On 03/07/2018 06:36 PM, Mia Magnusson wrote: > > Another thing in the timeline is when 64kbit DRAMs were reasonable to > use in a home computer. The older 16kbit DRAMs did require three > different voltages and for a VIC-20 class computer that might have had > a noticeable impact on production cost (although the VIC-II and SID > ended up requiring 12V DC making it necessary to have two voltages in a > C64, so using 16k DRAMs would "only" had required one more voltage but > atleast a bunch of capacitors to generate a negative voltage from the > 9V AC line). (Btw Atari 600XL did use 16k*4 bit DRAMs which also only > required a single 5V DC rail, so the introduction of Atari 600XL is > also an important step in the time line). Take a look at the shematics for the ZX spectrum. It uses 4116 in one bank and the circuit to produce the +12V and -5V is pretty simple. > Btw judging by what happened with the TED/264 line it's obvious that > Commodore didn't really know what they were doing at some point in > time :) Well, it was supposed to become a spectrum killer for less than $100. The original design was even more simple than what became the C116. The prototype board can be seen here: http://plus4world.powweb.com/hardware/Prototype_PI9 And here's the prototype in a C116 enclosure. Notice the lack of the PLA banking logic and 6529. http://plus4world.powweb.com/hardware/Commodore_116_NTSC_Prototype The problems started when they began to add stuff to the design. Gerrit Message was sent through the cbm-hackers mailing listReceived on 2018-03-07 19:00:57
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