ZX81—The Family Increases
A number of people have asked us whether we are going to include the ZX81 in our coverage. As our changed cover shows, the answer is a definite YES.
With the multiplication of the ZX80 family and the availability of new ROMs and RAMs, our readers want to know what the machine requirements of our programs are. If you are planning to send us an article or program that you have developed, be sure to state the minimum machine requirements for your program on a separate line below the title. When we are referring to the general family or discussing the family in areas where the ROMs and RAMs are not important, we will say simply the “ZX80,” but where the ROM and RAM are important we want to include that information.
PERCEPTIONS
In this issue we are introducing the column PERCEPTIONS by David Ornstein (p.6). David has already contributed to SYNC through his work on the schematic of the ZX80 in issue 1, “Video Modifications for the ZX80” in issue 2, and “The ZX80 Keyboard” in issue 3.
Though he is Technical Services Manager for Sinclair Research Limited (U.S.), we must hasten to point out that the views expressed in his column will be strictly his own and in no way will represent Sinclair Research.
SYNCSUM
We are especially pleased with the first contribution of PERCEPTIONS to SYNC readers and authors in the concept and programs for the SYNCSUM. This is a method of checking whether you have entered the program correctly. If you are submitting an article, we ask you to include the SYNCSUM at the end of any program listing.
Spaces in PRINT Statements
Since we do not have a symbol on the ZX80 that marks clearly the empty spaces, sometimes problems arise in entering programs and getting them to work because the correct number of spaces in the PRINT statements is not always clear. When we receive a program done on a typewriter or a printer, we can usually figure out the number by counting the letters in the line above or below since each letter takes up the same amount of space. However, this is not always accurate because typographical errors can occur even in leaving spaces. Another problem comes up when we typeset programs. On the type setting machine letters vary in the amount of space they take up in the line and the spaces also vary in order to make the right hand margins even. So counting does not work. We have tried to handle this problem up to this point by indicating the number of spaces in a side note. Beginning with our next issue, we will be using a symbol to indicate spaces where these affect the running of the program.
If you are submitting a manuscript, we are asking you to indicate all spaces in the PRINT statements except the obvious ones between words by using the symbol #. We have chosen this because it is found on almost all typewriters, and it is not used on the ZX80 family of computers. We will use a different symbol in SYNC articles, but, even if we slip up, # will not cause any programming errors since it cannot be entered.
If in running a program you are sure that you have entered it correctly but it still does not work, check the number of spaces in any PRINT statements. You might experiment by changing these.
MicroAce II????
Contrary to some reports, MicroAce is not planning at the present time to offer a MicroAce II. When the present stock of kits is exhausted, the MicroAce computer will no longer be available from MicroAce. The company goal will be to offer equipment to upgrade the machines already sold. An 8K ROM and a flicker free video board (which requires 8K ROM) will be available by the time you receive this issue of SYNC. The RAM capacity will be expandable by two options: a 4K RAM and a 16K RAM. These are planned for the fall.
SYNC Subscribers Pass the 6000 Mark
At the end of June our subscription list totaled 6135 subscribers with 1532 outside the U.S. California leads the list with 13% of the total, followed by New York with 7%, and then by Illinois, Texas, and Massachusetts with about 4% each. Outside the U.S. the United Kingdom leads the list.
A P.S. from Alger Salt
Readers of Alger Salt’s “A Parallel Interface for the ZX80/MicroAce” should note the following P.S. which arrived after our layout was completed:
After reading the article “The ZX80 Keyboard” in the May/June issue of SYNC I learned that the keyboard is an input device that is addressed by any even address. This accounts for the difficulty I encountered when trying to read from port A on the PIO. The problem can be avoided by using address line A2 instead of A0 to select the A or B port. That is, connect the A/B SEL line on the PIO to a different address line than A0. Then use only odd addresses when addressing the PIO, i.e., addresses with A0 = 1.