| ??? 02/20/07 05:59 Read: times |
#133279 - rather than "wierd old ROM" why not part number? Responding to: ???'s previous message |
Hmmm ... Sam Sudonimm ... cute but not spelled right ... is that what you intended?
Tell us what the manufacturer and part number are. Someone probably knows what to do. I was professionally active in that era, but don't remember any devices that required 9-volt logic levels. Could this be DTL? Maybe that's not what you have, but please, provide ALL the relevant information. Be sure you know what you're proposing to do. If it's not really a 9-volt part, it will be DEAD! If you interpose schottky diodes (anode to the ROM, pulled up to the ROM's Vcc) between your drivers and the ROM, or drive the address/control inputs to the ROM with open-collector drivers, e.g. 7407 or nearly any other O.C. driver capable of higher output voltage levels than its own Vcc, and pull them to Vcc=9V through 4K7 pullup resistors at the ROM, that should do the trick. You can read the data through resistive voltage dividers, e.g. a 390/470-ohm divider. RE |
| Topic | Author | Date |
| 9 volt to 5 volt bidirectional logic interface? | 01/01/70 00:00 | |
| rather than "wierd old ROM" why not part number? | 01/01/70 00:00 | |
| if you need to use a misspelled pseudonym | 01/01/70 00:00 | |
| TI TMS6100 speech synthesis ROM | 01/01/70 00:00 | |
| my bad | 01/01/70 00:00 | |
| NXP bidir level shifter appnote | 01/01/70 00:00 | |
| Easy ROM interface | 01/01/70 00:00 | |
| something similar just occured to me | 01/01/70 00:00 | |
| Current limiting resistors | 01/01/70 00:00 | |
| great, I think I've got it | 01/01/70 00:00 | |
| read the datasheet twice ... | 01/01/70 00:00 | |
| voltage question and datasheet errata | 01/01/70 00:00 | |
| Why Vss is positive and Vdd is negative | 01/01/70 00:00 | |
what I meant was ... | 01/01/70 00:00 | |
| RCA/Intersil micro can do 11V | 01/01/70 00:00 | |
| and there was that 1 bit micro... | 01/01/70 00:00 | |
| device programmer, tester | 01/01/70 00:00 | |
| naw ... just use the old RS232 level shifters | 01/01/70 00:00 |