FOUR CHIPS SOLDERED TO REAR OF BOARD
The last four ICs - 74LS03 open collector gates - were soldered onto the board. These plus the four similar chips on the front of the board are the drivers of the 16 data lines, 15 address lines and the I/O Entry Sample signal that are connected to the IBM 1130.
The remaining chips on the board are the state machine logic, a driver to request the cycle steal from the 1130, and interfaces that watch 1130 signals such as X6, Run and Cycle Steal Level 1.
DISCRETE CAPACITORS AND RESISTORS SOLDERED ONTO THE BOARD
Two pullup resistors are used to construct three and gates from spare open collector buffer gates, rather than installing an additional IC to implement the gates. Thus, the output is high when both inputs are high, pulled up by the resistor, but if either input is low the open collector gate will pull the output down to ground. A third pullup is used with an open collector nand gate to convert it to normal gate operation.
Decoupling capacitors are installed near every IC, plus filtering capacitors were used on the two voltage regulator chips.
THE ONLY REMAINING COMPONENTS ARE CONNECTORS
Most connectors are standard 2.54 mm spacing header strips, used for my cables to the 1130 as well as to connect this shield to the Arduino Mega 2560, but there is one screw terminal connector where the +12V and ground from the IBM 1130 is delivered.
Carl, as a junior at Murray State University, I designed and debugged a DMA interface between a Kennedy 9-track tape formatter/controller and an IBM 1130. I also designed and built a SAC II channel multiplexer. These babies actually worked. Your blog leaves me with "warm and fuzzies". I live in Atlanta, so I guess I won't get to play with you in the shop. You sure a tenacious individual! God Bless You!
ReplyDeleteMy own 1130, as contrasted to the VCF 1130 I am restoring, has the SAC installed. I built a facility connecting to the SAC interface that implemented virtual 2310, 1442, 2501, 1132, and 1403 devices, loaded core via DMA, even had a shadow 1052 that would capture digital hardcopy from the console printer.
ReplyDeleteSince you worked with SAC you know how generalized the interface is.
Atlanta and Satellite Beach aren't immeasurably far apart, so there exists the potential for some future time-limited workshop joint hijinks.