On 2019-Mar-12, at 1:21 AM, shadoooo via cctech wrote: Comparing an RC25 cartridge in my hands with pics of a 9457 cartridge online; at a quick glance they look similar, with the two angled corners and grip area. However they actually have significant differences: - the RC25 has a sliding door over the hub mount, while the 9457 doesn't, - the head-arm access door is very different between the two, - the hub attachment appears to be different. So it doesn't look like the cartridges would be swappable in either direction. Whether there might be compatibility at the platter/encoding level I have no idea. The concept, platter size, and time period are similar enough that one would wonder whether they shared some development history, such as (speculating) initial dev by CDC and licensed and repackaged by DEC.