Monday, May 30, 2016

1442 reads fine, cornering still not right; 1053 problems mitigated; starting on memory expansion


My challenges with the 1053 related to a few areas. First, the space button sometimes caused a tab. Second, the carrier return sometimes jammed past the left margin. Third, sometimes the tab movement didn't unlatch where it stopped. Fourth, line feed sometimes stuck on for a few cycles.

The carrier return problem was a real challenge. No settings or advice from the maintenance and theory of operations manuals gave a clue as to why this happened and how to stop it. Further, the illustrated parts catalog and the diagrams in the maintenance manual did not match the part on the carrier which engages with the margin, so I couldn't see how it should appear.

The resolution was to remove the part on the carrier and reason out how it would have to perform in order to work properly. That finally led me to realize that a slanted bar on the part was bent out of position. When I restored the bar to its reasonable position, the latch which allowed the carrier to pop over the left margin will not do an absolute stop.

Testing proved that the return will now work right, without wedging behind the left margin. I worked on the tab and space issues and determined that these were residual lubricant issues which will work out of the mechanism with more use.

Specifically, the tab levers on the carrier are meant to snap all the way back when the carrier reaches a tab stop, but the old oil keeps the part from pivoting smartly in some cases. When it doesn't pivot all the way, it remains with the tab movement unlocked, so even the use of the space button will trigger a tab movement. Once the tab movement locks, as it does most times, space causes just a single space movement of the carrier.

Line feed is similarly symptomatic of residual old lubricants still being moved out of place by new oil. The cure for all of these is use - more tabs, spaces, returns, line feeds and backspaces will eventually yield a correctly operating machine, with symptom occurrence rates asymptotically decreasing to zero over time.

I have to string the ribbon color shift tape onto the machine, repair one lever that selects single versus double spacing, and put the covers back on the typewriter. Once that is done, it can be lowered into place and will be considered finished. The color shift tape will take a bit of adjustment to get right, of course, and the process of replacing the covers is awkward to say the least.


I fired up the 1130 system and tried a Program Load of a boot card through the 1442 card reader. Success would be seeing all eighty columns transferred correctly and no error checks on the reader. I met that goal - I can boot various cards without error.

Beyond the ability to read a card without error, the cornering station and stacker adjustments need to be completed so that cards will reliably move all the way through the machine and out into a stacker. This still needs finessing. A bit more than half the time, the card is sent to the stackers, but otherwise it hangs up in the cornering station causing a check condition.

I also found that the mechanism to select stackers is a bit dodgy, so that sporadically I will get a card wedging up at the exit rollers on the far stacker. This damages the card as well as causing a check stop. I suspect that the cards are entering the stacker area on a slant, which cocks them various amounts. Rotated too much and the card edge will block on one of the two rollers and fold over.

This all comes down to adjustments of the cornering station and stacker. When that is right, I expect everything on the reader to be right (ignoring the broken punch unit).

pushrod wedged and cracking off ceramic on previously intact wheel

I began more detailed design work and determined that my connections to the board are via a pair of old-style .125" spacing edge connectors, double sided, 40 per side or 80 per connector. It is a holiday today but I can pick up the connectors tomorrow and start wiring them up for signal, control and power. The goal will be to use an FPGA to exercise and test the memory, also to prove out operation they way I intend it to work.

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