80-Bus News


July–October 1982 · Volume 1 · Issue 3

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Reading ZEAP Files to Disk

Quite a number of Nascom owners must have by now purchased the Gemini CP/M disk system, and no doubt many will want to transfer their ZEAP source files onto disk. The “Disk Basic Constructor” disk has software on it for doing this with tape files produced with the Nas-Sys “W” command, but there appears to be no easy way of doing this with ZEAP source files or Hisoft Pascal source files.

In fact, it is quite simple to read ZEAP tapes via the UART, using the command STAT CON:=BAT: which inputs data from the UART instead of from the keyboard. The problem is that as soon as the above command is executed the keyboard goes dead and you cannot now call up the editor into which the tape is to be read. From now on all commands and input have to go in via the UART. To call up the editor via the UART, you either record the ASCII command “ED filename.xxx” on the beginning of your ZEAP tape (followed by a CR, a big gap for ED to be loaded and I CR), or you have to use a second Nascom and join their UARTs together. Then the above command would be typed on the second Nascom and when ED is running the cassette deck is switched on.

The problem with the first method is that I cannot find an easy way of recording direct ASCII onto a tape, and the second one requires another computer. If it were possible to change the IOBYTE from within ED the problem would be solved.

When your ZEAP file is finally on disk you will want to remove the line numbers; most assemblers doe not have numbered lines in their source files. The ED macro command 0m5d1 will do this by removing the first 5 characters from each line.

My Hisoft assembler accepts ZEAP source files (without line numbers ) without any editing being required at all. Incidentally, it assembles in just 3 minutes a file on which ZEAP would spend some 22 minutes.

The reason for using the rather confusing and cumbersome ED is because it works via the BDOS and can therefore be directed via the IOBYTE to look at the UART. It also has some very useful macro commands.

Finally, does anyone know of a book which explains in detail the internal operation of CP/M?

P. Holy, Worthing.

Space Invader & Keyboard Mods.

I enclose information to upgrade the excellent game of Space Invaders as published in INMC80 issue 2.

I am sure most readers with Nascoms have this on tape and the modifications give a more pleasing effect, all that is required is NAS-GRA. Should readers like to put in their own solutions for the graphics then ignore the column marked ‘Suggested graphic’.

The Gun

Hex locationSuggested graphic
1B72= 8B (left character)
1B77= AA (centre character)
1B7C= 8A (right character)

The Invaders

Hex locationSuggested graphic
18CB=19E7=18AE=1D8B= A6 (top row)
19EA = 18B3 = 1D8D= B4 (next two rows)
19ED = 18BB = 1D8F= BF (bottom two rows)
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