I'm trying to build a Arduino based project to read/write to MOS6550 RAM (1024 x 4 bit)
Datasheet is here:
https://www.zimmers.net/anonftp/pub/cbm ... asheet.pdfLooking at the datasheet there is sparse information on exactly what timing are needed and the logic. Read/Write waveforms would have been nice.
Quote:
6550 cycle operation is controlled by the PHI2 clock. Addresses are presented to the address pin then PHI2 is low and are latched on chip to the rising edge of the PHI2 clock
The 6550 outputs are in a high impedance state whenever the memory is de-deselected, PHI2 clock is LOW, or R/W is LOW
I am trying to interpret this and don't think I have the logic right.
Writing:
PHI2 LOW, RW LOW, Chip Selected
Set Address pins
Set Data pins
PHI2 HIGH
Reading:
PHI2 LOW, RW HIGH, Chip Selected
Set Address pins
Set Data pins
PHI2 HIGH
Does this look correct? Is there a better datasheet available containing timing diagrams?