Timeline for Did ROM chips jump from 8K to 32K?
Current License: CC BY-SA 4.0
9 events
| when toggle format | what | by | license | comment | |
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| May 24 at 15:29 | comment | added | supercat | @user71659: If one had 16K of code and was making a 32K device, one could write two copies of the code and arrange so that either could be selected based on bonding-wire placement. | |
| May 23 at 21:28 | comment | added | Solomon Slow | @user71659, I wasn't talking about binning. I was talking about the possibility that the total cost of manufacture might be less if they used the same tooling for "16K," "32K," and 64K parts. I am not in the business, so I don't know if that's a realistic possibility or not. Obviously, if you used different tooling, then you could make more 16K dice per wafer than you could do for 64K dice, and maybe that would dominate the equation. | |
| May 23 at 20:58 | comment | added | user71659 | @SolomonSlow Remember that these are mask ROMs. You can't remap or mark area bad after production, so binning is not a factor. | |
| May 20 at 23:25 | comment | added | Frog | @Solomon Slow - indeed, you might expect that a good proportion of faulty 64k dice might work as 16k devices with the spare address lines strapped one way or another. | |
| May 19 at 20:54 | comment | added | Solomon Slow | @Frog, Right. I would not have recalled "JEDEC." I was only ever a software geek. But, I expected that larger ROMs would have the same pinout, except with one or both of those "NC" pins connected to address lines. My point though, was that if I had the capacity to manufacture 64K chips, and you ordered a 16K chip, You might never know that the parts I delivered actually contained 64K dice, but with two of the address inputs internally connected to ground (or Vcc, doesn't matter) instead of being connected to the "NC" pins. | |
| May 18 at 1:15 | comment | added | Frog | @Solomon Slow I believe the pinout is a JEDEC standard, so the NC pins would be used for larger capacity devices | |
| May 17 at 18:52 | comment | added | Solomon Slow | I notice that the package has two NC pins, both of which are adjacent to address input pins. Now, I'm not saying that I have any knowledge whatsoever of how that chip actually was made, but if I were the manufacturer, and if I had a 32k part in my catalog, and if the marketing department said I must also offer a 16k part, I'm pretty sure I would not design a whole new chip to satisfy that requirement. | |
| May 16 at 15:46 | vote | accept | rwallace | ||
| May 16 at 11:18 | history | answered | David | CC BY-SA 4.0 |