Author Topic: EEVblog #1021 - Retro Radio Shack TRS-80 Color Computer  (Read 2475 times)

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Offline Kleinstein

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Re: EEVblog #1021 - Retro Radio Shack TRS-80 Color Computer
« Reply #25 on: September 14, 2017, 02:14:45 AM »
There was a portable TRS-80 (https://en.wikipedia.org/wiki/TRS-80_Model_100) that used SRAM, however this looks more like based on the original B&W TRS80.

SRAM had a significant price tag, and only got low power in the CMOS versions. The CMOS versions were really low power, but AFAIK only available later.

With all the interfacing / refresh integrated in the 6883 (= 74LS385) it is easy to use DRAM. So this simple looking 74LS... is a really important part for the CoCo - it's the chip that holds things together. The whole circuit looks a lot like the typical circuit in the 6883 data-sheet.
 

Offline edavid

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Re: EEVblog #1021 - Retro Radio Shack TRS-80 Color Computer
« Reply #26 on: September 14, 2017, 02:27:26 AM »
With all the interfacing / refresh integrated in the 6883 (= 74LS385)...

Actually 74LS783.  I wonder why they bothered with a 74 number, since there was no second source.

74x385 is a quad serial adder/subtractor  :)
 


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