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# bitslice architecture

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#### dsp_

##### Member level 3
bit-slice microprocessor design mick brick pdf

i heard of it one time .. dont know where
but i got curios about it and now i want to know what its exactly
is it true that its some kind of cascaded logic blocks for each bit ?
is it also true that its rather expensive and was the only solution for very fast computation about ten years ago?
is it a future or an "ancient" technology?
makes it sense to use it on an fpga?
i googled it, but i didnt find much information about it .. only that there are some publications by a german called Arndt Bode
someone knows where to get some of them?

dsp_

Bit-slice design is a way to deal with combinational arithmetic logic which is to difficult to handle for full-wide inputs. For example, to design 8+8 bit adder you have to consider truth table with 2^16 possible inputs what is too expensive in the terms of time and area of design. For this purpose you can use bit-slice approach: you can design 1-bit adder and then combine some of these adders to the more complicated structure. Also, sometime this approach is used to build Alu. It was well defined in the Katz' book Contemporary Logic Design. This book was uploaded to Elektroda, or just for main idea you can use this link:

Ace-X.

hi ,
can anyone tellme what exactly is the difference between an ALU and an FPu .

smartkid said:
hi ,
can anyone tellme what exactly is the difference between an ALU and an FPu .

Are you joking? Thit is the question for first-level school.

ALU is Arithmetic-Logic Unit
FPU is Floating Point Unit

So, the difference is the set operations the block is intended for. If it is just simple addition, subtraction and some word-wide logical operations - it is ALU. If also floating-point operations are supported [or ONLY floating-point operations] - this is FPU.

dsp_ said:
he am29xx modules are the only bitsliced cpus/alus i've found yet ...

Not only - there were a lot others like I-3000 from Intel or MC-1800 from Motorola. Actually, they were not only bit-sliced, but also microprogrammed [NOT microprogrammed as modern microcontrollers! They used idea of Maurice Wilkes about flexible set of commands].
I had somewhere the ebook about all this stuff, so I could send it to you if you are really interested in this topic.

Ace-X.

by microprogrammed do you mean that they already had microcode which decoded opcodes to microinstructions(fetch,increment program counter)?

are u still talking about contemporary logic design
Ace-X said:
theres just a pdf compilation of html files

have u got this version?
i think it'll look much nicer
but probably i should wait on the second edition and buy it =)

http://www.cs.washington.edu/homes/gaetano/cld2/

TIA
dsp_

Hill , ISBN 0-07-041781

This the best book on bit-slice technique of computer implementation I've read
It is based on Am29xx series of devices although there is another newer series
Am29xxx

dsp_
No, I told about "High Performance Computing" by Kevin Dowd. It has nice introduction to the history of microprogramming.

Well, one more useful link with the implementation of bit-sliced microprogrammed unit: **broken link removed**

Ace-X.

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