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Topic: More than 256K of memory? (Read 6676 times) previous topic - next topic


The classic 8051 processor contains 128 bytes of RAM.
But we're talking code space, aren't we?  PIC10F200 has 256 words of program and 16 bytes of "RAM" (and very few "registers, but it does have some hw stack.)  Atmel ATtiny4 has 256 words of program and 32 bytes of RAM, plus some registers.   In the AVR case, 256 words of program works out to 512 bytes; for the PIC10, an instruction word is only 12bits...

Nick Gammon

Please post technical questions on the forum, not by personal message. Thanks!

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Nick Gammon

I withdraw that comment. The early processors (eg. 6800, 6502) had no RAM as such. But you wouldn't operate them without RAM on the bus.
Please post technical questions on the forum, not by personal message. Thanks!

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Coding Badly

There is at least one Atmel AVR ATtiny processor with no SRAM.  The one I looked at has three "slots" for return addresses so CALL (barely) works but it otherwise has no memory.  All data has to be kept in registers (32 bytes) (or EEPROM).


No doubt!  "ATtiny" is apropo.


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Feb 25, 2013, 10:44 pm Last Edit: Feb 25, 2013, 10:51 pm by JoeN Reason: 1

Since we are pressing on without the pleasure of the company of the OP, I was reading yesterday about how one of the first gaming consoles (or devices anyway) only had 128 bytes of RAM, because it was so expensive. It might have been Pong. So each frame refresh, the entire playing field had to be generated from scratch, because it couldn't be stored in RAM.

The Atari 2600 had no video memory.  The video signal out was generated on the fly.  This was not just pong, but for every game that ran on this system.  I think it generated an interrupt when a scanline needed to be started for output to the TV and then it was up to the CPU to provide the data on the fly.


A lot of vector games worked this way too.  For vector monitors this makes total sense because the main program has control of the electron gun and doesn't even have the constraints of timing, except how many inches of line it can draw between refresh cycles.
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