Wednesday, July 13, 2022

An important question is how the museum can best use and demonstrate this 1130

THE MACHINE AS IT WILL SIT AFTER RESTORATION IS OVER

This particular machine has the standard keyboard, console printer (typewriter) and cartridge disk drive. It was configured to attach to an optical mark reader device, but that is not part of the system now. No other peripheral device controllers and connectors are installed. It did not come with a disk cartridge and would need one in order to boot up the Disk Monitor System (DMS) that controls the system. 

STILL FALLS SHORT EVEN IF A SUITABLE MONITOR DISK IS AVAILABLE

The 1130 comes from the batch processing era, where a sequence of single jobs are submitted to the machine and run serially. Most often these were input on punched cards while the output of the job was usually printed on a 1132 or 1403 line printer. 

A special cold start card is put in the card reader, the Program Load button is pressed, and DMS is brought in from the disk cartridge and begins running. DMS will immediately print a banner page on the line printer and then begin reading punched cards on the 1442 or 2501 reader to process jobs 

We can get around the lack of a cold start card by using my Memory Load Tool to load the contents of that card into core so that it can be executed, causing it to read from the disk drive to load DMS.

Since we have no card reader and no line printer, DMS will immediately go into a wait indicating that the line printer is not ready. When the hopper of jobs in the card reader runs out, DMS waits indicating that the card reader is not ready, but it won't get to that point because of the printer.

SOME ALTERNATIVE WAYS TO OPERATE AN 1130

A low cost alternative existed supporting paper tape, where the input would be on the paper tape in the 1134 reader and even more rarely the output would be punched on paper tape on the 1055 punch. Minimum configuration for DMS does not require a card reader nor a line printer. One can use paper tape peripherals to submit jobs and have the results punched out on the 1055. 

It would be quite cumbersome as one would need some offline device to read the tape just punched and print its contents, but it is at least possible according to the design of DMS. 

There is also a method to deal with a temporary failed line printer - a control card can be input in the card reader that directs the system to print the output on the console typewriter rather than the line printer. There is also a control card that will tell DMS to read from the keyboard rather than the card reader or paper tape reader. This would be very tedious to use, but it is possible.

ADDRESSING THE DISK CARTRIDGE ISSUE

I have quite a few disk cartridges and intend to archive the data on them, after which I could set up one with DMS and suitable programs for the museum. That way they could bring up DMS, assuming their is a resolution to the lack of input and line printing output devices. 

An alternative that I have been exploring is modify the internal disk drives of an 1130 with a device I would create plus a very few wiring changes, allowing the drive to run in either real physical disk mode or a virtual mode. The disk cartridge for virtual mode will be a file on an SD card inserted into my device. Any disk cartridge, whether damaged or good, would be inserted in the drive. In virtual mode, it will still begin spinning and the drive will move the disk arm in and out just as if the heads were reading and writing, but I would have blocked the heads from physically lowering onto the disk surface.

My device would provide the signals that otherwise would be read by the disk heads from a physical cartridge. My device will capture any written data that is going to those heads and update the virtual cartridge file. In this way, the disk heads and cartridge need not be at risk since there is no contact between them. Still, the machine gets to read and write to a (virtual) disk cartridge and the operator of the machine hears and feels the spinning and the disk arm seeking during operation.

In order to protect the precious heads and cartridges, I would build one of these for my own 1130 as well as one for this museum machine. I suspect that two or three other museums with restored 1130s would be interested in these as well. 

I will be sharing the contents of all the disk cartridges I own and archive, plus people can use the IBM 1130 simulator on a PC to build and modify other cartridge images. 

ADDRESSING THE LACK OF PRINTER AND INPUT/OUTPUT DEVICES

Typing on the keyboard and seeing output on the printer is possible but quite limited. Imagine typing in an entire Fortran program plus monitor control cards, most of which are sensitive the columns used on a card, then waiting for a Selectric typewriter to type out hundreds of lines of listing compilation messages and program output. 

Still, this is something that I know I can make work. I would need to work with the IBM 1130 simulator or my own 1130 to figure out what changes are made in core and on disk when the monitor commands to use the typewriter and keyboard are issued. I could then zap the disk cartridge image so that when the machine is booted up with that image it thinks it just read those cards. It would immediately type the banner on the console printer than select the keyboard waiting for the first 'card'.

I can build real or virtual paper tape devices, but would have to update the 1130 to add the device controller circuitry for the 1134 and 1055. The devices themselves aren't that complicated, but the controller logic consists of 26 SLT cards that are not presently in the system. I don't even know if the backplane in the compartment (gate A compartment B1) has the traces between card slot pins to implement this all. 

If the 26 necessary cards are in the big box of spare cards and the backplane can at least be completed by wirewrap, then I MIGHT be able to 'install' the paper tape reader and punch features. Working with paper tape will be much less clunky than working with the keyboard and typewriter. 

FALLBACK FOR DEMONSTRATION PURPOSES

I could build a disk cartridge (real or virtual) with some demonstration programs such that minimal typing on the keyboard is required to fire them up. Those programs can be ones that use the console printer and keyboard - many interactive games for the 1130 fit this bill. That way I don't need the paper tape controller circuitry nor the devices, but some useful operation is still possible. 

7 comments:

  1. Carl, The DMS 2 listings are available that should make it easier to find out what it’s doing on this.

    Sadly, it appears I had to enable third-party cookies to post here.

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    1. I do have the listings, the source code and binaries but it is actually quicker to use the simulator to dump memory right after bootup, then read in the cards to move output to the console printer and input from the keyboard, after which another dump can be issued.

      A quick read and compare of the two dump files will flag all the words that have changed. Similarly I can compared the disk files to see if it writes anything on the disk when the commands are read.

      Not much I can do about the third party cookies, since I get the hosting and blog editing at no cost from blogspot.com/blogger.com

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  2. Could you build a virtual interface for the machine? Like a web site where a user could drag a job to the machine and the output file would be sent back?
    Virtual Card Reader/Virtual Printer?

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    1. Hi Bob

      If this machine had the Storage Access Channel, like my machine does, I could implement virtual printers, readers and other devices exactly as you are imagining. Without the SAC it is not feasible, alas.

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  3. I think your idea to build a Disk Simulator is brilliant. Give it a three-way option switch for physical seek (real access arm motion and sound), simulated seek (no physical motion but duplicate seek and sector delay periods to emulate original access speeds), and no-seek (data-ready instantly on all accesses). The latter because it would be fun to know how badly the slow seek impaired 1130 processing time.

    However, the DMS reliance/insistence on card input and printer output are a major problem to making the machine usable. Would it be impossibly difficult to provide an SD-card-based emulator for the card reader? Or a single I/O collector that could stream card-in, printer-out data to an attached PC?

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    1. Hi David

      The challenge is that the circuitry to recognize the IO instructions and drive a printer or reader are not installed in this machine. It would take many dozens of SLT cards and perhaps major rewiring of the backplane to create the drivers and signal lines that i could then link to for virtual devices.

      The SAC feature makes it easy. Without the feature you need the real device controllers, even if the peripheral is missing.

      For example, this machine has the 1231 Optical Mark Reader device controller logic installed. Even though there is no peripheral to attach to it, it would be possible to make a virtual 1231 and use it with the 1130 system.

      While nothing is truly impossible that doesn't violate the laws of nature, it is very infeasible. Heart-Lung surgery plus brain transplant, and even that understates how intrusively it would have to be modified to add devices without the SAC feature.

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