CommunityFDL Main Blog

From mini to mainframe and back again. A programmers journey.

Computers

Back in the 1970s I was going to a community college up here in Cleveland and acquired a student assistant position in the Physics and Chemistry department there. If you said computer to me, I would – like everyone else at the time, I think – get this picture of an IBM card sorter and big tape drives spinning. In other words, I knew nothing of such creatures.

The department owned a DEC PDP 8/i mini computer at the time and I was to be in charge of it. It had two ASR 33 Teletype terminals attached to it. One in the room with the computer and one downstairs for public use. All in the library, of course.

The one in the room with the computer was needed to load the stand alone interpreter which when I came there was FOCAL. But FOCAL had a problem, if your program used any of it’s reserved words as variables it whole thing would crash and come to a halt. Where in one had to go up to the computer room and reload it. By hand. First using the toggle switches on the front to enter the Read In Mode Loader – the machine instructions that told the machine how to read the paper tape on the side of the Teletype terminal. Then load in the Binary Loader by starting the Read In Mode loader. Once the binary loader was in and running, you could then load in the stand alone interpreter. This machine had 8K of memory so that was it.

We decided to ditch FOCAL for this reason and go with a BASIC interpreter instead which was not so brittle.

I moved back down to Florida – for reasons I will go into at a later date – and enrolled in Florida Technological University [now called University of Central Florida] in their Computer Science department as a Computer Science major. Computer support there was much different. They had an IBM 1130 with a line printer and a card reader and punch and a disk drive with 8K of memory. Link. It could run local with a disk operating system with an Assembler and a Fortran compiler but was mainly used as a HASP RJE terminal connected to the big IBM Mainframe at the Univ. of Florida in Gainsville. To run your programs which were on punch cards.

FTU [UCF] also had 4 IBM 2741 terminals that were also attached to the system in Gainsville that ran their home grown interactive system. The interactive system gave you access to a BASIC compiler, a rudimentary editor, an APL compiler and the ability to submit programs to run in batch on the Mainframe and look at the output from. A big step from the DEC PDP 8/i. I learned about IBM JCL [Job Control Language] and some higher level languages like PL/I and Fortran and APL and Algol and various scripting languages. Became interested in operating systems and computer communications [ to become networking]. The HASP multi-leaving RJE protocol was especially intriguing.

Got a summer job at the Orlando Navel Training Center [ now a big condo complex ] programing a Xerox Sigma 7 computer which was attached to a F4E simulator. The Sigma was interesting in that it had an instruction set very similar to the IBM mainframe even utilizing the same I/O instructions. I had take a class on IBM Assembler language previously but got a D in the class. After working on the Sigma, I had become quite proficient at Assembler language and even I/O programming.

From there to a number of assistant jobs one being at the Florida Solar Energy center on a PDP 11/34 that ran RSX 11M OS doing data extraction and manipulation for them from their data loggers. Got full time employment back at the University [now called UCF] initially in the Engineering Department on their PDP11/34 in the Computer lab as well as various LSI 11 micro processors. Then transferred to the Computer Services department where I stayed until retirement. Becoming the lead systems programmer on their IBM mini mainframes running IBM’s VM/CMS OS. Became very proficient at machine level Assembler programming and the use of MACRO programming as well as low level channel I/O programming. That as the computer world changed, proceeded toward micro processors and networking and TCP/IP and writing numerous networking applications as need arose. Becoming the manager and programmer responsible for the email systems and name servers and dial in systems.

In each case though I learned and important lesson. No matter how much you think you understand a system, it’s internals and workings, you can still be surprised. And the more complex a system becomes the more vulnerable it is to failure.

In each case it does not take very much to turn a complex functioning system into a hopeless piece of junk.

It has also become more obvious to me that the complexity of our technical systems – to the point where even those who designed and implemented them do not fully understand how they work. There by leaving them open to all kinds of abuse and failure. So what happened and seems to be still happening to the FDL servers should not come as any big surprise. What should be surprising is how well and how long they do keep functioning.

I also discovered that the general public becomes interested in and begins fooling with technology way before it becomes commercialized. Radio,TV, Computers and Networking were all like this.

