[author : Tim Scully] #Listing #Assembly #Programming
Extract : « [...] As I was working on these modifications to PILOT, my computer grew in capability by the acquisition of two SA400 disk drives. This logically led to the addition of instructions for disk loading and saving of programs. My system uses several cards designed by Polymorphic Systems Inc., and shares a common property of Poly systems: low memory is dedicated to ROM and system software, leaving application programs in higher memory addresses. So I reassembled Dr. Starkweather’s PILOT to a higher address space, beginning at 3200H, together with my additions to his software.
The bulk of Dr. Starkweather’s program is unchanged, except for reassembly to a different address space. The modifications which have been made can be considered in two groups: those peculiar to the Poly disk system, and those which could be useful on any 8080 system. The table CTLST has been expanded and somewhat modified to include these two groups of changes. [...] »
[author : Donald J. Ingraham] #TradeAndLaws
Extract : « On Computer Crime Bill S240 (DDJ # 37), Jon Taber shrilled the clarion to resist the enactment of the Federal Computer Crime Bill, and before everyone abandons the keyboard for the barricades, I thought-as a prosecutor-it might be helpful to hear from the other side.
In one sense we are allies, Taber and I, because as an employee of a local D.A., living in and accountable to our community, I do not think a Federal statute is needed. The enactment of S240 would permit defense counsel to argue preemption, the legal doctrine which precludes States from enforcing copyright, postal fraud and some other laws, on the theory that the availability of the Feds excludes States and local relief. Particularly in computer-related crime, my experience is that Federal preemption would deny protection to the smaller victims, and that anything smaller than Rifkin would not be accepted for prosecution because of U.S. Attorney budget restraints. Besides, we local firms like to help on local problems. [...] »
[author : Jon Taber] #TradeAndLaws
Extract : « I read Mr. Ingraham’s response to my article with interest, especially since he is chairman of the California District Attorneys Association Computer Committee. I was disappointed that he chose not to reply point by point. A response such as this would be helpful. I am not trying to be unreasonable in opposing computer crime legislation; if I am in error, Mr. Ingraham is cordially invited to demonstrate it for everyone’s benefit, including my own. [...] »
[author : B. W. Lee] #Language #Programming
Extract : « The aim of this series of four articles is to introduce STOIC as a programming language and as a program development system. This and the next in the series will cover the basic structures, syntax, and operations of the language and provide examples of their usage. The third in the series will describe the features of a specific implementation of STOIC for 8080/ Z80 microcomputers based on the North Star Disk as the mass storage medium, the operations of the STOIC display editor, and the STOIC file system. The fourth and closing article will cover the modular extension packages for double precision integers, floating points, and complex FFT, with examples to illustrate their usage and applications.
WHAT IS STOIC?
The STOIC is an acronym derived from: STack Oriented Interactive Compiler. Depending on the context in which it is used, STOIC refers either to a program development system or to a programming language. [...]
As a programming language, STOIC is nearly identical to FORTH in structure and syntax, but where FORTH is lean and skimpy, STOIC is baroque in its explicit support of a large number of data types with lavish sets of intrinsic functions and predefined operations. [...] »
[author : Gregg Marshall] #Language #Listing #Programming #DataAcquisition
Extract : « This manual is an introduction to the programming language DAL, which stands for a Data Acquisition Language. DAL is a very simple programming language. However, it provides everything needed for its application: data acquisition. [...] »
[author : H. T. Gordon] #Listing #Assembly #Mathematics
Extract : « My first effort at generation of a sequence of pseudorandom numbers (DDJ # 32) was primarily aimed at minimizing the time required to generate successive 8-bit binary numbers. The basic logic outputs a non-repeating sequence (NRS for short) of all 256 possible numbers. This “core” sequence can be transformed into a limited number of variants by simple mathematical operations. Such variations can be concatenated to yield a longer NRS. However, this logic entails a great sacrifice of the quality of the numerical sequence, that is easily recognizable as non-random and is not difficult to decipher. [...] »
[author : L. Moore] #Listing #Assembly #Programming #Diagnostic
Extract : « While memory dumps may be helpful in some debugging applications, there are occasional instances where one must use a file dump to ensure the contents are as expected. The following program, written for the SWTP 6800 system, is such a dump. It uses the FLEX operating system. The layout of the dump is similar to those produced on most large IBM systems, hexadecimal followed by the ASCII equivalent. Where a particular hexadecimal pattern does not correspond to a valid ASCII printable character, it is replaced by the period (.) prior to printing. »
[author : Lee Felsenstein] #Display #Graphics
Extract : « I am trying to find a home for an orphan design. The VDM-2 currently exists as a prototype S-100 printed circuit built partly to specifications set by Processor Technology, which so recently made a meteoric attempt to achieve greatness by liquidating. Being but a simple engineer, I stolidly completed the design (with a few small changes) and displayed the result at SigGraph recently. Now it remains to find a manufacturer, especially one who will agree to make a version available as an S-100 Sol retrofit. [...]
