Pico Garry 2350 Part 4: Memory Read Select
Following on from the previous part in this series I now turn to /ROMEN and /RAMRD signals, collectively called Memory Read Select. When the CPU wants to read from memory the gate array has to decide whether that read should come from RAM or ROM. This decision is based on the memory bank being accessed …. Read More
Pico Garry 2350 Part 3: CSIGS (Conditional Signals)
This is the third part of my ‘live blogging’ series as I create a replacement gate array for the Amstrad CPC using a Raspberry Pi RP2350B microcontroller. In this part I work on the /CAS, /244EN and /MWE signals. /244EN and /MWE are only asserted during a fixed portion of the gate array cycle and …. Read More
Pico Garry 2350 Part 2: FSIGS (Fixed signals)
This is the second of my development logs as I work to create a replacement for the Amstrad CPC gate array based around a Raspberry Pi RP2350 microcontroller. In the previous article I divided the gate arrays input and output signals into a number of blocks depending on their function. In this article I implement …. Read More
Pico Garry 2350 Part 1 – Signals
In 2020 I began a project to emulate the gate array from an Amstrad CPC computer using a Raspberry Pi RP2040 IC (as used in the first generation RPi Pico microcontroller boards). The project ran into challenges due to insufficient GPIO pins on the chips and the need to convert voltage levels for signals between …. Read More