The PC7486SLC-based Mega PC upgrade really is running at 33 MHz. Great news: the math coprocessor for the 486SLC has arrived and is recognised perfectly. It is a ULSI Advanced Math Coprocessor SX/SLC rated at 33 MHz, part US83S87. The diagnostic software also identifies it as a ULSI 84x87. I’ve... Continue reading

The replacement PC7486SLC motherboard is in. It passes POST and, unlike the original 386 board, recognises the hard drives perfectly. That strongly points to a fault somewhere in the original motherboard’s storage subsystem or related circuitry rather than the drives themselves. The old board will still make a useful spare.... Continue reading

To reproduce the fault, I ran the Saturn for more than an hour until it was thoroughly warmed up. The music player was more than sufficient for this. I then made some recordings to help narrow down where the noise seemed to be coming from. This meant investigating the Saturn’s... Continue reading

Picked this up on eBay from the UK and gave it a bit of a clean. It has become my favourite Mega Drive controller. Internally it is much the same as another Mega Drive controller I cleaned yesterday, although that one sadly had some tabs snapped off the D-pad. Amstrad’s... Continue reading

A quick look inside the Amstrad Mega PC with the system pulled apart. The Sega Mega Drive hardware sits on a dedicated ISA card inside the PC. This is the same machine that arrived in not-so-good condition with NiCad battery corrosion on the motherboard. Related posts Amstrad Sega Mega PC... Continue reading