CommunityMyFDL Front Page

From mini to mainframe and back again. A programmers journey.

Computers

Back in the 1970s I was going to a community college up here in Cleveland and acquired a student assistant position in the Physics and Chemistry department there. If you said computer to me, I would – like everyone else at the time, I think – get this picture of an IBM card sorter and big tape drives spinning. In other words, I knew nothing of such creatures.

The department owned a DEC PDP 8/i mini computer at the time and I was to be in charge of it. It had two ASR 33 Teletype terminals attached to it. One in the room with the computer and one downstairs for public use. All in the library, of course.

The one in the room with the computer was needed to load the stand alone interpreter which when I came there was FOCAL. But FOCAL had a problem, if your program used any of it’s reserved words as variables it whole thing would crash and come to a halt. Where in one had to go up to the computer room and reload it. By hand. First using the toggle switches on the front to enter the Read In Mode Loader – the machine instructions that told the machine how to read the paper tape on the side of the Teletype terminal. Then load in the Binary Loader by starting the Read In Mode loader. Once the binary loader was in and running, you could then load in the stand alone interpreter. This machine had 8K of memory so that was it.

We decided to ditch FOCAL for this reason and go with a BASIC interpreter instead which was not so brittle.

I moved back down to Florida – for reasons I will go into at a later date – and enrolled in Florida Technological University [now called University of Central Florida] in their Computer Science department as a Computer Science major. Computer support there was much different. They had an IBM 1130 with a line printer and a card reader and punch and a disk drive with 8K of memory. Link. It could run local with a disk operating system with an Assembler and a Fortran compiler but was mainly used as a HASP RJE terminal connected to the big IBM Mainframe at the Univ. of Florida in Gainsville. To run your programs which were on punch cards.

FTU [UCF] also had 4 IBM 2741 terminals that were also attached to the system in Gainsville that ran their home grown interactive system. The interactive system gave you access to a BASIC compiler, a rudimentary editor, an APL compiler and the ability to submit programs to run in batch on the Mainframe and look at the output from. A big step from the DEC PDP 8/i. I learned about IBM JCL [Job Control Language] and some higher level languages like PL/I and Fortran and APL and Algol and various scripting languages. Became interested in operating systems and computer communications [ to become networking]. The HASP multi-leaving RJE protocol was especially intriguing.

Got a summer job at the Orlando Navel Training Center [ now a big condo complex ] programing a Xerox Sigma 7 computer which was attached to a F4E simulator. The Sigma was interesting in that it had an instruction set very similar to the IBM mainframe even utilizing the same I/O instructions. I had take a class on IBM Assembler language previously but got a D in the class. After working on the Sigma, I had become quite proficient at Assembler language and even I/O programming.

From there to a number of assistant jobs one being at the Florida Solar Energy center on a PDP 11/34 that ran RSX 11M OS doing data extraction and manipulation for them from their data loggers. Got full time employment back at the University [now called UCF] initially in the Engineering Department on their PDP11/34 in the Computer lab as well as various LSI 11 micro processors. Then transferred to the Computer Services department where I stayed until retirement. Becoming the lead systems programmer on their IBM mini mainframes running IBM’s VM/CMS OS. Became very proficient at machine level Assembler programming and the use of MACRO programming as well as low level channel I/O programming. That as the computer world changed, proceeded toward micro processors and networking and TCP/IP and writing numerous networking applications as need arose. Becoming the manager and programmer responsible for the email systems and name servers and dial in systems.

In each case though I learned and important lesson. No matter how much you think you understand a system, it’s internals and workings, you can still be surprised. And the more complex a system becomes the more vulnerable it is to failure.

In each case it does not take very much to turn a complex functioning system into a hopeless piece of junk.

It has also become more obvious to me that the complexity of our technical systems – to the point where even those who designed and implemented them do not fully understand how they work. There by leaving them open to all kinds of abuse and failure. So what happened and seems to be still happening to the FDL servers should not come as any big surprise. What should be surprising is how well and how long they do keep functioning.

I also discovered that the general public becomes interested in and begins fooling with technology way before it becomes commercialized. Radio,TV, Computers and Networking were all like this.

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