It started showing an error on the front panel, which is supposedly a SIMM error. Removed all SIMMs and it was OK, but showed only 2MB memory. I installed the original SIMM that was in and it said 3MB again, so I assume the onboard memory is 2MB and the SIMM adds an extra 1MB. When I install any of my SIMMs now (either in pairs or just one) I get the error lights, so they must be incompatible.
Does anyone know what type of memory I require? Does it need to be supplied by HP, or is it just a particular type of SIMM?