tag:blogger.com,1999:blog-12349577.post4067079122633240898..comments2023-11-02T09:19:52.430-04:00Comments on Purple Avenger: Remembering the pioneers of spacePurple Avengerhttp://www.blogger.com/profile/11994076252416384045noreply@blogger.comBlogger3125tag:blogger.com,1999:blog-12349577.post-35824027953912988412007-01-30T23:32:00.000-04:002007-01-30T23:32:00.000-04:00in fact, I was told once that it was the EXACT pro...<i>in fact, I was told once that it was the EXACT processor used in a commodore 64, or was it vic 20? Something like that.</i><br /><br />That's not true. <br /><br />The SP0's (cockpit display/keypads) and AP101's (the 5 main flight computers everyone's heard about) are not even microprocessors. <br /><br />They're a backplane based system with a slew of boards that plug into the backplane's. The SP0/DEU "CPU" consisted of somewhere around (if I remember correctly) 19 boards, each built with discrete transistor logic - i.e. not an IC anywhere on them. <br /><br />We're talking seriously "old school" here. We're also talking seriously radiation hard too. The discrete logic and magnetic core made the things virtually impervious to any sort of radiation, and the magnetic core is by nature non-volatile.<br /><br />one of they guys had to write a memory scrubber for whatever the first military mission was to wipe the core boards clean. You can't just erase it, there are hysteresis effects that remain after a simple erasure. You gotta hit it with many patterns over and over to really get it clean.Purple Avengerhttps://www.blogger.com/profile/11994076252416384045noreply@blogger.comtag:blogger.com,1999:blog-12349577.post-52199134356573996442007-01-30T15:08:00.000-04:002007-01-30T15:08:00.000-04:00Yea, aerospace/defense systems are a whole differe...Yea, aerospace/defense systems are a whole different world than commercial stuff.<br /><br />The lab toys are certainly a lot more exotic and expensive.<br /><br />The Shuttle cockpit display video hardware was incredibly advanced architecturally for stuff built in the early 70'. <br /><br />The CPU that drove that hardware was incredibly primitive though - a single accumulator architecture with no protection mechanism at all. When the program went nuts, there were not GP faults, invalid instruction, exceptions, etc - it just kept executing and wasting the core (these machines used actual magnetic core memory).<br /><br />The video hardware had a notion of sprites, display lists, and object on the list could have properties like direction and speed, rotation, and intensity variability.<br /><br />So you could take some symbology element, slap it onto the display list and the video processor itself would slide it across the screen, rotate it, and vary its intensity without the wimpy SP0 integer CPU having to do anything. <br /><br />That allowed a very wimp and slow CPU to do very impressive display manipulations and not get saturated.. We didn't see those sorts of architectural features in a PC video card until well into the SVGA era.<br /><br />In a way it reminds me a little of the old IBM PGA video adapter that had a ton of hardware assist and an onboard 8088 video processor. You didn't manipulate the high-res screen on a PGA directly, you sent it directions through a small buffer, and its onboard 8088 handled an internal display list.<br /><br />Cost killed PGA (~$2,000 back in 83' or 84', and another $2,000 for the monitor) and the EGA took hold instead. If the PGA had taken hold as a video standard, PC video systems would have advanced a LOT more quickly.Purple Avengerhttps://www.blogger.com/profile/11994076252416384045noreply@blogger.comtag:blogger.com,1999:blog-12349577.post-39846852020900387542007-01-30T10:59:00.000-04:002007-01-30T10:59:00.000-04:00Sounds like fun. More fun than working on web serv...Sounds like fun. More fun than working on web services...Mikehttps://www.blogger.com/profile/15138360416884607340noreply@blogger.com