kitchen kync Alan Groupe
A pocket reference card should jog your memory, not teach something new.
Shirt-pocket Shaman
A common complaint I have about most computer documentation is that, while the manuals often say too little, the "pocket reference cards" usually say too much. A pocket reference card should not actually teach anything new, but rather just jog your memory of things you have already read in the manual. These cards should contain mostly tables, and rarely, if at all, complete sentences.
A case in point for the need of such a card is the Sinclair ZX81 manual. One of things I often look for is the table of error codes, but 1 have to flip 22 pages from the back of the book to find it. It is not close at hand.
Consequently, I was very happy to learn that Nanos Systems had added the ZX80/ZX81 to the list of machines for which they produce pocket reference cards.
Nanos Systems Corporation is Shirley A. and Paul P. Nanos of Speedway, Indiana, and has produced much needed
reference cards for machines such as the Apple II and TRS-80. When I found that they had done one for the Sinclair, I decided that I bad to get one.
The card size (3-3/4" 8-1/2" folded; 37-1/2" x 8-1/2" unfolded) is a bit more unwieldy than the much smaller "
pdp11 Programming Card" that I am used to, but it is still easy enough to work with. Normally, you would only have a couple of panels open at a time.
The card has 20 panels. The 10 panels on one side are chock-full of all sorts of good information about programming the ZX8O/ZX81/TS1OO0 in Basic. The 10 panels on the reverse side are all concerned with programming in Z80 machine language. (I assume that these panels are the same ones found in other Nanos Systems cards for Z80 based machines.)
Panel 1 is taken up entirely by the 22 graphic symbols in the Sinclair character set. It does not seem to me that so much space needs to be devoted to this since the graphic characters are adequately presented in the code chart on panels 5 and 6.
Panels 2 and 3 list the Basic statements, commands, and functions in a very concise and readable format. One section shows the derivation of additional trigonometric functions using the built-in functions of Sinclair SK Basic. This is a very nice addition to the card, although in all my years I have never really had to know how to calculate an inverse hyperbolic cosecant.
The top section of the next panel lists the special characters and operators in Sinclair Basic. The bottom section, entitled "screen layout," puzzled me at first. Il turns out to be a chart of the memory displacement and PLOT command Y-coordinates for the 24 PRINT lines on the screen. This chart is correct however, only, if you have the 16K (or more) RAM pack since otherwise the screen is stored compressed.
Panels 5 and 6 show the full character set, in decimal, hexadecimal, and the ZX80 and ZX81 graphics. This is a very handy chart despite the layout {see Panel 7 contains "ZX81—selected ROM calls," though I do not know how the 8 routines listed came to be the chosen ones. Panel 8 contains tutorials on using FOR/NEXT and IF-THEN. As I mentioned in the beginning, 1 do not believe that tutorials belong on a reference card, but rather in a manual, where they can be more fully detailed. Needless to say, while it certainly did not hurt to have them, I do not fee! the usefulness of the card would have been diminished if these two panels had been omitted.
The last two panels describe the ZX80 and the ZX81 memory layout and the Basic error codes. Located at the back, these are very easy to get at.
As good as the front side is, the flip side is not. While the front is very helpful in tracking down Sinclair specifics, I cannot recommend the back side as being particularly helpful in writing machine language programs. The back side is basically divided into two large sections. The first lists all of the Z80 instruction combinations and the length of time to execute each. This is useful if you are trying to optimize code or are building a delay loop.
The other section lists all of the instruction combinations in numerical order (by opcode) along with hexadecimal and decimal counterparts. This is useful if you wish to disassemble some of the monitor.
What is missing, however, is some convenient manner of hand assembling from symbolic instructions to a numeric counterpart. A similar list of all instruction combinations in alphabetical order was sorely lacking and would have been very useful.
The layout of the card could have used a bit more thought. For example, the character code chart, which takes up panels 5 and 6. is not placed on facing panels. As a result, you have to open up four panels to use the code chart. This does not matter if you have a large enough table available, but I usually keep the card on my lap.
Still, the Nanos Systems reference card is clear, concise, and, for its shortcomings, is the best handy reference for the ZX80/ZX81 I have seen. If you really like experimenting with your Sinclair, I cannot think of a better way to spend S5.95 It is well worth the price.
