]