The VDM-2 was designed as a sophisticated 80 X 24 text display for use in Sol and other S-100 computers. Of prime importance in setting the specifications has been the desire to allow for the fullest use of the graphics-related capabilities inherent in the memory-mapped type of display. In addition, provision has been made in the hardware for use of the VDM-2 in an extended video environment.
Graphics-related capabilities include the alternate writeable character font, row-column screen addressing, contiguous accessible video in both dimensions across the screen and “glitch-free” CPU access.
Alphanumeric features include extended attributes such as underline, half intensity, blinking and font select, ROM resident character set using EPROM-compatible character generator, selectable character or cursor blink, selectable text line modulus and smooth scrolling in either direction.
Video-related features include video lock capability among several units, memory disable for efficient multi-unit operation, and gen-lock capability to external video.
The VDM-2 is intended to be used in an interactive system mode and provides for the possibility of quote windowing, mixture with live and animated video, and joystick screen control. Programming for the VDM-2 should be done with the enjoyment of the user in mind. [...] »
[author : Ronald T. Borochoff] #Listing #BASIC #Programming
Extract : « The following program is a modification of the 8080 disassembler which originally appeared in the March, 1977 issue of DDJ, Page 25. The program has been adapted to fit a Heath H-8 using Benton Harbor Extended Basic. Capabilities have also been added for listing the numerical opcodes and for an optional continuous disassembly mode.
It is unfortunate that the original contributor wished to remain anonymous, since the program is a superb example of how a well-written program should be devised. The original deserves attention even if you aren’t interested in a disassembler. [...] »
[author : Glenn Story] #Interface #Networks #Protocol
Extract : « In this article I will tell how I went about connecting my home computer, a SOL-20, to the large-scale computer located where I work, which is the Itel Technical Support Center in Palo Alto, California. I will deal primarily with the software I wrote for my SOL, but also touch upon other software and hardware involved, as well as the predefined interfaces with which I worked.
MY HARDWARE
As I said above, I have a SOL-20 computer from Processor Technology. It contains 24K of RAM and uses a Northstar disk for external storage. When I set about this project I acquired a Tec-Com Modem with acoustic coupler. This device, which plugs into the serial port on my SOL, converts the digital signals from the SOL into an audible sound transmitted over a phone line, and translates the incoming sound- signal back to digital form. The former process is called modulation, and the latter demodulation; thus, modulator-demodulator, or modem for short. The interface from the modem to the telephone is done acoustically rather than electronically: a small speaker and microphone on the modem are attached to rubber sleeves into which the telephone handset is placed. This is what is meant by “acoustic coupler.” [...] »
[author : L. H. Reid] #Listing #Assembly #OperatingSystem
Extract : « I herewith enclose two programs which I have found very useful to me when used on my system. [...]
‘SPACE’ is a transient command for use with the Smoke Signal BFD-68 Disk system for 6800 processors. I had found it annoying to have to list a whole disk catalogue just to find the space available left on a drive. This program saves all that and gives it to you more quickly than “QUOLST” by Gary Gaugler, published recently—only because it does not have to sort out all the file types. It is one of those commands whereby one wonders why nobody did it before—perhaps they did and I missed it !! [...]
prtect
I am one of those people who just has to try everything, and when I had unwrapped my ‘Air-Freighted across the Atlantic’ Smoke Signal BFD-68 Disk system and got it up and running, I tried everything—well, almost!
The thing I could not do was to get two of the error codes —no matter how hard I tried! The error codes are for trying to write to a write-protected file (Error 12) and trying to delete a delete protected file (Error 13). Despite a trans-Atlantic telephone call to a very helpful ‘Smoke Signal,’ I still couldn’t find out EXACTLY how to protect my files. In my ‘try everything’ fashion I managed it with the tips SSB had given me and the ‘PRTECT’ program is the result. [...] »