The Sinclair QL Forum

The 16550 was an 'improvement' which actually had a set of it's own problems but the main star of the show was a 16-byte receive and transmit FIFO. That's mildly put. If I remember correctly, the 16550 was so buggy that the FIFO could not be used at all. National Semiconductor later released the 16...

Before I move on to the 8302 ULA, a new build based on the old components should definitely also incorporate the following: IS it worth it, though ? This means heaps of work to reimplement somewhat less broken form of half-assed solutions, just so that the user can choose to change ULA2 or IPC sepa...

@all In general I think Hermes is a must. It is a great pity someone like Lau Reeves or indeed Lau himself did not program the IPC as the number of fixes and options it would have opened for other hardware (see my next post) is everything but trivial. Is this really so dire ? methinks there are mor...

Hermes deserves a much closer look because it has a couple of features which make it potentially more usable when it is not plugged into a regular IPC socket on the QL motherboard, in addition to all the corrections to the original IPC functionality. The most interesting are probably the pins it doe...

@Janbredenbeek The 16450 was the principle UART used in the PC and it has a... sort of 1.5 byte receive buffer, actually one byte for the received byte while the next byte is still in the reception process. It's little more than a serial to parallel and parallel to serial converter, ALL the handshak...

The I/O subsystem: 8302 ULA and IPC These two actually work together from the standpoint of the user to provide all the various types of I/O on a bare QL. The interplay is especially obvious in the case of serial ports, where the 8302 ULA handles serial port transmit, and the IPC handles serial port...

68008FN (if only it was available sooner...) Let's shortly review a version of the 68008 that came out about a year after the original 68008, in a smaller 52 pin PLCC package, which is also cheaper to make. The small down side is relatively rarely used 52-pin (rather than 44 or 68 pin) PLCC socket,...

This requires remembering things from a good 25 years ago if not more... If I remember right, it's not about rotating the head because that's obviously a no go. There would be two possible approaches: 1) Use the two channel erase heads on each side of the actual RW head in order to do some encoding ...

... DO different driving strategy, different modulations ( I like my dual signal, QAM-like scheme) etc. Before that, I have to try it on microdrive. So I dug one out of my shelves. But motor was loud, so I opened it to lubricate it, at least enough to get trough tests. ... I took a look at writing ...

So how does one go about building QL compatible hardware? Well... the first consideration is should one use the original chipset or not, the original chipset being the two ULA chips and the IPC. So, let's first explore the option of using the original chipset, either building hardware from scratch o...