Search found 1158 matches

by tofro
Thu Nov 23, 2017 2:01 pm
Forum: Software & Programming
Topic: Interrupts and their handlers on the various QLs
Replies: 5
Views: 148

Re: Interrupts and their handlers on the various QLs

The QL is not really an interrupt-driven computer, at least not in a classical sense. The most significant (and, in a standard QL - basically only, at least if you look into the ones relevant for games) interrupt source is a 50/60Hz interrupt that is handled by the system as a trigger to frequently ...
by tofro
Thu Nov 23, 2017 11:22 am
Forum: Software & Programming
Topic: Q68 Powered Arcade Game
Replies: 22
Views: 581

Re: Q68 Powered Arcade Game

I think SLUG works by putting delays in keyboard read systems IIRC, whereas Slowgold is written to use interrupts or scheduler lists IIRC (haven't got the sources to hand to check), so it's quite possible that both might be of use in situations where some software needs to be slowed down. No way on...
by tofro
Mon Nov 20, 2017 5:29 pm
Forum: QL Emulation
Topic: Q-emuLator and macOS High Sierra
Replies: 5
Views: 325

Re: Q-emuLator and macOS High Sierra

Try typing anything with either caps lock on or the shift key held down - the letters appear correctly, but space, return, delete, the arrow keys - none of these respond. A general bug or just my setup? Keyboard membrane of your emulated QL is probably broken - They tend to do that with age. Order ...
by tofro
Sat Nov 18, 2017 5:40 pm
Forum: General QL Chat
Topic: Sinclair QL printer (Seikosha) cable
Replies: 8
Views: 418

Re: Sinclair QL printer (Seikosha) cable

Simon, on the DB-25 end, 1 is "Shield" (which is normally GND) and 7 is "signal ground" (which is normally GND as well). For non-exotic applications like QL-to-printer, that is the same. So, feed 7 of the 9-pin to both 1 and 7 on the DB-25. On second thought, shielding (the mesh ...
by tofro
Fri Nov 17, 2017 12:45 pm
Forum: Hardware
Topic: Q68 Notice 3 - Update
Replies: 44
Views: 2099

Re: Q68 Notice 3 - Update

Speed reduction: Note that, even if the contention created by video circuitry eats a lot of memory bandwidth, the 256 and 64k colour modes are way easier (and faster) to handle than the original QL modes: Setting a pixel in mode 4 or 8 means ⋅ pick the word containing the pixel from video ...
by tofro
Tue Nov 14, 2017 3:17 pm
Forum: Hardware
Topic: Engineering mules....
Replies: 16
Views: 669

Re: Engineering mules....

I remember that article from QL User, but can't remember whether it actually worked. It apparently doesn't attempt to reset the 8049. Jan. Jan, as far as I remember, this shouldn't be necessary - The 8049 resets itself already when seeing <CTRL><ALT>7 after sleeping for a while. Before that, it iss...
by tofro
Tue Nov 14, 2017 12:09 pm
Forum: Hardware
Topic: Engineering mules....
Replies: 16
Views: 669

Re: Engineering mules....

The simplest you can do is have QMON loaded in your QL - That redirects the level 7 interrupt into the debugger.

Tobias
by tofro
Mon Nov 13, 2017 7:27 am
Forum: Hardware
Topic: Engineering mules....
Replies: 16
Views: 669

Re: Engineering mules....

My guess is the debugging device was software only (Some specific ROMs). I have, however, never heard of any of such versions that would have survived. So I'd guess another time and assume these ROMs were made on the go when looking for a specific problem and later discarded.

Tobias
by tofro
Sun Nov 12, 2017 10:33 am
Forum: Hardware
Topic: Microdrive Unit Design
Replies: 95
Views: 6012

Re: Microdrive Unit Design

Technical docs and hardware shows there are 2 heads, so your calculations need to reflect that 2 heads are in use. Erm, no. Probably not. There is no mechanism that ever uses the two tracks on the tape in a parallel way . The tracks are being used for alternate bits , most probably to compensate fo...
by tofro
Thu Nov 09, 2017 12:17 pm
Forum: Hardware
Topic: PSU alternative?
Replies: 55
Views: 8162

Re: PSU alternative?

Setting the ground reference of the +/- 12 V lines to the +9V line looks weird, at first, but you need to look into the PSU in order to understand it. Sinclair has simply saved on one strand of wire, the 14VAC ground. Most probably, the complete transformer is one continuous winding, the input to th...

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