Model 200 RAM: Difference between revisions
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The model 200 comes with 24k built in, and supports up to 2 more banks of 24k in the form of ceramic dip modules that plug into the Option RAM #1 & #2 sockets. | |||
*[https://oshpark.com/shared_projects/tepuH2VQ PCB | =TANDY 26-3866= | ||
*[http://www.digikey.com/short/ | The original 24K module was Catalog Number 26-3866.<br> | ||
::(1) TC551001 128kB SRAM | This is a ceramic DIP carrier with 3 8k sram chips and a 40H138 to decode A13 & A14 into 3 different /CS for the individual SRAM chips. | ||
::(1) 74AHC1G08 AND gate | |||
::(1) | [[File:TANDY_26-3866_top.jpg|200px|link={{filepath:TANDY_26-3866_top.jpg}}]] | ||
::(29) pins | [[File:TANDY_26-3866_bottom.jpg|200px|link={{filepath:TANDY_26-3866_bottom.jpg}}]] | ||
[[File:TANDY_26-3866.svg|frameless|link={{filepath:TANDY_26-3866.svg}}]] | |||
=Modern Replacements= | |||
https://github.com/bkw777/TANDY_200_RAM | |||
<gallery> | |||
File:TANDY_200_RAM.jpg | |||
File:TANDY_200_Dual_RAM.jpg | |||
File:TANDY_200_Dual_RAM_tsop_14mm.jpg | |||
</gallery> | |||
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This module, designed by Steven Adolph, adds both possible optional 24K banks, for a total of 3 banks when installed. | |||
UPDATE: The pcb and parts below have been replaced by this updated design: | |||
*[https://oshpark.com/shared_projects/o1iXGzr1 PCB] | |||
*[http://www.digikey.com/short/jmq927 Parts] | |||
This is parts to build a single board, although OSHPark will ship you 3 boards. You only need one board for one Model 200 computer. If you want to build all 3 boards, then triple all the part quantities on the digikey cart. | |||
OLD VERSION: | |||
*[https://oshpark.com/shared_projects/tepuH2VQ PCB] | |||
*[http://www.digikey.com/short/q71vcp Parts] | |||
::(1) TC551001 128kB SRAM TSOP32 package | |||
::(1) 74AHC1G08 5-pin AND gate | |||
::(1) 1uF ceramic capacitor, 0805 package | |||
::(29) round pins | |||
This is enough parts to build 3 boards, because you can't order less than 3 PCBs from OSHPark anyway. But you only need 1 board total per Model 200. The single new board takes the place of both ram sockets. You can reduce the part quantities in the DigiKey cart before ordering. | |||
The pins are installed by pulling the pins out of the plastic insulator, and dropping the pins into the holes from the top, then soldering, then cutting off the top. You need 29 pins per board, so one 32-pin stick provides all the pins for one board. | |||
[[File:200_ram_sa_1.jpg|200px]] | |||
[[File:200_ram_sa_2.jpg|200px]] | |||
[[File:200_ram_sa_3.jpg|200px]] | |||
[[File:200_ram_sa_4.jpg|200px]] | |||
[[File:200_ram_sa_5.jpg|200px]] | |||
[[File:200_ram_sa_6.jpg|200px]] | |||
[[File:200_ram_sa_7.jpg|200px]] | |||
[[File:200_ram_sa_8.jpg|200px]] | |||
[[File:200_ram_sa_9.jpg|200px]] | |||
[[File:200_ram_sa_10.jpg|200px]] | |||
[[File:200_ram_sa_11.jpg|200px]] | |||
[[File:200_ram_sa_12.jpg|200px]] | |||
[[File:200_ram_sa_13.jpg|200px]] | |||
[https://photos.app.goo.gl/g1G4bo6FbjJSgcqU2 More Pics] | |||
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=More info= | |||
https://archive.org/details/Model_200_Portable_Computer_Service_Manual_19xx_Tandy/page/n75/mode/2up | |||
http://bitchin100.com/wiki/index.php?title=Tandy_200_RAM | |||
http://club100.org/memfiles/index.php?&direction=0&order=&directory=Steve%20Adolph/T200%20Ram%20module | |||
http://club100.org/memfiles/index.php?action=downloadfile&filename=m200ram.txt&directory=Steve%20Adolph/mods_to_upgrade_ram | |||
Latest revision as of 19:38, 18 September 2022
The model 200 comes with 24k built in, and supports up to 2 more banks of 24k in the form of ceramic dip modules that plug into the Option RAM #1 & #2 sockets.
TANDY 26-3866
The original 24K module was Catalog Number 26-3866.
This is a ceramic DIP carrier with 3 8k sram chips and a 40H138 to decode A13 & A14 into 3 different /CS for the individual SRAM chips.
Modern Replacements
https://github.com/bkw777/TANDY_200_RAM
More info
https://archive.org/details/Model_200_Portable_Computer_Service_Manual_19xx_Tandy/page/n75/mode/2up