SAP - 1
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Author : Satvik Ramaprasad

Project access type : Public

Description :

Simple as Possible Computer
You can program the ROM to do simple operations like addition and subtraction. To run the program, set the clear input to ground. 
The ROM currently performs 5+11-6. 
Instruction OP-Code
  • LDA       -  0x
  • ADD      -  1x
  • Subtract - 2x
  • Output   -  ee
  • Halt        -  ff
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Comment deleted by abc.

Posted on Mar 15 2018 at 04:30AM UTC. Last modified by abc on Mar 15 2018 at 04:30AM UTC.

Very cool. Thanks! I am working on modelling a rotating drum sequencer Like those that preceded the IBM 650. This is a great reference.

Posted on Aug 30 2018 at 07:06PM UTC.

this is righteous

Posted on Nov 27 2018 at 01:34AM UTC.

This is cool ,but why does the program counter count 0 8 1 9 2 A... instead of 0,1,2,3,4...

Posted on Jan 16 2019 at 01:50PM UTC.

@Aiex2 it seems like it's simply splitting the ROM into two portions. The top two rows of hex entries are the instructions,

while the bottom two rows are the numbers. This way, it's better organized. It would be pretty hard to wrap your head

around instructions if they were sequential.

Posted on Feb 25 2019 at 03:38AM UTC.

How were the C39, C40, C41 and C43 names chosen? What logic is there behind them?

Posted on Apr 20 2019 at 01:50PM UTC.

David Stevens This sap circuit was taken from the Logisim implementation of the same.

Posted on May 02 2019 at 09:20AM UTC.

Comment deleted by herty10.

Posted on May 24 2019 at 09:37PM UTC. Last modified by herty10 on May 26 2019 at 02:11AM UTC.

Maybe @DavidStevens Those are models of stuff and those ones worked.

Posted on Nov 18 2019 at 06:12PM UTC.

Hi, I'm also developing a simple computer but I don't understand most of the stuff you put there.

Posted on Dec 19 2019 at 12:25PM UTC.

My best guess at the nomenclature for C39-43 has to do with the encoding of instructions each segment performs. To back this statement up some, take a look at CS-SAP. In it, each sub-circuit is used to re-encode the decoded instructions that are fed from the iDecoder (instruction decoder), and the control signals from T-Clock. As to the exact instruction pattern that this nomenclature follows, I haven't the foggiest.

Posted on Feb 26 2020 at 10:26PM UTC.

How did you even manage to program the ROM? ROM cannot be modified, are they?

Posted on Dec 01 2020 at 12:34PM UTC.

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