[author : Tom Williams, Assistant Editor] #TradeAndLaws
Extract : « In the June/July issue of Dr. Dobb’s Journal, due to a rising number of complaints we were receiving, we initiated a project which was somewhat facetiously called a “pseudo-contest” for the manufacturer with the longest delivery delay. We asked readers who felt they had been wrongly dealt with to submit documented details for publication. They were to include copies of any cancelled checks, invoices, original order form and any correspondence on the matter in question. In addition, we asked everyone submitting such documentation to sign a statement saying that at the time they placed the order they had no indication there would be more than a one-month delay in delivery and that they had not received an offer of immediate refund of their advance payment when an undue delay became apparent. [...]
The case histories that follow are ones we received that were particularly well documented and which we feel, based on more general information available to us, are indicative of what is going on in the market as a whole. It should further be pointed out that the companies mentioned were not singled out as particularly major offenders; they are the cases which people sent us, and due to the small actual number of cases we received they can only serve as examples. Nonetheless, the cases we recount here are real enough in themselves that useful information can be obtained from them. [...] »
[author : not disclosed (criticism side), Louis E. Frenzel (response side) ] #Computer #Review
Extract : « Editor’s Preface: We have received the folio wing evaluation—criticism—of the H-8 from someone whom we know personally, and whose judgement we generally respect. At the author’s request, we are witholding his name, however we will forward any correspondence that may be directed to him immediately upon receipt. [...]
A CRITICAL LOOK AT THE HEATH H-8
This is probably the worst 8080 based personal computer system to come along in a while. While Heath (a division of Slumberger) is a reputable company that has put out (and continues to put out) many fine products backed up by some of the best assembly, check-out and operational manuals in the business, this one is a dog. It is badly designed from the printed circuit layout to the cabinetry to the operating software.
The first thing that any potential customer should know is that the H-8 is not in any way compatible with the S100 bus. [...]
RESPONSE TO CRITICAL ARTICLE ON THE H8 COMPUTER
The author’s first objection has to do with Heath not adopting the S100 bus. When the development of the H8 began in 1975, the term S100 did not exist. Nor was that bus widely used as it is now. The MITS Altair had only recently been introduced. It was the only microcomputer available. Naturally we looked at that machine and studied the bus structure.
The S100 bus is an old bus design that assumes you are using an 8080 without the system controller (8228/8238). There are many unnecessary signals on the bus. Less than half of the total 100 lines on the bus are useful or needed. In addition, the bus has a variety of noise and timing problems. It is also an expensive bus in that it uses high cost printed circuit board edge connectors. We knew that we could produce a lower cost bus with greater electrical integrity. That is what we set out to do as others have done (Digital Group, etc.). [...] »
[author : Richard B. Emerson]
Extract : « COPY OF A LETTER DIRECTED TO POLYMORPHIC SYSTEMS
Dear Sirs:
I recently purchased a POLY 88 system from Personal Computer Corp. in Frazer, Pa. The system consists of a System 2 with IMS’s 8k RAM and IMSAI’s 4k RAM. The peripherals are a converted JVC receiver, a Superscope C-103, and a Claire-pendar keyboard. At this time the system is running satisfactorily, but it has been a difficult fight to get to this point. Problems can always be expected when attempting to bring any computer up for the first time. As a systems analyst for a large university, it is a fact that is often called to my attention. The problems that I encountered, however, were avoidable for the most part had more consideration been given to the manual shipped with the system. In addition to the errors and confusion in the documentation, there were missing diodes and sockets. [...] »
[author : Neils Laughlin] #Languages #Programming
Extract : « Dear Dr. Dobbs:
I am in the process of writing a compiler/interpreter for a version of Dijkstra's so-called minilanguage he introduced in his book A Discipline of Programming in 1976.
I would like to hear from any hobbyist who is working along similar lines. Eventually, I hope to have my IMSAI 8080 programmed exclusively with this language, eliminating all assembler code, even from the monitor and I/O drivers. The compiler will be written in the language itself and should be ready by January 1978. I should point out that I do not yet have my hardware up and running - - I wish I bought it assembled.
