ROM in a ASIC is bit-reversed

Hi There :

Last month we got the chip from TSMC-fab and most of the things are functioning properly. But the contents of the ROM are stored in bit-reversed fashion.

We have used following ROM memory compiler to generate the ROM file.

**************************************************************************
*Compiler Version : TSMC MEMORY COMPILER 2006.05.00.c.100a
*Technology : 90 nm CMOS LOGIC Low Power LowK Cu 1P9M 1.2V High-vt ROM
*Memory Type : TSMC 90nm low power ROM
**************************************************************************

Due to some mistake in switch selection during memory generation,
ROM contents are stored in bit-reversed fashion in the chip.

1. Does the ROM in the chip, has any internal switch which can be changed to reverse the bits again ?

2. Is there any way to reverse the bits at the chip level ?

It would of great help, if you could help me in this regard.

Thanks in advance,

G S Naveen

Didn't this show up in simulation?

Can't see how to fix it other that with a mask change.

Hi jbeniston :

Thanks.

During simulation, we had used the external ROM initialization file, which was as required. This file was read by the simulation model. The simulation was fine.

We are checking,
1. Whether the simulation model was fine or not ?
2. Whether we had used some other simulation model ?

Suppose that, if there is a switch at ROM-level, which can be used to change the direction of read (bit-reversed), is it possible to change the state of that switch (VCC or GND) on the chip easily ?


BR,
GSN

I wouldn't have thought there would be something in the chip, because that mean each data output would have a mux on it, which would slow it down in 99% of its use.

Is it the Artisan compiler? If so you are supposed to use the memory initialisation file that it generates, not the one that you give to the compiler.

Hi :

Thanks again.

It was tsmc compiler.

Any idea whether there is some option in this compiler or not.