Today after class we were left with an exercise of creating schematics and combining two components we learned about today. The exercise is to combine two 1kx3 NOR MOS PROM components into a 2kx6 PROM component with floating gate transistor programming. (1k ones also use this).

I wanted to check if my understanding is correct so i'm posting this to get replies on whether something doesn't look right or if something is missing. I am just suppose to draw a memory cell of these ROMs and not the entire logic behind it so sense amps and other write/read buffers are omitted.


I have drawn a decoder which decodes 10 adress lines into 1024 word lines and i have 3 bitlines connected to a pull-up network consisted of p-mos transistors. The interconnections in the memory cell are programmed by floating gate transistors. I have drawn with 3 lines in the base to indicate that.

And finally i connected the two schematics into one 2kx6 PROM component: 2kx6 PROM

Is this how NOR type is supposed to be connected? I'm sort of mixing the NOR and NAND types and am not sure if this is correct. If this is correct how would i make a NAND type since all that's different probably is the configuration of the interconnection transistors.

  • 1
    \$\begingroup\$ No, it is wrong. First think of how many 1kx3 you need to make a 2kx6. (Count the bits) Then split the problem in a data width and a data depth issue. But you are getting close. \$\endgroup\$ – Oldfart Jan 11 '19 at 20:39
  • \$\begingroup\$ @Oldfart How about the original 1kx3 component? Is that ok? \$\endgroup\$ – EdwardBlackdd Jan 11 '19 at 20:46
  • \$\begingroup\$ I am not sure enough. That course was 35 years ago, so I am not going to burn my fingers on that. I prefer to pretend ignorance rather then be wrong. \$\endgroup\$ – Oldfart Jan 11 '19 at 21:12
  • \$\begingroup\$ I don't think that it is relevant that the PROM is a NOR device. You really need to ask your instructor about this. \$\endgroup\$ – Elliot Alderson Jan 11 '19 at 22:08
  • \$\begingroup\$ @ElliotAlderson He mentioned that there are two types of questions on an exam that are like this. The NOR and the NAND type ROM cell so we need to learn both. \$\endgroup\$ – EdwardBlackdd Jan 11 '19 at 22:14

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