Posted By
SVS
on 2016-03-08
15:12:16
 |  Light pen and TED
Another quiz for you, old geeks 
Do you confirm the correct working of bit 2 of TED register 09, as IRQ flag from Light Pen trigger?
If yes, is it correct to say that it is not implemented into the C16 hardware?
(info for next Ultimate map, of course  )
Thank you
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Posted By
JamesC
on 2016-03-08
20:22:14
| Re: Light pen and TED
We have software that is intended for a lightpen, and I don't recall any complaints about it not working.
What document gives the idea that a lightpen does not trigger an interrupt?
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Posted By
SVS
on 2016-03-09
05:07:38
| Re: Light pen and TED
@JamesC I agree with your comment. I found the info (not implemented) in some old documents I browsed years ago for UltimateMap compiling.
Now I'm updating it with a doc by ANCO, where it is specified that C16 cannot use that dedicated IRQ bits (both the IRQ flag and IRQ enabler).
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Posted By
Chicken
on 2016-03-09
05:18:55
 | Re: Light pen and TED
All documents I've seen state that the lightpen interrupt is not implemented. I'm not sure why that bit was called "lightpen" then anyway. Maybe because it's the same bit as on C64 (I haven't checked that)?
There are at least two lightpen reviews in Compute mit (most likely in the C16 special issues). One is on the TROJAN lightpen, the other one on the OPTELPEN. At least the former mentioned some technical issues a lightpen has to face on a C16. I'm pretty sure it's about the missing interrupt.
SVS: You could check the software coming with the TROJAN lightpen to make sure it does not use that bit.
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Posted By
gerliczer
on 2016-03-09
05:22:21
| Re: Light pen and TED
Nobody has to check any kind of program. There is no light-pen (or any other external IRQ) input on the TED. There is nothing to trigger that interrupt.
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Posted By
Chicken
on 2016-03-09
06:08:59
| Re: Light pen and TED
gerliczer: My comment was meant like "… to see how it's done". Obviously, it wasn't that obvious Especially with nothing to trigger an interrupt, it might be interesting to see how this problem is tackled. Afterall, there are at least two different types of lightpens around for this platform.
SVS:
I checked the afore mentioned magazine. It's special issue 1/88:
http://plus4world.powweb.com/publications/Compute_Mit_SA_1_88
On pages 9/10 you'll find the TROJAN review. It mentions the missing hardware implementation. The sarcastic comments on the program's qualities made me laugh again – just like they did decades ago 
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Posted By
gerliczer
on 2016-03-09
10:37:43
| Re: Light pen and TED
You're right, Chicken. However, this topic is about the TED Interrupt Mask and Status registers. Once SVS will get to the point where he wants to include the TROJAN and/or OPTELPEN interface into the Ultimate Map we can get back to them.
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Posted By
SVS
on 2016-03-09
13:02:22
| Re: Light pen and TED
It seems that the light-pen had to be plugged to the Joy1 connector. Then it is supposed the movements are detected by keyboard routine (!)
@Chicken:
>> The sarcastic comments on the program's qualities made me laugh again – just like they did decades ago
Please share it with us, non-German speakers
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Posted By
Lavina
on 2016-03-10
14:50:36
 | Re: Light pen and TED
I have a working lightpen for the plus4. It is on the gotu website with matching software and the blueprint.
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Posted By
Chicken
on 2016-03-11
13:33:49
| Re: Light pen and TED
SVS:
The TROJAN and OPTELPEN lightpens have to be connected to the joyport, that's right. Since the OPTELPEN works with the TROJAN software, both lightpens can be considered "compatible". However, the OPTELPEN got a much better review. Though, the lacking software support was pointed out.
Anyway, "drawing" with the TROJAN software is not like doodling with a pen on screen. The procedure described in the review makes it sound anything but easy.
It's not really clear (to me) how the vertical check works (the review mentions raster interrupts but it's rather vague). The horizontal check involves some routine in char mode that creates horizontally moving black bars on screen. When these reach the lightpen's position (with the TROJAN lightpen it's not working all the time), the horizonal position is set. It's like a pressed fire button (or a pressed key).
I'd really like to see Lavina's lightpen in action, e. g. drawing something on screen.
About the TROJAN review …
The funny part is when the author describes how he's barely able to draw a stick figure with the software and then wonders how they dared to call it "CADMASTER"
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