Re: [Simh] [simh] Scrambled text in VAXStation 3100m38 GPX graphics screen
On 22/06/2019 20:21, paulhar...@btinternet.com wrote: > My suspicion is that it is memory trampling in the font caching > implementation in the emulated VCB02 device in SimH. The VCB02 device > uses the same memory planes for font caches as for screen bitmaps - > the manual says: > 1.6.1.1 Font Storage and Access Fonts are stored in an undisplayed portion of > the bitmap. Ordinarily, a font is stored only in one plane and is transmitted > from that plane to itself and > others when a character is written. Fonts are normally stored in the > off-screen portion of the VCB02 bitmap. > > Calling Matt Burke - can you spot anything odd in your implementation of this > aspect of the VCB02? > When I released the VCB02 I mentioned that there were known problems with VWS and UWS. Although DECwindows appeared OK with my testing it's not surprising that it's also affected. I hope to fix this eventually but it might not happen for a while as experience tells me it will take many hours to track this one down. Basically you have to enable debugging so that every drawing operating is logged then wait for the screen to get corrupted. You then need to count the exact pixel offset and size of the corrupted area. Next the debug log file (which is likely several gigabytes by this point) is searched to try and find the exact drawing operation that caused the corruption. Then the manual needs to be consulted to find out what subtle functionality was missed from the implementation. A change is made, which usually breaks something else and the cycle continues :) Matt ___ Simh mailing list Simh@trailing-edge.com http://mailman.trailing-edge.com/mailman/listinfo/simh
Re: [Simh] [simh] Scrambled text in VAXStation 3100m38 GPX graphics screen
On 06/21/2019 11:40 AM, simh-requ...@trailing-edge.com On Behalf Of Jon Elson wrote: > The first picture looks like it is doing some kind of transliteration into > Cyrillic, is it possible the font selection got switched? > Jon Not that simple. The fonts get corrupted one by one, and character substitutions aren't just Cyrillic - they are numbers and punctuation also. I can provoke it fairly easily by starting three or four standard VMS applications - e.g. Paint, Fileview, and Calendar, maximising them to full-screen and using right click to lower them to see the underlying windows. My suspicion is that it is memory trampling in the font caching implementation in the emulated VCB02 device in SimH. The VCB02 device uses the same memory planes for font caches as for screen bitmaps - the manual says: 1.6.1.1 Font Storage and Access Fonts are stored in an undisplayed portion of the bitmap. Ordinarily, a font is stored only in one plane and is transmitted from that plane to itself and others when a character is written. Fonts are normally stored in the off-screen portion of the VCB02 bitmap. Calling Matt Burke - can you spot anything odd in your implementation of this aspect of the VCB02? -- Paul Hardy web: www.paulhardy.net ___ Simh mailing list Simh@trailing-edge.com http://mailman.trailing-edge.com/mailman/listinfo/simh