Included is a description of Dijkstra’s minilanguage as I will use it, along with a recoding of “HI-LO”, a game program which appeared in April 1977 issue of Kilobaud. [...] »
[author : Jonathan W. Mills] #Listing #Assembly #Graphics
Extract : « [...] This program provides an easy way to write graphics into a 2K block of RAM addressed by the Cromemco TV Dazzler. This program accomodates the complex Dazzler interpretation of memory so that the user sees it as 128 horizontal lines, each 128 contiguous bits wide, instead of four quadrants with each byte’s bits arranged in a “ZZ” pattern. A detailed explanation of this transform operation is provided in the theory of operation.
GRAFX puts the Dazzler into the 128H by 128V (“resolution X 4”) mode, and black-and-white display. Other modes can be chosen, but consideration must be given to resulting “oddball” behavior, such as losing the cursor offscreen when using only 512 bytes of memory for the display, or failure of the cursor of “move” in the normal (64H by 64V) mode. In this case, the current location will go through several color changes as the cursor steps through the memory nybble and will move to the “next” location only after entering the next “nybble”. [...] »
[author : Arthur Armstron] #Listing #BASIC #Assembly #Graphics
Extract : « Editorial Note: Profuse thanks for the material and since we do not pay for contributions we bestow herewith eternal fame. — TRW
After using my Polymorphic video display board for about six months for drawing graphs I wanted a way that would be easier to use and quicker in execution. The BASIC programs calculating and poking into the VDM memory, while challenging to write, were complex and slow. This article presents the results of my attempt to improve the process. I won’t mention all the things I tried that didn’t work. Perhaps someone more familiar with MITS BASIC than I can offer something better. This patch is for MITS 3.2 8K BASIC. I suspect most basics would be comparable.
The video display is considered to have coordinates from 0 to 127 from left to right and from 0 to 47 from bottom to top. The plot function (PLT) uses the first two variables defined in the program to locate the horizontal and vertical coordinate, respectively. [...] »
[author : Edward M. McCormack] #Storage #Music #Interface #Electronic #Time #Listing #MachineCode
Extract : « It is possible to do a number of interesting things with the basic Elf at an additional hardware cost of less than $5. This article describes programs to read and write programs and data to and from ordinary cassette recorders, to play music, to interface with a Teletype, to measure frequencies and to measure time intervals. The trick is to trade software for hardware by taking advantage of the precise timing control possible in the Elf. These applications require a 2 megahertz crystal.
It will be noted that these programs deviate from normal programming practice because of the need to have the execution time the same no matter which logical path is followed and to assure that both halves of a tone being generated are exactly equal. [...] »
[author : Edward M. McCormack] #Electronic #OperatingSystem
Extract : « There are three significant limitations to the basic Elf microcomputer. They are (1) limited memory (2) lack of an operating system and (3) volatility of memory. This article describes an overall system for overcoming these limitations at a cost of $25 more than the basic Elf itself. It is based on improvements given in Part 3 of the series on the COSMAC Elf which appeared in the March 1977 Popular Electronics. The system uses 1K RAM, a 256 byte EPROM operating system and an ordinary cassette to load and unload RAM. It operates immediately when turned on. The operating system facilitates program execution and manipulation of the data in RAM. [...] »
[author : Charlie Pack] #Listing #BASIC #Office #Finance
Extract : « [...] The purpose of this program is to total and balance any kind of multi-accounting journal that has dollar amounts arranged in columns and rows (lines). The program adds columns vertically and rows horizontally (totals and crossfoots), and then prints various types of reports including a trial balance report and a statement of cash income and expenses. It also functions (with a video display terminal) as a powerful desktop adding machine.
There are several advantages in using a computer instead of an adding machine or calculator to balance a multi-column journal. It’s true, of course, that in either case all of the numbers must be keyed in. But there the simillarity ends. The computer can “remember” every single debit and credit entry! It’s like a calculator with an almost unlimited number of directly addressable memories, any of which can be recalled individually or by column or row instantly. There is no need to compute column totals and then have to re-enter them to get a trial balance (the sum of all the debit and credit column totals should balance, or add up to zero). The computer will do it for you automatically at the touch of a key. Errors are easier to find and correct because numbers don’t have to be re-entered. Just enter only the corrected debit or credit amount and new totals can be computed immediately. Furthermore, the terminal shows a neat, formatted display which is much easier to read than 10 feet of adding machine tape. And, if you have a video display, it’s silent and doesn’t use up paper. So, let’s put that home computer (almost anything that can run BASIC) to work! [...] »
[author : H.T. Gordon] #Listing #Assembly #Programming