First Steps

Mark Hutchinson, Belfast


Issue 7

Jan/Feb 84

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There was very little time between issue 6 and the copy date for this issue to receive your questions so here are a few points which readers have raised earlier. I hope that you send in many more questions for the next column.

Q. What is the difference between an upgrade and a 48K rampack? An upgrade is just a general increase in memory whereas a rampack is a memory module connected externally to the computer. To increase the memory of a 400 is quite easy providing you take care when soldering two wires. The new memory comes as a small board that you replace the original with on the main board, also called the motherboard.

Q. As I do not have a recorder how long is it safe to leave the computer on for? Overnight? Normally anything electronic is life-tested over extremes of temperature and humidity. Modern components are extremely reliable and give long service, but just how long I cannot say. I would consider the expense of a 410 recorder to be more economical in the long run rather than risk leaving the computer on 24 hours a day.

Q. What is the right hand cartridge slot for on the 800? Atari have not disclosed what they originally designed the right hand slot for. You can use a programming aid called Monkey Wrench in this slot, and in America you can obtain a disassembler/EPROM burner which will copy anything in the left slot. This does however infringe copyright. Note that the new XL range has only one cartridge slot.

Q. Is it possible to connect headphones to the computer? It is far easier to connect headphones to the TV set and in fact many modern sets are wired for this. If you wish to explore the workings of the machine then get a copy of the Technical Reference Notes which gives circuit diagrams.

Q. How do you work out a number to put in a USR statement?
USR is one of the most powerful commands available to you in BASIC. It is a machine language call that comes in many forms and usually it is better if you know some assembly codes to use it fully. One form is X=USR(SL) where X is a variable or function worked out from the commands placed into memory at location SL. Another is X=USR(S1,S2,N) where S1 is the data you shift from string location 1 to string location 2 and N is the number of bytes moved. This is useful to perform high speed changing of PMG or character redefinition. You will normally see USR used with READ . . DATA and numbers being POKEd into page 6 (1536-1791). These numbers are the decimal equivalents of the assembly codes or memory locations. This is worth a PAGE 6 tutorial and I am sure that someone out there is willing to write such an article to help us out? As a little example of USR, try X=USR(61530) and SYSTEM RESET.

Q. Is it possible to control an external relay with the I/O socket? If you have the technical expertise then, yes it is possible. The serial I/0 port on the right hand side of the machine switches the 410 recorder on and off, provides a +ve 4V data and even allows a +ve outlet against its own ground for peripherals. Here is a diagram of the SIO pins but note that a lot 

more may be available using the controller ports as they can be directly read from potentiometers. Once again I recommend the Technical Reference Notes as this is a large area to cover. A good memory map will help or even an article in PAGE 6? (There will be an article covering this in Issue 8 - Ed.)

Some of the questions this month have been a bit technical but do not let that put you off sending in any questions however simple. Don't forget to let me know if you do not want your name published.

Write to Mark at BAUG Software, P.O. Box 123, Belfast, N. Ireland BT10 0DB.