Hi all Friends,

I don't know about PAL programming,

What is PAL programming (for example current i have PALCE22v10) and where i found documents, I search google but not enough.

Thanks for advance,

Regards,
Posted on 2003-05-02 03:08:45 by CYDONIA
PAL is a more specific area, try with PLD instead, its more generalized.
btw, what do you mean with programming? the software or the hardware? i guess the hardware, didnt it?
Posted on 2003-05-02 06:52:43 by dion
A PAL is a Programmable Array Logic. It consists of an array of logical devices such as AND gates, OR gates, flip-flops, etc. Programming involves connecting these gates to each other through internal fusible connections that are burned. A program is used to generate the fuse pattern.

Most of the elements are assigned a number such as A1 and A2 for an input to an AND gate. It's output might be B1. So, when programming the gate, you would enter B1 = A1 AND A2. Then you could take another gate and program it to use B1 as its input.

I've simplified that quite a bit because the inputs and outputs in most cases can be negated. Such as /A1 AND A2 = /B1.
Posted on 2003-05-02 07:48:47 by drhowarddrfine
Hi,

btw, what do you mean with programming? the software or the hardware? i guess the hardware, didnt it?


Thanks Dion, :)

I'm newbie about PAL subject. I have a 68HCXX trying board. But manufacturer firm used a PAL chip on the board. I don't know why used PAL chip. I was think PAL chips like 93cXX series, but i to be mistake. :)

Thanks for help drhowarddrfinedrhoward,

i understand now about PAL chips. I think all operations bit level. Correct? Do you know any util or compiler/simulator for programming /adjusting gates?

Regards,
Posted on 2003-05-02 09:08:39 by CYDONIA
What you are programming is a huge truth table to emulate a logic devices.

Regards, P1
Posted on 2003-05-02 12:21:16 by Pone
I bet you that the PAL chip holds the equivalent to BIOS for your 68HCxx.

Once you 'fuse' your logic its fixed and pernament. By their nature, you can have them act like a ROM, where sequentially giving them an address, and receiving a byte out from 8 output pins. The outputs will vary like accroding to the address. The output value is the logical result of the fusing.

There is also a PLA (brother to the PAL). The difference is suttle. If memory serves me, PAL has AND gates followed by an OR gate on each output pin. PLA has the reverse....

:NaN:
Posted on 2003-05-02 16:40:54 by NaN
i learn from you too, CYDONIA :grin:

i tend to agree with what Pone said. PAL was actually a type. i.e. PALCE16V8, 20V8A, etc..
dont know if i'm wrong, but i think that "PAL" term taken from this :tongue:
other type is GAL, for instance.

yes, it is a huge logic gate array, so you can do whatever function you want. but i dont agree with NaN, that its like a rom. if you read the TTL logicbook, you'll find why it is different and cant be compared.

why someone using PAL btw?
well, that's a somehow a parody. a designer dont want his design was copied by others, so he uses PAL and "lock" it. but, in repair technician like me perspective, i was burdened to buy his PAL if the PAL chip on his board was broken . yes, not all company locking its PAL chip, but most do. so what we gonna say? its up to you.

unfortunately i dont know about the software. try google. i just know how to copy n replace a bad one with a good one :grin:
Posted on 2003-05-03 06:51:26 by dion
Im not saying it IS a ROM, im saying it can be made to ACT like a rom.

I dont want to fuss over words.. i will draft up some schematics for everyone.
Posted on 2003-05-03 10:50:43 by NaN
Here is a PAL layout (99% sure its a PAL not the PLA):

PAL -- Programmable Logic Array. You get just that.. Logic arrays.

They are designed with different sized arrays for different uses. For thing like ROMS like behaviour, they tend to have very large AND arrays (for addresses) and only 8 OR arrays (for data out).

In the lower diagram, i have "fused" with red dots. To provide:

Addresss A0-A7 == 0x81
Output B0-B7 == 0x36

Addresss A0-A7 == 0x82
Output B0-B7 == 0x0F

Addresss A0-A7 == 0x83
Output B0-B7 == 0x70

I hope this clears the confusion. They can be made to perform logic and state machines as well. Some come with Flip Flops on the output "B" lines allowing you to do this, and feed back the outputs into the inputs. This is another application that could be used for PAL's. (not shown below, but should be ez to see how it would work).
Posted on 2003-05-03 11:24:05 by NaN
PALASM may help get you started.
Posted on 2003-05-03 13:32:40 by alpha
http://www.ee.latrobe.edu.au/~djc/PALS/SMALL_PALS.htm nice programmer shemas, pdf and links

Regards,
Posted on 2003-05-05 00:35:52 by CYDONIA