Sunday, March 15, 2026

Constructing the new 1130 MRAM board today, part 1

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FIRST STEP WAS THE POWER SUBSYSTEM I installed the two linear voltage regulators which drop the 12V input power to deliver the two power rai...
Saturday, March 14, 2026

Redesigned 1627 Plotter controller card while waiting for my MRAM board and parts

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WAITING ON ALL PARTS TO ASSEMBLE THE NEW 1130 MRAM BOARD I already have the printed circuit boards from JLCPCB and most of the components fr...
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Wednesday, March 11, 2026

1130 MRAM testing observations while I wait for the new board for the updated design

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PCB AND PARTS ARRIVING ON MONDAY I had redesigned the board to utilize an FPGA to drive all the timing, dropping the use of timer chips and ...

Looking at 6V regulator SMS card to resolve 1130 power issues - part 3

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CIRCUIT OPERATION TO MAINTAIN 6V OUTPUT VOLTAGE The comparator that controls the voltage of the 6V supply is formed with a pair of 026 trans...
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Tuesday, March 10, 2026

Watched pot syndrome - can't get the 1130 6V power regulator to trip now that it is instrumented

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REMINDER OF THE 6V REGULATOR ISSUE The 1130 logic rails are +3V, +6V and -3V in addition to some special voltages for other purposes. DC is ...
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New rotate and tilt tapes for the 1053 typewriter of the System Source Museum's 1130

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TAPES SNAPPED ON THE CONSOLE PRINTER OF THE SSM 1130 The console printer (1053) of the 1130 computer is based on the IBM Selectric typewrite...
Sunday, March 8, 2026

Code written and simulated for FPGA in new 1130 MRAM core memory replacement design

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ROLE OF THE FPGA The FPGA produces all the control signals that drive the other chips on the PCB. I can update the FPGA and modify the contr...