The Sinclair QL Forum

OMG, I've just realised the EPROM in the photo from QLWorld is in upside down

Here is a binary image of the NEC D8749HC Thanks. I do not think there is a 8049 binary file Just did some digging through my QL filing system and I can't find where I got the 8049 binary from myself (it's so long ago, nothing found on Dilwyn or Thierry Godefroy's sites - no binary, just the listin...

Some good notes there - SCL is never read - as this is the I2C clock - and as the Minerva implements it as a single Master role - the QL always drives the clock - the SDA signal on the other hand needs to be read and written. Never having had Mk2 Minerva hardware I wasn't sure whether SCL read had ...

That's intriguing, it's dated 1987 so may have been programmed by user (8749HC windowless One Time Program chip). But why not just use 8049 that came with QL?, perhaps modified for some reason (my Schon IPC variation was 8049). Be interesting if you can get binary dump and see if it differs from kno...

Could a fixed capacitor not be used? Not if you want long term accuracy, it took a while until I got mine just right (it's in PCF8583 datasheet). Though saying that the RTC chip on the SGC/GC does without one. A useful mod to original MK2 might be to provide link to allow 48K or 64K EPROM. Maybe a ...

Hi, As I mentioned earlier, I was redrawing the Minerva MkII PCB, from the original PCB I have, with a view to producing some more PCBs, do you think this is a good idea? If you do build some beware of the green trimmer capacitors, I bought 50 from China and only half worked. The fault is the way t...

Just to set the record straight that’s not me :D Dave and I did laugh at the irony of two English guys with an interest in a little regarded Sinclair machine (present company excepted) washing up within a couple of miles of each other in a Texas suburb…Minerva truly has mystical powers… Ah, would t...

so looking at those stripped circuit boards - the chip under the ROM was a 13 Input NAND gage - so presumably used to do the finer address decoding for the SDA / SCL Using a 7430 (8 input NAND) would have been enough, SGC allows direct access through to $BF80-BFFF. Here's something I wrote a few ye...

That's interesting, thanks for posting it, never seen a MK2 up close but I have always suspected there is a 7430 lurking under the EPROM. It's the only way I could figure it out (ie. providing DECODE in EQN file). I did a discrete version, replacing GAL function with 7451/7400/7474/74126 (which I su...