The Sinclair QL Forum

What equivalent PNP bi-polar high-speed switching transistor is suitable instead of a ZTX-510? I'm a noob looking at datasheets and none of the PNP transistors I can find are quite the same. ZTX-510 seems to be a tricky one to find. It is not necessary to use a bipolar transistor. If I had to desig...

does the mini backplane flip the top board that comes out from the QL - I know it flips the board that would be entirely within the case? Maybe Dave or Derek can answer this. From the routing issues involved, I think it's likely that the outer board is not flipped by the mini backplane. Which makes...

It is available in a PLCC package which makes it easier to accommodate on a smaller board - it was used in the Atari ST machines so there is a fair bit of old stock around. That sounds better than DIL and would allow a solution without PLD - probably an advantage for tinkerers. The driver changes t...

The MC68901 sounds like a nice idea, since a good UART is also needed for the QL. But how about the large 48 pin DIL case and the fact that it is obsolete?

Same with QPC, that hasn't ever stopped you from bashing its closed-sourceness. No, I didn't even mention QPC and don't care if it is closed or not. I appologize, must have been a different Peter who always post things like As a free emulator my recommendation would be SMSQmulator. Unlike QPC and Q...

Many thanks Martin! Apparently I underestimated how useful the Q68 high resolution timer is... It's surely possible to do without the 2 ms for initialization and autonegotiation, so the accuracy of PING looks like the only severe issue when a 20 ms / 50 Hz timer is used. But removing the Q68 timer d...

Derek_Stewart wrote:I meant the Qubide Ram IDE Card by José Leandro, which connects to a standard QL.

Do you mean this one? http://hardware.speccy.org/temp/qubide-i.html

Pr0f wrote:I don't know how latent the external interrupt line is (as that would have to be used if not polling for interrupt statuses on the default interrupt scheduler.

This latency is not predictable as other interrupt handlers use the same level.

Same with QPC, that hasn't ever stopped you from bashing its closed-sourceness. No, I didn't even mention QPC and don't care if it is closed or not. Apart from that, small scale hardware production of comprehensive circuits is a completely different issue than distributing software. And even for HD...

I also use the QL's hardware RTC clock (PC_CLOCK is it?) in places. Yes, this is identical to the QL. From a very quick digest of the datasheet for the CP2200, the places where a timer may be required: [...] Waiting for Flash Write - the write itself is done by hardware and no timers are required t...